# Electronic Wood Stove Control



## ControlFreak (Jan 25, 2008)

To all,

We are a small company in MA that has developed an intelligent electronic wood stove control system and would like to hear your feedback.  Please, this is not spam, but intended to probe a subject that I rarely hear about -- combustion control in wood stoves.

To kick off the discussion, I'll ask several questions:

1.  Why hasn't this existed until now?  We have some ideas, but want to see what you guys think.  We already know about the use of bimetalic springs to do this, and using a timer to close off a start-up draft control, but what about an electronic system that is intelligent and offers flexibility and adaptability?

2.  Have you ever asked a stove store about something like this?

3.  If you were purchasing a new stove, would you purchase this if it was an option?

4.  If you were to choose between two different, but comparable models, would this feature cause you to choose the one with the controls?

5.  Do you ever overheat your stove by forgetting to close the draft control?  If so, how often.

6.  Do you know of anyone who has had a fire because of an unattended wood stove?

What other questions are there??

OH, our marketing people won't be happy with me if I don't mention the survey on our website.  There will be a drawing for an Ipod for those to complete it.  Relax, it's a very short and easy survey.

Thanks a lot,

Dan McFarland
www.inveninc.com


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## karl (Jan 25, 2008)

That's a pretty insert you have on your home page 

How about a module that turns a fan on to blow air into the primary air intake on the stove to help us get rid of the coals?


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## babalu87 (Jan 25, 2008)

I want mine on a remote control. Sometimes I damper it down to quickly and would like to open the air inlet from the comfort of my couch.


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## Mmaul (Jan 25, 2008)

I like to adjust mine, but, atleast I know if the wife is at home by herself or if my father-inlaw comes over than its operating like its supposed too.


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## ozarkjeep (Jan 25, 2008)

Seems like a great idea Dan.

Im curious , How would one install the actuator and thermo probes in an existing stove?

Or are you primarily looking at integrating it in at the stove factory?

and how much would this unit cost?


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## begreen (Jan 25, 2008)

To kick off the discussion, I'll ask several questions:

1.  Why hasn't this existed until now?  We have some ideas, but want to see what you guys think.  We already know about the use of bimetalic springs to do this, and using a timer to close off a start-up draft control, but what about an electronic system that is intelligent and offers flexibility and adaptability?

*This is a big question. In general, with wood stoves, simplicity is a virtue. Given the wide range of variables in stoves and flues, I think this might have a significant number of stoves that it would work well on. But also, there would be a significant number is might work poorly on, due to drafting variables or problems inherent with the flue system that this device can't cure. There is also the expense and setup time. How many people would be qualified to install this? Would they need to come back and adjust regularly as seasonal changes occur that dramatically affect draft? And then there is the fact that many wood stoves are installed because they provide heat during power outages. Is the system very easy to manually overide? Then there is testing and lab certification. The safety risks if there was a malfunction could be large. *

2.  Have you ever asked a stove store about something like this?

*No, but I have thought about it. *

3.  If you were purchasing a new stove, would you purchase this if it was an option?
*
Unlikely, it doesn't seem that adaptable to Jotuls with the front draft control without hanging a lot on the front ash lip. Aesthetics are important. Also seems a bit pointless on VC stoves with the bi-metallic. How would it function on stoves with a bypass damper?*

4.  If you were to choose between two different, but comparable models, would this feature cause you to choose the one with the controls?
*Depends on the pricing. I probably wouldn't want to be first on the block unless I was home full time and able to develop a trust for the device.*

5.  Do you ever overheat your stove by forgetting to close the draft control?  If so, how often.

*We've never overfired this stove, but is has happened with our old F602. We very rarely, leave the damper open without listening for the stove. But it certainly can happen.*

6.  Do you know of anyone who has had a fire because of an unattended wood stove?
*No.*

What other questions are there??
*Price? What stoves has it been tested on? Have you considered more display options and a bigger readout?
*


That's my 2 pennies worth. Hope it helps.


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## jbrown56 (Jan 25, 2008)

Hi, I am a guy with a pretty severe walkiing disability and spend most of my time on the kitchen level and the stove is on the lower level. When I first load the stove, it must be adjusted a few times before closing for the long burn. I always wondered if there was a device which I could control from the kitchen level as I can see the stove from there. It would save me many trips up and down the stairs. It would have to be something that could be controled myself because of the variables associated with wood burning. BeGreen brings up a ton of good points as usual.

Jim


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## webbie (Jan 25, 2008)

ControlFreak said:
			
		

> To all,
> 
> 
> 1.  Why hasn't this existed until now?
> OH, our marketing people won't be happy with me if I don't mention the survey on our website.  There will be a drawing for an Ipod for those to complete it.  Relax, it's a very short and easy survey.



wait, you have marketing people and are giving away an ipod? Heck we at Hearth.com don't even have marketing people and can't afford to give away an ipod! So if you are small...we must be tiny!
 :cheese: 

I'm sure you are familiar with Condars original retrofit bimetal unit, which was a circular device that fit over the draft control (most were spin type at the time)..... this system actually worked pretty well in some tests, and then worked even better than well when it was incorporated into an entire stove design (with a catalytic converter).

It might be that the market for this ends up being more OEM than retrofit. If and when manufacturers actually start caring about real world efficiency, safety and control....it might provide a talking and selling point. If nothing else, you might want to get in touch with Corie here in the board (he's an R&D;guy)...and perhaps he can try it on some of his stoves at home (he's building an epa lab in his garage).

For the average user, it is probably going to take some "proof" of vast advantages. If you listen to my newest podcast with John Gulland, you will see that he favors manual controls over bimetallics....and he is considered an expert. Heck, John might be willing to try one of your thingys on his stove - that would get your a REAL opinion.

Good luck and welcome to hearth.com, home of the "no-ipod" giveaways.


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## sixminus1 (Jan 25, 2008)

As was previously mentioned, a remote control would be nice.  In addition I would also yearn for wired/wireless integration with a PC.  It would be nice to be able to monitor or change the activity of the stove while I'm at work, via some sort of web interface.  I would also be interested in keeping statistics about how the stove is operating, so I can compare numbers day-to-day, month-to-month, or year-to-year.

There has been a lot of talk about integration between different appliances in a "modern" home -- why not include the woodstove?

And again, cost is a big factor...


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## Hogwildz (Jan 25, 2008)

I have to say this, they have great taste in inserts on the start page of that website  Nothing but the best!


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## billb3 (Jan 25, 2008)

will it work better than the cel phone that doesn't work quite right all the time ?
will it work better than the iPod that every now and then loses its playlist ?
will it work better than the computer in the car that flashes orange lightts on the dash everywhere but at the dealer's ?
will it work better than the motion controller that has to get temperature adjusted 4 times a year in NE ?
will it work as advertised ?


A bit of cynicism, it's Friday.
A week full of electronic 'conveniences' that don't quite work like they're supposed to all the time.
Going home to find the wedge and maul. The splitter probably won't start, either.


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## WarmGuy (Jan 26, 2008)

Dan,

Although your product is a good idea, and I've wondered whether something like that exists, Bill B3 has expressed the same thing I was about to post.  When I'm tired of calling tech support lines, or dealing with electronic things which have some design flaw or glitch, it's nice to sit down in front of a good old wood stove and read a book.  

One day, when I found myself on hold waiting for tech support for my *electric toothbrush* I decided that I was going to try to decrease the number of things I owned that might involve tech support calls.

Wood stove users are more likely to have this attitude than others, so you may have some resistance in this regard.

Also, lots of stove owners like to futz with the controls.

Finally, here's a suggestion: Your marketing seems to stress the ease of use:

" the user is free to go about their life without having to be thinking about constantly making adjustments to keep a wood fire burning efficiently."

That may not be the right tack, since a furnace is a lot easier to use (just set the thermostat).  Perhaps you should stress the ability to get the most out of the firewood, and perhaps have the device pay for itself in wood savings.

Hope that helps.


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## webbie (Jan 26, 2008)

adding to warm guy, one important point would also be safety. We can see users here constantly worried about their stove getting too hot.....that is a bigger motivation than not having to futz with the control.

And here is where I have to be a tough guy - Dan, I am an inventor myself, and have 2 patents. I teach classes on invention and bringing products to market. Without being too negative, it is tough (near impossible) to bring a product like yours to the marketplace and make money. I am not saying that to discourage you, but just to make certain you understand the odds (which you probably already do). As inventors we tend to think everyone has the foresight to recognize the brilliance of our products. But the market often does not - in other words, a better mousetrap does not win the prize. A Pet Rock that sells big wins the prize. 

In the case of inventions, there are generally two ways one can find out the value. The first is to spend an almost unlimited amount of time and money and beat their head against the wall until they are either broke, or start selling a few. The other is to find out what the MARKET thinks the products is really worth by finding a manufacturer or other company to buy or license your product. If no one want to do this, it shows that the market may not be ready for your invention.

Of course, there is the third options...which does happen. Some inventors actually succeed after beating their head against the wall. But one should go into a plan with that in mind and know the consequences.

I speak as someone who has a rock solid patent on some very salable hearth products, but is likely to take a bath because I do not want to take five years and spend more good money to make the market understand why they need it.

Well, heck, my marketing people would yell at me (that means me yelling at myself) if I did not promote the sale and licensing of my great inventions here also:
http://www.extendaflue.com/sale/


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## steam man (Jan 26, 2008)

I hate to say I think a few posters here are missing the point by requesting a "remote means" of manual control rather than a fully automatic "set it and forget" type of device. I have (and still do) operated and installed combustion control dual fuel systems for large marine steam boilers. They always have fully automatic and manual control. The device mentioned seems like it should work fine at least as far as a safety device and making more efficient use of burning wood. I realize the cost will be a big factor. I just wonder if going a step further with possibly stack O2 measurement (for  excess air) would be something to consider for really efficient operation. I understand some of the newer wood boilers will be having this feature. The O2 probes I am aware of are pricey and maintenance hogs though. My guess is that we would find that each stove would work with an precise load of wood for best operation. Disclaimer-wood burning is not my specialty. I do think most stove nuts here would like some kind of remote monitor option possibly to alert for problems and time to fill the stove.


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## Buck1200 (Jan 26, 2008)

Dan, you and I emailed a few weeks back.

As someone who piles 4-5 cord a year through a Heritage that's a little too small for this drafty old house (the stove needs to be hot all the time), I would certainly be in favor of automated control for the following reasons:

Efficiency: I find that the *fastest* way to get a good secondary burn going is to rip it wide open (even with the door open) to 700 degrees on the flue gas thermometer and then damp down entirely.  At issue is that I will typically see flue gas temps of 800+ for the first hour.  Lot's of wasted heat going up my nice expensive insulated stainless chimney.  

If I damp down progressively and slowly (i.e. babysit the thing for half an hour) I can get good damped down operation which peaks at 500 degrees and rides the sweet spot of 4-500 for the bulk of the burn- nice and efficient.  An electronic controller would free me of this babysitting which, quite frankly, is getting old, and is the primary reason I spend most of my hearth.com time sitting in the Boiler room reading about Tarm and EKO.

Time:  I pretty much covered that above... I don't have time to babysit.  5 firings a day x 1/2 per = more time than I have to spend tending the stove.

Operator expertise: A-hem... my wife is not so diligent with the stove watching.  

Cost is certainly an issue however.  I'm still on the fence.


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## babalu87 (Jan 26, 2008)

This could be fairly simple with a hi-torque motor and remote control. At least with my stove there is one control and it is on a pivot point, I have already dreamt it up just havent put it on paper.


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## sixminus1 (Jan 26, 2008)

I can't say that I'm completely sold on this idea/product, and I'll admit that I'm a bit biased in favor of tech, but, there seems to be an aversion to technology floating around here.  It's surprising to me that folks who are so willing to tinker around with their fireplaces and stoves seem to be so afraid and frustrated by new gadgets and devices.  Yes, you'll have to tinker with it to make it work properly, and it may never deliver 100% of what it promises.  Does anything?

Remember -- at one time, *the ability to start a fire* was new technology.


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## cmonSTART (Jan 26, 2008)

It sounds like a gadget I could have a use for as long as it had some sort of manual mode.  

Any device I attach to my wood stove had better deliver 100% of the time.  It's the 1% it doesn't that could cause damage or even burn your house down.


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## kolbyTheDog (Jan 26, 2008)

I would really like some type of temp sensor that I could put on the stove or in it that was connected to a big LCD display (4"+) so I could monitor the various temps of the stove. Maybe it could have 3 or 4 temp probes connected to it and it the display could cycle through the different readings. It would also be great to set min. temps so it would beep to alert me as to when the temp has gotten too low. That would end the fighting between my wife and I as to when is the right time to load the stove, close the damper, turn the blower on, go to bed! We argue about when to do these things more than anything. It would also need to be back lit and run on AC and DC. If it had USB or WIFI built it I could connect it to my computer to log the data just for fun.


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## sixminus1 (Jan 26, 2008)

cmonSTART said:
			
		

> It sounds like a gadget I could have a use for as long as it had some sort of manual mode.
> 
> Any device I attach to my wood stove had better deliver 100% of the time.  It's the 1% it doesn't that could cause damage or even burn your house down.



I completely agree.  Seems like the type of thing that would have to be tested and certified as strictly as things like medical hardware.  Come to think of it, as Craig mentioned, it sounds like a better fit for OEM, rather than some type of retro-fit that leaves the idiot factor wide open for disaster (never underestimate the ingenuity of complete idiots).

The thought of "automating" a wood fire is a little scary, but as you said -- if it's well-tested, and can be completely shut down to allow full manual control when necessary, I think it would be a very cool thing to have.

A stove with this feature would require the same diligence as bringing fire into your home in the first place -- try it out, keep an eye on it, and make absolutely sure that it does what you expect.  Don't leave it alone until you trust it, and even then, don't completely trust it.  It would also require the same type of learning curve that everyone on this forum had with computers (and stoves) -- how to use it properly.  It's a tool, it's a human invention (thus, it's imperfect), it's potentially dangerous, and everyone's mileage will vary.  Hey, that's life.

So, to avoid rambling more,  *ControlFreak:* good idea, now tell us more.


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## Todd (Jan 26, 2008)

Is this just for steel/cast non cat stoves? Can it work with a cat stove that has a bypass? 

What about soapstone? Soapstone is slower to react in up and down heat cycles, how would that affect the performance?


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## Corie (Jan 26, 2008)

Dan,

We spoke last year at the HPBA show, if you remember?  Will you be attending this year?


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## velvetfoot (Jan 26, 2008)

I have an aftermarket switch on my insert that turns the fan off or on depending on temperature, but it would be nice if the blower speed was automatically changed as the air outlet temp got lower.  So, the fan would go lower and kick out roughly the same temp air.  You wouldn't need actuators to move rods, just control the blower speed.


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## precaud (Jan 26, 2008)

ControlFreak said:
			
		

> We are a small company in MA that has developed an intelligent electronic wood stove control system and would like to hear your feedback.  Please, this is not spam, but intended to probe a subject that I rarely hear about -- combustion control in wood stoves.



I own and use a stove that has remote control of the primary combustion air, the Nestor Martin X33. While I haven't written a thorough review of it yet, do a search on this site for X33 and you'll see my previous posts about it. The remote control setup is licensed from a US company - Ambient Technologies in Paris, KY. Their website is:  http://www.ambienttechnologies.com/

The system has basically four modes of functioning:
1. Manual remote control - the user controls the primary air intake via the remote buttons. I use it and like it. I can tweak the burn rate without going to the stove.
2. Programmed turnon time - the user programs a time at which the system opens the primary air fully. Without an ignition system, this mode is pretty useless. Even if it did, I wouldn't use it... sounds dangerous to me.
3. Programmed burn duration - the system closes the primary air intake after a set period of time. I use it occasionally, when I load the stove and leave the house. Useful.
4. Remote thermostatic control - the remote attempts to maintain a set room temperature by varying the air intake. I find this quite useless, given the relatively small batches of fuel the stove is capable of handling.

Having used this system for a couple months, I can say, I do like it for modes 1 and 3 above. But, while I find the idea of using technology to optimize the combustion process intriguing, I wouldn't own anything that attempts to control the stove further than what this system does. Wood stoves are batched-fired devices, and my interaction with the stove plays a significant part in why I prefer this form of heating.


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## ControlFreak (Jan 27, 2008)

Corie,

We will be at HPBA in Atlanta.  We're not doing a booth so we're more free to go and seek out the people we want to contact.  There was too much idle time waiting around for people to wander by last year.  We will be bringing portable demonstration hardware so people can get a sense for what's going on with this.

Dan


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## RedRanger (Jan 27, 2008)

Gadgets are not meant for stoves or inserts.  They malfunction, there goes your house.!!

Right now I`m thinking of greenhouses, where the vents open or close depending on the heat and humidity,Sometimes They Fail!!

Never,never would I trust one of these things.  I want to be able to leave my home knowing the manual controls I use have set the insert to minimum burn,will stay that way.  When I go to bed at night, same thing.  Don`t want to be tossing and turning wondering if this new gadget is going to malfunction and leave everything "wide open"?

Maybe you can sell this to the inexperienced wood burners, but not to the rest of that are still (partially sane) :coolhmm: 

Some of you experienced wood burners may disagree?  But remember, I said that those of us that are at least Partially Sane, would never,ever even give this product a -second nod...


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## BrotherBart (Jan 27, 2008)

Well, that did it. I have just got to have one now. ;-)


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## ControlFreak (Jan 27, 2008)

Hi Sonnyinbc,
Thank you so much for your candid feedback.  Every bit of feedback we get is valuable, even feedback that's not favorable.  Reliability will be a key area of focus.  
Dan


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## ControlFreak (Jan 27, 2008)

To address a lot of the questions and comments posted here, here’s some info:

I began heating with wood in 1996 with a Napoleon 1401.  After about 6 years, I became very tired of constantly having to monitor the draft setting in order to have a nice clean fire without overheating the stove.  It bugs me if the fire is smoking up the glass in the door, and worse, when I forget to check it and come back too late and the fire is so hot that the draft control can't even slow it down.

A pellet stove is not an option.  It's just not a real fire, and I don't want to be tied to a pellet supplier.  So this is the closest thing to the convenience of a pellet stove, but still having the cost advantage and beauty of a real wood fire.   
In 2004 the development began for SmartStove.  Between then and now, we have gone through many revisions of the product to get to where we have a reliable and reasonably fault-tolerant control system today.  For the past three winters, I have run my Napoleon stove with various prototypes, experimenting and learning what works, and what doesn’t.  As the system runs, it logs the operation so data can be downloaded and performance can be examined at the end of the fire.  I have logged many fires and tuned the controls so it now runs the stove better than I ever did. 

The product was developed with these considerations and requirements:
1.    Safety.  #1.  It MUST be failsafe when AC power drops.  Must never fail with draft wide open.  
2.    Reliability.  It must never fail, but if something does go wrong, like an open door, it should warn the user.
3.    Functionality.  It must work perfectly --- always.  Otherwise it’s useless.
4.    Cost.  It must be affordable, or nobody will buy it.
5.    Flexibility.  It must be configurable for many stove applications.
6.    Adaptability.  It must be able to self-adapt to various draft configurations.

Dan


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## ControlFreak (Jan 27, 2008)

To respond directly to some of the comments:

"I want mine on a remote control. Sometimes I damper it down to quickly and would like to open the air inlet from the comfort of my couch."  That's what this fixes.  It will be dampered down just right.

"Im curious , How would one install the actuator and thermo probes in an existing stove?"  _We are targeting OEM installations for new stoves._
"Or are you primarily looking at integrating it in at the stove factory?"  _Yes._
"and how much would this unit cost?"  This is one area of study.  It needs to as inexpensive as we can make it, but also reliable.

"I am a guy with a pretty severe walkiing disability and spend most of my time on the kitchen level and the stove is on the lower level."  This is perfect for you.

"There has been a lot of talk about integration between different appliances in a “modern” home—why not include the woodstove?"  Maybe some day.  

"I like to adjust mine, but, atleast I know if the wife is at home by herself or if my father-inlaw comes over than its operating like its supposed too."  Initially, there was a auto "override" for the draft control to enable manual control.  It was eliminated since it was never needed, and there was concern that it would be accidently put into manual mode and overheat the stove.   

"How would it function on stoves with a bypass damper?"  SmartStove has the capability to drive two actuators to accomodate stoves like the Quads that have two controls.  

"And again, cost is a big factor…"  It sure is.  I think that this has been an inhibiting factor.  

"Also, lots of stove owners like to futz with the controls."  We will be sure to install special "futz" features.  Acutally, there is a configuration menu where tinkerers can tweak settings.  We'll make sure we put in some special settings just for the futzers.

"Yes, you’ll have to tinker with it to make it work properly, and it may never deliver 100% of what it promises."   Yes that's what normally happens.  Frankly, this by far exceeded my expectations when it was first working.  I'm pretty spoiled by it now.  

"If it had USB..."  We have considered this.  It very well might be there by the time we get to mass production.  I used to download operating data that's logged throughout the fire while checking things out.  

"Well, that did it. I have just got to have one now."  Eventually you will.


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## begreen (Jan 28, 2008)

> “How would it function on stoves with a bypass damper?” SmartStove has the capability to drive two actuators to accommodate stoves like the Quads that have two controls.



I'm sure you looked at this but I was referring to stoves like the Quadrafire Isle Royale, downdraft stoves like the Lopi Leyden, VC non-cats and the VC cat stoves. These are fairly stout bypass controls, not just an air damper. I'm having a hard time imagining how one would put a servo on this. It would require a fair amount of leverage and I would think that the stove is too hot there to attach a motor to.


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## tkirk22 (Jan 28, 2008)

ControlFreak said:
			
		

> To address a lot of the questions and comments posted here, here’s some info:
> 
> I began heating with wood in 1996 with a Napoleon 1401.  After about 6 years, I became very tired of constantly having to monitor the draft setting in order to have a nice clean fire without overheating the stove.  It bugs me if the fire is smoking up the glass in the door, and worse, when I forget to check it and come back too late and the fire is so hot that the draft control can't even slow it down.
> 
> ...



Enough marketing...here are some of  my questions:

Will it fail safely if I was to cut any one sensor or any combination of sensors? 
How about if those sensors are shorted or they receive some external low voltage?
What happens if any of the 3 wires to the air inlet servo fail? 
Will it fail safely if a power surge takes out the micro controller but not the servo circuit?

Please don't get me wrong. I do like the idea. However I also like the idea of children having computers BUT only as long as the computer is not considered the child's babysitter. 

I would also like to put my vote in for you to send a test unit to Corie.


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## ControlFreak (Jan 28, 2008)

BeGreen said:
			
		

> > “How would it function on stoves with a bypass damper?” SmartStove has the capability to drive two actuators to accommodate stoves like the Quads that have two controls.
> 
> 
> 
> I'm sure you looked at this but I was referring to stoves like the Quadrafire Isle Royale, downdraft stoves like the Lopi Leyden, VC non-cats and the VC cat stoves. These are fairly stout bypass controls, not just an air damper. I'm having a hard time imagining how one would put a servo on this. It would require a fair amount of leverage and I would think that the stove is too hot there to attach a motor to.



Controls that require a great deal of power will be a problem that has to be fixed.  You're right.  A servo isn't going to drive these.


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## ControlFreak (Jan 28, 2008)

Kirk22 said:
			
		

> Enough marketing...here are some of  my questions:
> 
> Will it fail safely if I was to cut any one sensor or any combination of sensors?
> How about if those sensors are shorted or they receive some external low voltage?
> ...



Wow, good questions.  Now you're talking about doing Failure Mode and Effect Analysis.  That's not done yet.  We are fail-safe for the most common failure: AC power.  We do have feedback from the draft control so if something hangs up the draft and it doesn't move, the controller can see that it's stuck.


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## TruePatriot (Jan 28, 2008)

Dan,

Crap!

I just lost a 6,000 character post because I bumped into the "character limit Gremlin."  You know, where you type ONE CHARACTER TOO MANY AND THE WHOLE POST DISAPPEARS!  Arrgghhh!! (It may happen when hitting "Backspace" while at the char. limit--not sure).

In short, I refused to buy any steel, NC stove that doesn't offer thermostatic control of the PRIMARY (and possibly secondary) air supply, other than the Englander 30-NC.  I've studed the steel-plate, non-cat stove market extensively, for too many years, *and the Englander 30-NC is meeting or exceeding all performance measures of the $2,200-3,000+ stove market, at 1/3 to 1/6 the price *(if you get one at 50% off at Lowes, as I just did), against even such formiddable models as the Quad 5700.  

IOW, if I can't have thermo-control of the PRIMARY intake air, for $3,000.+, then why would I spend such money, when the Englander 30-NC meets or exceeds the perfomance of such $3,000/+ stoves, at 1/3 the price? (Or 1/6, if purchased at a 50% discount.).

Thermostatic control is the single biggest feature I seek, after materials choice.

In 2007, I contacted every major steel stove mfr. and asked if they were going to offer thermo control.  Quad mumbled "maybe, since we have our ACC system on the market," but the only serious response I got was from Mike at Englander, saying he would forward my suggestion to "the slide-rule types" (my term, not his).  I felt the other mfrs. were just blowing me off--though I felt Quad _might _have been serious, but I doubt it.  I do believe Mike has passed my concerns up the channel, and we shall see if they respond as I hope they will.  If they do, my second stove will be an Englander as well!

I know PE offers thermo control of the SECONDARY air intake, but feel that is too little to accomplish what I, and now YOU, would like to see, i.e., *full thermo-control, where one could select a rate of burn, load the stove, and forget it, knowing it's metering the air necessary for complete, efficient combustion at the output level selected by the operator*.

I know Blaze King offers thermo control, but don't want a cat stove.  I also know some cast iron stoves offer thermo control (Quad's Island Royale, possibly?) but again, I don't want any cat, or cast, stoves.  (No offense to such owners--it's just that I'm l-a-z-y, and don't like replacing cats or furnace cement.  Welded, plate steel stoves make me feel more confident about their integrity than stoves bolted together with furnace cement, but that is my personal preference.  I only mention it here because I want Dan to offer his electronic system to OEM's of _plate steel, welded stoves, _so I can buy one! LOL)

But to recap:  I put off spending $3,000+ on a stove that lacks even the bimetallic intake air control that even some of the smoke dragons of the '70's had.  

If the Englander hadn't been available at 1/3 the price of the Quad 5700, I would have bought NO stove.  So when the Englander 30-NC became availbable for 50% off, or ONE-SIXTH the price of the Quad 5700, but with comparable performance and superior emissions, I bit.  *But I'm determined to wait to spend $3,000. for a "pretty" stove until thermostatic control of the primary intake air is available.*  And, when that is offered, I will buy the new stove and move the 30-NC to my cottage.

Re: the concerns I share with others about a failure leading to a runaway stove, please address this:  *I feel the electronic servo should pull against an extension spring that is contantly trying to close the draft,* similar to how, on a garden tractor engine, the operator opens the throttle against a governor that is contantly trying to close the throttle.  I see this as a common-sense approach to avoiding a failure that results in a runaway.

*I would be into the electronic control's additional features of "logging," remote control and particularly, OVER-FIRE ALERTS and low-fuel alerts, IF I FELT THE FAIL SAFE MODE WOULD RESULT IN A CLOSED DRAFT, and if the stove could be run MANUALLY in case of extended blackouts.*

Sorry I can't write more, *and sorry for the mistakes and poor writing*--as I say, I was one character away from a well-groomed post, answering all of your Q's, when *POOF!* it was gone.  I forgot to write it in Word _first _and post it here, and having been burned like this too many times in the past (sorry, Craig, but it happens to me, too often--I know, I'm a "wordy ****  :lol: ) I'm just too frustrated to rewrite the whole thing.

I seriously hope you pull this off, Dan.  *If for no other reason that it should spur the OEM's to get off their asses and offer the same thing, so we can have the same convenience enjoyed by pellet stove owners, for cryin' out loud!*  It's about FORTY YEARS OVERDUE, since it was offered in the '70's, right?

I would also be interested in a retrofit kit for the Englander NC-30, Quad 5700, etc..., IF you could offer strong assurances that Homeowners carriers and code enforcements' concerns could be met, especially without risking denial of coverage should the woodstove (for any reason, not necessarily involving your system) be cited as the cause to a house fire (knock on wood three times.)  And I have to tell you that, as an attorney, I think that will be an uphill battle, in terms of a retrofit that won't make the carriers underwriters _jump right out of their trees _in an effort to say "NO" to covering such a mod. Perhaps if a licensed professional HVAC guy/gal did the modification, that would help, but I don't know.  I didn't practice in the area of products liability, however, so value my .02 accordingly, on this last point.

I truly wish you the best of luck in pulling this off!

And yes, to sharp the sharp-witted like BB, I realize this post is as long as the one I lost--it's just more rambling and disorganized.  ;-P 

Thanks again.


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## ControlFreak (Jan 28, 2008)

TruePatriot,
Your insight is priceless!  

"I seriously hope you pull this off, Dan."  

I will pull this off.  It's just a matter of time. 

"I would be into the electronic control’s additional features of “logging,”

Take a look at the attachment.  This data was collected two years ago.  This is a plot of a typical fire.  One thing that has always surprised me is how the temp measurement always drops off significantly after about 2-3 hours into the burn.  For a long time I questioned the measurement.  You'd never expect to see this from watching the fire.  Anyway, I download these frequently to see how the night's burn went and whether the code is doing what I expect.

Dan


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## begreen (Jan 28, 2008)

Dan, what stove was this tested on? Is the draft spike at the end due to opening up the air control fully to burn off coals? I'm surprised to see no corresponding rise in stove top temp.


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## begreen (Jan 28, 2008)

TruePatriot said:
			
		

> Dan,
> 
> Thermostatic control is the single biggest feature I seek, after materials choice.
> 
> ...



My understanding is that PE's EBT controls primary and secondary air. This is only on the Summit/T6 models. VC stoves have thermostatic damper on the secondary. To my knowledge, the Isle Royale does not. 

I've only had a thermostatically dampered stove once, the original VC Resolute, but I agree, it was really nice to have and worked well. I too hope Dan succeeds with this endeavor and in prodding other manufacturer's to incorporate thermostatic control. To be fair though, John Gulland does not. He would be a good one to setup with a test unit.


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## Woodrat (Jan 28, 2008)

BeGreen said:
			
		

> I've only had a thermostatically dampered stove once, the original VC Resolute, but I agree, it was really nice to have and worked well. I too hope Dan succeeds with this endeavor and in prodding other manufacturer's to incorporate thermostatic control. To be fair though, John Gulland does not.



Question-- Do you know WHY not????

    Woodrat


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## begreen (Jan 28, 2008)

Good question. I don't remember him going into much detail during the interview with Craig. Seems like a good topic for him to expand on in the next one.


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## TruePatriot (Jan 28, 2008)

Dan,

Thank you for this:


> TruePatriot,
> Your insight is priceless!



I don't hear that nearly enough--lol.  Can you tell my g.f.?

And seriously, there is a pretty serious discussion of thermostatic control shaping up in a (unfortunately, highjacked?) thread over here, regarding PE's increasinly-mysterious (IMO) "EBT" system: https://www.hearth.com/econtent/index.php/forums/viewthread/14507/P0/ 

If nothing else, it will provide further confirmation for you of the great deal of interest in having thermostatic control of the woodburning experience which, to me, is the primary benefit of the electronic control you posit.

Enjoy,

Peter


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## begreen (Jan 28, 2008)

Woodrat said:
			
		

> BeGreen said:
> 
> 
> 
> ...



One thought came to me was that modern stoves seem to thermostatically damper the secondary air. The old Resolute dampered the primary air. This seems more useful. After the wood gases are burnt off and the wood is in the hot coal stage, why would it need secondary air?


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## Woodrat (Jan 28, 2008)

[quote author="ControlFreak" date="1201494957"] _We are targeting OEM installations for new stoves._
"Or are you primarily looking at integrating it in at the stove factory?"  _Yes._


Let me preface this by saying that I’m not a technophobe by any stretch.  The fact still remains, however, that having FIRE  in your home is like living with  an “800 lb gorilla”-you have to be 100% certain you’re in control!
    I can understand why you would be interested in getting manufacturers to offer your system, as opposed to marketing it to existing stove owners and I wish you success with that approach. Hope that you can also realize that contrary to popular opinion around here there is a large well-established base of  woodheat enthusiasts out here in the “real world” who have needs and concerns that do not necessarily translate into buying new stoves that are starting to approach prices that could have purchased a decent car not too long ago. 

#1 If you can address the *needs *of people like:   steam man  
 “I do think most stove nuts here would like some kind of remote monitor option possibly to alert for problems and time to fill the stove. “

#2 And the *concerns* of people like:   *sonnyinbc*       "Gadgets are not meant for stoves or inserts. They malfunction, there goes your house.!! 
Right now I’m thinking of greenhouses, where the vents open or close depending on the heat and humidity,Sometimes They Fail!! 
Never,never would I trust one of these things. I want to be able to leave my home knowing the manual controls I use have set the insert to minimum burn,will stay that way. When I go to bed at night, same thing. Don`t want to be tossing and turning wondering if this new gadget is going to malfunction and leave everything “wide open”? 
Maybe you can sell this to the inexperienced wood burners, but not to the rest of that are still (partially sane) ￼
Some of you experienced wood burners may disagree? But remember, I said that those of us that are at least Partially Sane, would never,ever even give this product a -second nod…"

#3 *As well as capturing the attention and interest* of people like: *sixminus1*“The thought of “automating” a wood fire is a little scary, but as you said—if it’s well-tested, and can be completely shut down to allow full manual control when necessary, I think it would be a very cool thing to have. 
A stove with this feature would require the same diligence as bringing fire into your home in the first place—try it out, keep an eye on it, and make absolutely sure that it does what you expect. Don’t leave it alone until you trust it, and even then, don’t completely trust it. It would also require the same type of learning curve that everyone on this forum had with computers (and stoves)—how to use it properly. It’s a tool, it’s a human invention (thus, it’s imperfect), it’s potentially dangerous, and everyone’s mileage will vary. Hey, that’s life.”

If you can do all of the above-- you'll have a hit!  

    I realize that that your main focus will be the number (3) group, I’m just saying that may be enough people in groups 1&2;to keep in mind.  If features of your system could be marketed a “stand-alone” items (maybe designed as you have them to be interconnected later) That might even be a way to gain entry to the existing stove market and get manufacturers’ attention at the same time. Am I making any sense---or just babbling?

      Best wishes---Woodrat


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## kellog (Jan 28, 2008)

Control Freak,

Let me first say that I hope you are wildly successful with your product.  The idea of automatic control of a wood stove is not new but I think it has not been given a good chance to be successful.  Bimetalics are not good enough.  Even the PE EBT system which takes bimetalics one step further with a clever mechanical mechanism is not near perfect (http://www.chimneysweeponline.com/hoebt.htm).

I have a very standardized way of running my stove that I think could be automated easily with electronic controls and do a much better job than I do while saving me the drudgery and time.

Of course, without question, all the safety concerns need to be addressed (failsafe damper closing, over temp alarm, etc.).  

Don’t forget a coal burning step at the end of the cycle (wide open air).

My stove is catalytic and has a primary air control on both sides, a bypass and a damper. That’s a lot of controls.  I don’t think you want to control that system.  Likely it is best to work with an OEM so you can optimize the system and minimize the controls required.

Please stick with it and I wish you the best of luck.


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## EddyKilowatt (Jan 29, 2008)

Dan -

I'll join the others and wish you good luck in developing and selling your product.   I have long thought that a simple control system is a no-brainer for something as unstable as a chimney-drafted fire, and have wondered why this feature has practically vanished from modern wood stoves.  I would love to see it re-appear.   (Ben Franklin would not be pleased that we have made so little progress!)  

That said, I also have to agree with the comments that getting something reliable and fail-safe enough to be safety certified to control fire inside people's homes is going to be a long row to hoe.

I'm an electrical engineer myself, and not an evening passes where I don't watch my stove burn and think about automatic control of the draft.  Thermocouples and PICs and servos cross my mind -- they are what I work with -- but for me there is just too much dissonance between 3.3V power supplies and USB ports on the one hand, and cast iron and firebrick on the other.  

I myself would be happy if stoves just had what TruePatriot describes, a single control that maintains the burn rate at a chosen setpoint over the course of a burn.   That is the inner loop of any control system, and for me it would be plenty.  My gut feel says (contrary to my EE roots) that a simple mechanical system, that controls draft based on flue temp, would do the job -- whether based on bimetal flex or pneumatic pressure or wax-pellet expansion (like a car thermostat) or whatever sort of heat sensor and damper actuator.    A simple one-variable mechanical system with a bare minimum of moving parts, that anyone can understand by looking at for sixty seconds.  I think there's a strong need to adhere to K.I.S.S. both for safety reasons and in order to relate to the woodburner culture that exists today.

But still, I think it is great that you have pursued this and are provoking these discussions.  *Somebody* has to move the industry forward in the areas of performance, safety, and emissions, and it is guys like you who will do it.  Keep up the good work and let us know how it is going!

Eddy


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## KeithO (Jan 29, 2008)

Much as I hate saying this, the easiest way to obtain the failsafe reliability needed would be to add a forced draft blower.  Basically, the connection between draft fan and stove would be so restrictive that there would be no way that the stove could overheat if the draft fan wasn't powered.  Now a simple thermal switch can be added (or 2 in series for redundancy) which cut power to the draft fan if the stove temperature exceeds a pre-determined setpoint.   This setpoint would be higher than the software would allow, thus the failsafe would activate for circumstances where either the controller is toast or something on the sensing side has driven the system towards overfire.  This system can be set up with latching relays so that once tripped, it cannot reset by itself (requires powering down and back up again after the stove has cooled).

On startup, the forced draft would operate at maximum power. At this operating point the blower will be relatively noisy, but it would be tolerable for the short time it takes to establish a hot fire and is particularly useful at a time when the chimney draft is relatively weak.  As the fire gets established, the control system compares the desired heat output (maybe on a 1-20 scale) and regulates draft to stabilize the burn temperature.   With an established fire, the chimney will power the draft to a large extent so the power requirement to the draft blower will be reduced, making it run much quieter. Speed sensing on the draft blower will be required.  Most woodstove users appreciate the peace and quiet of their stove operation, compared to the drone of pellet/corn stoves.

As the fuel burns low, it may be sensible to have a user option to choose NOT to completely burn the coals, but to coast into "standby" mode instead, so that it makes re-starting the fire less problematic.

As I said in the beginning, any cause for an overfire results in the draft system being disabled.    If someone breaks the glass in the door, you're on your own.  Same as what we have today with manual controls.


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## kellog (Jan 29, 2008)

I second Eddykilowatt’s last paragraph.  If someone didn’t work to improve stoves we would still be using Ben Franklin’s original design. 

We now have controlled air intake stoves with secondary burn and some with catalytic elements, some with bimetallic assisted controls, etc.  Our EPA stoves burn much less wood in an environmentally better way.  If we don’t get better, BI types will continue to hound us.  Look at the OWB political issues.  We need to move forward and Controlfreak is one who is trying to help us.  His unit may or may not be the answer but at least he is doing something. Keep up the good work Dan.

If you do what you always did, you get what you always got.


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## ControlFreak (Jan 29, 2008)

More comments: 
"What stove was this tested on? Is the draft spike at the end due to opening up the air control fully to burn off coals? I’m surprised to see no corresponding rise in stove top temp."
This is a Napoleon 1401.  
The change in the draft setting at the end is preparing for the next fire.    Obviously by this point, the draft control no longer has any effect on the amount of heat produced, probably because there's only a deep coal bed and the draft is much reduced to where the air restriction no longer has much of an effect.

As for the issue of safety:  Most of us here fly in planes, and every time we take off, we consider what would happen with a major failure.  I know I do.  Yet most of us accept the risk and fly anyway.  We all run the risk of having our house burn down because we have automated furnaces in our basement.  The risks are kept in check with redundancy and fail-safe mechanisms.  This is a problem that can be addressed with wood stoves, but it will never be perfect, just like your furnace.  We speak of risks of fire, but how many people out there continue to use old smoky stoves that line their chimneys with combustible fuel just waiting for enough heat to ignite it?  What causes chimney fires?  Crappy stoves combined with human error.  What's more common, human error or a control system failure?  The system has never failed and when we have lost AC power it has shut down the stove as designed (before battery backup).  For me, my stove haven't overheated in the last 3 years since running this system.   I overheated it several times per year before using it.  It's not out of the question to load up a stove with the draft wide open and then get an emergency phone call and forget the stove.  I'll take the automation with an over-temperature alarm and a smoke detector sitting on the mantle above the stove.  We all choose our balance between convenience and risk.  I think this is safer as it is now and it will be made even better with the help of all you guys.

Comments?


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## Gooserider (Jan 30, 2008)

I think that the overheating risks are being overstated - yes over-firing your stove might damage it, but part of the entire UL certification process was to establish safe clearances in the event of an over-fire...  Thus I would consider it unlikely that you would burn the house down in the even of a failure of the control system - or at least no more likey than if the HUMAN control system failed.

I would second the earlier suggestions / requests for a nice display equipped, multi-sensor (ideally) temp monitor to start with - preferably with a way to connect to a PC for data logging and possibly remote monitoring.  I'd prefer an ethernet connection, but...

I'd also like to get controllers that would work with my current stove, a VC Encore Cat.  This has a draft control on one side (thermostatic primary) and automated thermostatic secondary, and a "binary" bypass damper with a fairly stiff action.  

I wouldn't try to do a servo on the bypass, but it might work well with a linear actuator, or possibly some sort of geared motor with a spring trip, and a micro switch on each end to control the motor and signal the "state" to the controller.  (which could sound an alarm if unable to set the damper to the desired state)

The primary and secondary dampers could either be switched to servo control, or left as thermostatic, with the possible ability to do a short term "full air" over ride to get a fire started, or char in a fresh load.

Gooserider


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## tkirk22 (Jan 30, 2008)

I think some kind of auto control would be great on a wood stove but I just don't have the confidence to toss in a full load of wood with the air open to full and leave the house. A wood stove is a different beast than my oil burner with a nozzle that mechanically limits it's maximum output. 

If I'm going to be home then I would certainly love to have the stove managed for me.

The unit you are designing is for OEMs. Have you thought about something for the rest of us? Possibly something in the form of a DIY kit that the more advanced user could solder and install himself. That would limit the liability and also give you a good base of testers using different stoves. There seems to be a good amount of mechanically minder people here.

A few guys have mentioned a temp logger in this thread.  Making something like that would be relatively easy and be a good way to get the company name out.

I was thinking about making such a board for my own use but I decided to go a different/easier way for my one-shot logger. Anyway, I'll tell you how I was thinking about making it in case you or someone else here wants to do it. Note: I am not an EE so take the following for what it's worth.

Start with a DS2762 chip. It's cheap, they have free samples, it will read a thermocouple, it has a built in chip temperature sensor, and it has some built-in memory. There is also an alarm function on the chip that may be interesting but I haven't looked into that.  Anyway, run the chip input through a multiplexer to read 4 thermocouples. Now use a small cheap micro controller to drive the multiplexer, read the thermocouples, and upload the temps back onto the DS2762 chip's memory. Run 2 wires out of the box to a $26 USB 'dongle' on a PC. Those same 2 wire also power the box. From there on out it's software. With 4 thermocouples and 2 power wires the biggest part of the unit would be the wire connector. I think it could be built the size of a cardboard matchbox (or 2).

I am working on a setup similar to what I outlined above but it's hooked up to an $80 dollar micro computer using a USB 'dongle' and it uses off the shelf components. The stove thermocouple is being read by a DS2760 chip with type K thermocouple wire. (graphs below) For you eagle eyes out there, It's not hooked to a stove yet. I had the thermocouple measuring my computers heatsink at first and later switched it to measure my beer temperature. Then later is was measuring ice water. The stove thermocouple is not compensating for the chip temperature yet so it's is about 20 degrees off on the graph.  Oh yea, the basement/office temp is accurate and it is that !@#$%^&* cold. The other graph is logging radiation clicks in my basement. That's the main reason I started working on a logger.


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## ControlFreak (Jan 31, 2008)

"The unit you are designing is for OEMs. Have you thought about something for the rest of us?"  

Yes, eventually.  First we need to establish a reliable name.  That would be very hard to do, starting out by sending off kits to people with various skills and stove configurations.

One way you can help is by going to our website and taking our survey.  www.inveninc.com   Look for the white "Take Our Survey" link at the lower left.  Gathering this data is essential to a successful launch.  Oh by the way, there will be a drawing for an Ipod Shuffle when the survey is completed.  The winner will be announced here, so you can be sure that we're not just "blowing smoke."

Dan


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## Rob From Wisconsin (Jan 31, 2008)

Being an Engineer that has developed products that have been under the scrutiny of UL/CSA/CE,
('nuff said of my credentials)......
Most safety underwriting agencies don't fully trust electrics/electronic in a safety critical operation.
They tend to "smile" at mechanical safety interlocks, that in turn cause the energy source to fall to
its lowest possible potential, if immediate injury/harm can reasonably be prevented. For example,
spring loaded solenoid valves that return to their resting "closed" position when power fails, or any one of a set of "critical" faults occur - overtemp, controls self-check failure, etc.....
Also, in extreme critical control, redundancy is required. Such an example would be if one of the overtemp. sensors failed (regular or backup), the controlling unit would "fail" & remained de-energized until both regular & backup sensor were restored to their "normal" operating states.

In all sincerity, your proposed system sounds like a fairly easy system to implement & design
"fail safe". The only potenial problems I see are the "nuscience" shutdowns that will likely occur
from a system that may need to be "over-safe" (i.e. - pellet stove problems). But w/ time,
even the Pellet Stove industry seems to be getting it right.......

Hope this gets you in the right direction.....
Rob


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## Andre B. (Jan 31, 2008)

Kirk22 said:
			
		

> I think some kind of auto control would be great on a wood stove but I just don't have the confidence to toss in a full load of wood with the air open to full and leave the house. A wood stove is a different beast than my oil burner with a nozzle that mechanically limits it's maximum output.
> 
> If I'm going to be home then I would certainly love to have the stove managed for me.



When I think about designing something like this, here are some of the first things that come to mind.

There should be two manually set air controls.
One in parallel with the automatic control, this one is used by the operator to set the minimum airflow.
And a second in series with them, this one is used to set the max airflow.
This way the automatic control can be limited on both min and max airflow by the operator.

Then how to make things fail safely.
First a spring on the auto air valve to close it in case the power drops out do to an ice storm or some sensor trips the E-Stop system.
Then I think, springs eventually fatigue and break so change it to a weight, gravity never fails.
Now need some way to physically disconnect the servo from the air valve when the power fails, otherwise the weight needs to be enough to back drive the unpowered servo, which means the servo will be constantly using enough electrical power to hold up the weight, can't have that in something that may well be running off batteries.  So put an electromagnet between the servo and the valve, still needs constant power but not much.  It does require that the servo run down to valve closed position on power up to pick up the valve, but then it is not a bad idea to do a range of motion and limit switch test anyway.  Should also monitor the servo current and report a possible problem.

Etc..


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## ControlFreak (Feb 5, 2008)

Do you think that people who heat with wood have an aversion of mixing high-tech stuff with the low-tech tradition and simplicity that's prevalent in wood stoves?

Dan


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## Woodrat (Feb 5, 2008)

Quite likely ---- esp. "older" ones.


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## singed (Feb 5, 2008)

Well, I'm here because I went out searching for "wood furnace" "control" OR "controller" and was disillusioned. 

When I found this thread, I had to sign up, log in, and say, "Go, Dan, go!"

We just bought a house west of Madison, WI. It has an owner-built wood furnace as a secondary heat source in parallel with an LP.

It's an odd duck. There is, what I've come to understand, a line-voltage thermostat in the first-floor hall which powers a rotisserie motor rigged to lift the air draft to full-open  when heat is demanded. The lever arm on the motor shaft which lifts the draft gate also serves to stall the motor when it hits the "limit bolt." 

A second plenum-mounted thermostat actuates the blower when plenum temperature hits the setpoint. Meanwhile, the rotisserie motor stays in stall mode until the hallway thermostat hits its setpoint and drops power.

Immediately, I wondered why-in-the-world there wasn't a controller to read all the inputs and control the draft-door position in a closed loop with the flue (and perhaps, I thought, the plenum) temperature.  Immediately after, I started dreaming about a design.

I appreciate the wisdom of you wood-stove-loving aficionados who have distilled that wisdom from years of observation and experience. You need to tell me how to run a furnace because I am an idiot (and have the PhD to prove it), but my point is that--more and more of us are going to have to try wood to cut our energy costs--and the normal distribution being what it is, the preponderance of us are not going to love it.

So, we're going to burn green wood and run our stoves way too hot and just generally be a danger to ourselves and our neighbors. 

An acquaintance has regaled me with the wonders of his pellet stove ("No ash! Think of it! 100% burn!") and while looking for that elusive after-market controller, I heard of Greenfire (http://www.greenfirefurnaces.com/products.html) which I took to mean wood-log combustion can be very efficient too. 

That's what brought me to thinking about and looking for a controller to optimize the process, and now I'm fairly convinced from earlier posts that, having set a match to the wood, I mostly want to make sure the fuel burns most completely. It will be nice if it can be damped down to reserve some of the fuel for later if it's not needed immed., but I'd rather it be burned up for the sake of clean air than left half-unburned going up the chimney.

Echoing what was desired earlier re: retrofit kits, I'm reminded of my first computer (a Zenith Z-100 from "Zenith [TV] Data Systems"). ZDS published a magazine for their customers that had articles on "things to do" with, and to, your Z-100. It came with as I recall 192K (that's 'kay') of RAM, but one of their engineers explained how he'd managed to use 256K chips to expand the memory to 768K. (I'll tell you we wet our pants at the prospect!)

But here's the kicker: at the end of three issues, I had the complete set of instructions, with photos, of the modifications, and one weekend I proceeded to take out the "motherboard" (new term for me) and CUT traces hither and yon with an Xacto knife while BENDING OUT PINS from specified ICs and soldering jumpers all over the place. I put it back together without a second thought and powered it up and began using my new gofast machine. It was only years later (I had been in my 20s at the time) that I realized what a delicate instrument I'd been fiddling with.

But, being the idiot that I am, I desperately want to drill holes in my furnace, bolt things on the side and top of it, wire in jumpers and have something that behaves like a decent human being for once.

As far as cost goes, you can sell me ANYTHING at ANY PRICE, *after* you _prove_ to me that it's actually SAVING me money over N years. The pellet-stove guys have my attention that way.

Thanks for all the great comments in here.

Go, Dan, go! (One way to save costs: move from MA to IA...) :^)


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## Gooserider (Feb 5, 2008)

Welcome to the forums Singed, this is definitely the place to learn about messing w/ wood burning...  If you haven't gotten to it yet, it sounds to me like you'd be interested in talking to the guys over in the "boiler-room" forum, as they are more the experts on heating with central systems - as opposed to the Hearth room which is more about stoves, etc...  They are also doing quite a bit with controls and such - lots of good info there.

Gooserider


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## BrotherBart (Feb 5, 2008)

Woodrat said:
			
		

> Quite likely ---- esp. "older" ones.



Yeah you got that right. Those old guys just can't grasp new technology.


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## swestall (Feb 5, 2008)

Hey BB, what are we going to do if we can't adjust the air?


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## singed (Feb 5, 2008)

Thanks, Gooserider. It's good to wake up among savants.

Rooms? You say there's rooms?! :^)

I'll wander over.


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## ControlFreak (Feb 5, 2008)

Hey Singed,

I grew up over there in Watertown, WI.  Graduated from UW Madison with a EE in 83.  Maybe we'll see you this summer while we visit.

Dan


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## singed (Feb 6, 2008)

Hey, Dan, I PM'd you. Yeah, come see me at UW.


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## jotul8e2 (Feb 6, 2008)

As it happens, I too have been wondering about this issue.  When it comes to automated controls, compared to a wood fire burning oil, gas, or even coal is child's play.  Microelectronics undoubtedly make it tempting to think it can be done.

However, once you have decided that a stove that plugs into a wall outlet is acceptable (and many inserts, and all outdoor wood furnaces are electrically dependent already), then why not take the leap and hook up to a gas supply (lpg or propane) as well?  A very small, microprocessor controlled gas burner in the secondary combustion chamber, combined with automatic primary and secondary air controls (possibly mechanical?), could ensure efficient, clean burns for all those times when the wood, the loading, the temperature, or whatever, is not optimal.  The suggestion made above that forced air may be required is likely correct.  And when conditions will not allow a seconary burn (wood too green, too wet, etc.) it could just shut off the air intake and allow the fire to go out, rather than sit there and smolder uselessly.

Something along these lines could make those dirty, inefficient outdoor wood furnaces far more appealing.

Mark


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## Gooserider (Feb 6, 2008)

No thanks...  I burn wood in order NOT to burn gas...  I don't want anything to do with a gas burner in the wood burner as that would defeat the entire purpose...  

I suppose there might be something to be said for having a small gas burner to make starting fires easy, but I'm not sure just what, as once you know how it is almost trivially easy to start a fire w/ newspaper and kindling...

Gooserider


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## jotul8e2 (Feb 6, 2008)

Gooserider said:
			
		

> No thanks...  I burn wood in order NOT to burn gas...  I don't want anything to do with a gas burner in the wood burner as that would defeat the entire purpose...
> 
> I suppose there might be something to be said for having a small gas burner to make starting fires easy, but I'm not sure just what, as once you know how it is almost trivially easy to start a fire w/ newspaper and kindling...
> 
> Gooserider



I'm not thinking of a gas fired appliance with supplemental wood heat.  I'm suggesting the possibility of a small, electrically ignited, temperature controlled flame source to ignite secondary gasses earlier and more consistently.  A little gas (or oil, I suppose), to make a wood appliance function more or less automatically could be attractive in some applications.  In fact, some outdoor furnaces already use gas or oil as a backup heat source.  Why not take it a step farther and use a trivial amount to acheive a much larger btu output from the wood fuel?  If someone burning six cords of wood a season could get the same btu output for, oh, say five cords and five gal. of propane, then why not?

Of course the answer may well be that it would not work that way.

I should have noted above that I personally don't want such a furnace either.  My stove has to function independently of any inputs beyond wood and my time.  But I can see where such an automated wood fuel stove could be desirable.

Mark


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## ControlFreak (Feb 6, 2008)

"why not take the leap and hook up to a gas supply (lpg or propane) as well?"

I think it will come down to cost.  Adding such a thing is certainly possible, and I have given this some thought, but in my opinion the complexity + cost vs benefit makes this impractical.


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## MishMouse (Feb 6, 2008)

There is also another thing with adding propane to a wood stove, especially if your stove over fires, or the ash and heat cuases the connection of the propane to degrade.

B O O M !

No more heating problems....  :lol:


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## tradergordo (Feb 8, 2008)

jotul8e2 said:
			
		

> As it happens, I too have been wondering about this issue.  When it comes to automated controls, compared to a wood fire burning oil, gas, or even coal is child's play.  Microelectronics undoubtedly make it tempting to think it can be done.
> 
> However, once you have decided that a stove that plugs into a wall outlet is acceptable (and many inserts, and all outdoor wood furnaces are electrically dependent already), then why not take the leap and hook up to a gas supply (lpg or propane) as well?  A very small, microprocessor controlled gas burner in the secondary combustion chamber, combined with automatic primary and secondary air controls (possibly mechanical?), could ensure efficient, clean burns for all those times when the wood, the loading, the temperature, or whatever, is not optimal.  The suggestion made above that forced air may be required is likely correct.  And when conditions will not allow a seconary burn (wood too green, too wet, etc.) it could just shut off the air intake and allow the fire to go out, rather than sit there and smolder uselessly.



Believe it or not, this has actually been invented already.  I stumbled across it in a patent search I was doing.  
A guy from the EPA, Robert Hall, has a patent called "Woodstove for heated air forced into a secondary combustion chamber and method of operating same 

Abstract
A resistance heater heats air forced by a fan into a woodstove secondary combustion chamber having an ignitor. The fan, heater and ignitor are controlled by a temperature sensor for gas flowing from a primary combustion chamber to a secondary combustion chamber. Two ignitors, extending through the stove back wall into the secondary combustion chamber, are controlled by the temperature sensor. 

Anyway, in his patent, he mentions:

"*Other techniques for sustaining combustion in the secondary combustion chamber have involved the use of a natural gas powered flame and electrical ignitors; see Spolek et al., "Secondary Combustion in a Dual-Chamber Woodstove,"* ASHRAE Transactions Vol. 91, Part 1, pages 1138-1146, 1988. Laboratory measurements of woodstove emissions using natural gas powered flames have demonstrated a substantial decrease during limited testing. However, experimentation with natural gas powered flames was suspended because of practical problems associated with supplying an external natural gas source to a woodstove. In experiments we conducted with electrical ignitors, wherein the ignitors were located on the secondary combustion chamber outside wall, it was found that the electrical ignitor did not result in complete combustion of products in the secondary chamber. "

An object of the invention is to provide a new and improved dual chamber woodstove having secondary chamber combustion control and method of operating same. 

It is another object of the present invention to provide a new and improved dual chamber woodstove having a secondary combustion chamber wherein the stove is efficiently operated and emissions, including particulates, are substantially reduced, even though fuel is being burned in a primary combustion chamber of the stove at a medium or low burn rate. "


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## cbrodsky (Feb 13, 2008)

Dan,

Very interesting - this is something we've discussed on hearth.com many times in the past - making a wood stove almost as idiot-proof as a pellet stove.  It looks like you've spent quite a bit of time on this and it seems like a very professional product that no matter where it goes, would certainly have a niche market on hearth.com among the many engineers.

What price range are you targeting?  The survey seemed to indicate you are looking at $400+ as the lowest option, which could be a significant challenge.  I think many of us technical types would be interested in this but it probably needs to be a cheaper product for broad mass market adoption - it will definitely be a challenge to get people to mix high tech controllers with wood heating.  I have been looking at spending $100 or so for a digital thermocouple with alarm for overfires and would gladly add $100 more for a draft control.  But I suspect many people would weigh the cost against a bimetallic system with a calibration adjustment and say that it's "good enough" for $10.  I don't think I could justify $400+.

The auto-calibration idea for the draft controller could be really helpful for aftermarket applications.

I noticed you list this as a "patent pending."  I was curious and took a look but didn't see a published application yet on the USPTO site.  I'm curious which aspects you believe are novel, presuming you've already filed to protect those claims.

-Colin


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## begreen (Feb 13, 2008)

CF, I understand the nature of the product proposed is to control the stove, you might also want to consider an offshoot product from this technology. I think you could do well to produce a good stove monitor. I other words, the same device but without the output side servos and air controls. If it can be tied wirelessly to a computer, even better.


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## ControlFreak (Feb 13, 2008)

Guys,

The monitor idea is not something we had thought of.  However, this is a subset of SmartStove.  So, considering how easy that would be to do, it would make a lot of sense to offer a stripped-down version which is a thermal monitor with settable alarms.  I don't see any reason why we wouldn't do this.  We will be discussing this for sure.  

Dan


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## cbrodsky (Feb 13, 2008)

ControlFreak said:
			
		

> Guys,
> 
> The monitor idea is not something we had thought of.  However, this is a subset of SmartStove.  So, considering how easy that would be to do, it would make a lot of sense to offer a stripped-down version which is a thermal monitor with settable alarms.  I don't see any reason why we wouldn't do this.  We will be discussing this for sure.
> 
> Dan



I would definitely be interested in the $150 or less range.  And I think it may help you get higher volume sales to help bring costs down for active controls.  Make sure you consider catalytic stove applications as well - catalytic users are often more interested in maximizing efficiency.

-Colin


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## Gooserider (Feb 13, 2008)

ControlFreak said:
			
		

> Guys,
> 
> The monitor idea is not something we had thought of.  However, this is a subset of SmartStove.  So, considering how easy that would be to do, it would make a lot of sense to offer a stripped-down version which is a thermal monitor with settable alarms.  I don't see any reason why we wouldn't do this.  We will be discussing this for sure.
> 
> Dan


I would second the interest, and also suggest doing a search on past threads, it's been a while since the topic has come up, but there have been several previous discussions of desirable features and so forth.  There is a definite market opportunity here as I don't know of anyone offering a product that really matched up with what a lot of us seemed to want.  I would suggest trying "Digital Thermometer" as a search string, mostly in the Hearth Room and Gear forums.

Quick summary as I recall it - 
2-4 inputs, probably "Type K" thermocouples
Large display, LED or backlit LCD, able to be read across the room...
AC power (wall wart?) w/ battery backup, no automatic shutoff
Alarms for over-fire temps, and possibly low temp / add wood
Some sort of ability to output to a PC - I prefer wired ethernet, other folks liked USB or Wireless, needs to be in a documented format so that any O/S can use it, not just Micro$oft

Gooserider


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## mayhem (Feb 13, 2008)

ControlFreak said:
			
		

> To all,
> 
> We are a small company in MA that has developed an intelligent electronic wood stove control system and would like to hear your feedback.  Please, this is not spam, but intended to probe a subject that I rarely hear about -- combustion control in wood stoves.
> 
> ...



I hope this helps.


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## scotty (Mar 2, 2008)

Colin, the "novel" test was degraded some years ago. I think that you know that, but I thought I'd elaborate for those who don't. Today a patent doesn't have to be quite as new or unique as was once the case....it can simply be an improvement on an existing process. In other words, a unique manner (proprietary electronic circuitry) of achieving a desired effect (combustion control) would be very patentable. The test for "improvement" is that the new process solves a "known problem".

BTW, At one time the patent office preferred that the inventor submit a working model with the patent application. They can still require a model, but now they prefer drawings and data as they are running out of storage space.
......MORE STORAGE SPACE...now that would be a great invention!

     scotty

>I noticed you list this as a "patent pending."  I was curious and took a look but didn't see a published application yet on the USPTO site.  I'm curious which aspects you >believe are novel, presuming you've already filed to protect those claims.

-Colin[/quote]


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## scotty (Mar 2, 2008)

[quote author="ControlFreak" date="1201303477"]To all,

We are a small company in MA that has developed an intelligent electronic wood stove control system and would like to hear your feedback.  Please, this is not spam, but intended to probe a subject that I rarely hear about -- combustion control in wood stoves.

To kick off the discussion, I'll ask several questions:

1.  Why hasn't this existed until now?  We have some ideas, but want to see what you guys think.  We already know about the use of bimetalilc springs to do this, and using a timer to close off a start-up draft control, but what about an electronic system that is intelligent and offers flexibility and adaptability?

Most of the time the people who have wood stoves actually enjoy operating them manually. The same preference leads to horseback riding, bicycling or sailing rather than cars and power boats. But there are times when even the most traditional manual stove operator would enjoy an automatic system  in the same way that we use our cars or sometimes put a motor in a sailboat. The bimetallic spring models which I've used (Ashley & VC) were a huge improvement over the purely manual stoves. But they were also very inexpensive and easily designed to be intrinsically safe  - that is, any failure of the controller shut the stove down.  I'm sure that Electronic Combustion with feedback would accomplish the same thing or better and I for one would probably try it.  As to "why hasn't it existed until now?" well, electronic control is still a fairly new field and there are a lot of good ideas that simply haven't been built as yet. 

2.  Have you ever asked a stove store about something like this?

No, we are part of a rural population well versed in wood burning and tend to rely more on local knowledge than on retail stores. 

3.  If you were purchasing a new stove, would you purchase this if it was an option?

It would be one of the factors, but not the most important one. A retrofittable device with components in the combustion air intake duct as well as in the stove pipe itself would not be dependent on stove brand.

4.  If you were to choose between two different, but comparable models, would this feature cause you to choose the one with the controls?

No, there are bound to be more important differences between two stoves. I would rate this feature below several favored construction features, burn geometry, cat or not, and wood loading. For me it would be on the level of importance that I assign to porcelain trim, ash removal, or side warmers. A retrofittable option would be much more appealing, and in fact would be appealing even though fairly expensive. 

5.  Do you ever overheat your stove by forgetting to close the draft control?  If so, how often.

No,  though I do worry about it happening when guests use our house

6.  Do you know of anyone who has had a fire because of an unattended wood stove?

No, not a structural fire; not of my own direct experience. ...which is sort of surprising given how common wood stoves are in this area. However, I am exempting chimney fires which are not uncommon. 

What other questions are there??

Well, you haven't asked if such a device would appeal to a dedicated traditional wood stove user. I can only answer for myself in that I tend to buy and try the new techo-toys that come on the market just out of curiosity. Perhaps they will add something to our live - or not - but how do I know if I don't try them? 

BTW, nice web site. 
        scotty,   Boulder, Colorado.


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## RegencyNS (Nov 25, 2008)

ControlFreak,  Any update on your device?  Where can I order?


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## scotty (Nov 27, 2008)

Yeah....I've got the same question as shawn. Hey. Control Freak.... are you there? Was it all just a pipedream? 
     scotty


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## rob bennett (Nov 27, 2008)

The website is heavy on the concept but lacking detail.  I've seen sites and threads like this when someone has an idea and they have yet to prototype it.  Basically it looks to me like it was a "I have an idea, but have yet to pursue a prototype, should I go on?"  If it is a legitimate product, I'd think that there would be SOME type of data to support the product.

And if it were my website I'd drop the summit on the homepage.  It more or less has a lot of automation going for it anyway.


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## scotty (Nov 27, 2008)

It probalbly takes more than a year to prototype and make such a unit. Or maybe I scared him off when I filled out his questionaire 5 or 6 messages above this one. I just re-read it and it seems like a valid questionaire....good info.  Can I get someone to comment on his questions and my answers?
       Thanks,   scotty   Boulder, Colorado @ 7000 ft.


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## Gooserider (Nov 28, 2008)

scotty said:
			
		

> It probalbly takes more than a year to prototype and make such a unit. Or maybe I scared him off when I filled out his questionaire 5 or 6 messages above this one. I just re-read it and it seems like a valid questionaire....good info.  Can I get someone to comment on his questions and my answers?
> Thanks,   scotty   Boulder, Colorado @ 7000 ft.



I think his questions are reasonable ones, and your answers are not all that different than what I'd give, especially the idea of wanting a retrofittable device to go on a stove that already met your desires in other respects, as opposed to it being a primary purchasing choice driver.   The trouble is that I would think doing a retrofit design for anything beyond temperature monitoring would be incredibly difficult - just think how many different designs there are for air controls as one potential challenge...  (I'd still be interested in an electronic temperature monitoring setup, but don't have any real interest in the control side...)

However, if I were trying to develop a marketting plan, or decide whether to go to the trouble of prototyping a unit, the answers are not ones that would encourage me, and some of the other answers that CF got even earlier in the thread were even more negative in the sense of not being interested in the potential product...

I did just check CF's user info, he's still active on the board, and has posted within the last few days, but looking at the threads and his comments in them he didn't have anything to say on this thread's topic - don't know if he is no longer doing anything on it, or just not following this thread any longer.  (BTW, you can do this, as well - it didn't take any "secreret mod powers"  :coolsmile: )

It might be worth sending him a PM to see what the status is... 

Gooserider


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## kenny chaos (Nov 28, 2008)

I would LOVE to have something to at least help with the burning cycle on my Liberty.  It is very easy to control but I need to be here to run the controls when I should be focused out on the farm.

You gotta understand that I heat part of a 188 yr. old stone house that virtually sucks the heat right out of the stove.  Once it's up to temp, I can sometimes cut down on the primary and it will sometimes hold that temp for an hour and a half before it starts dropping off and I gotta keep adding more and more air to get the most out of it.  Yes I can get 20 hour "burn times"  where there's enough coals for a relight but if it ain't at 650, the house ain't at 65.

I actually spent a couple of hours the other night researching thermal controllers but I don't have the smarts to figure something out though I wouldn't hesitate to put it together if I knew how.  I have more stamina with my hands than my head.

As far as dangerous gadgets go, I got a $4000 oil guzzling blast furnace that'll run 24-7 without the woodstove and I only see that once a year.  Usually in the late summer when it's not even running.

I'm not scared of new technology but I am very wary as to its usefulness for me.

To Dan if he's still watching:  A retro for me please.  I don't expect to buy another stove in this lifetime.


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## Gooserider (Nov 28, 2008)

The problem is that the really hard part IS doing the control retrofit...

Sensors are easy...  There is a question of what to measure, where to put them, how to interface them to the data collection unit and so forth, but there are lots of options, all of which are pretty simple and off the shelf hardware.

The controller "brain" itself is also pretty easy - if you can come up with a set of measurement based rules (If condition X then do action Y) then it is a fairly straightforward thing to program them into a PC.  If you want to get fancy, you can then burn that program into an embedded system, or other specialized hardware, which again has complications, but nothing to difficult.

The tough part is translating the desires of the "brain" into actual control operation - pretty much every stove is different, with a different set of controls that operate differently...  How many different styles of control are there - do you push, pull, turn (which way, and how much), slide sideways or up and down, etc? each one would need a different sort of actuator - How hard is it to move the control?  How will you mount it?  Does the area around the control get hot?  How much insulation will the actuator need to keep from overheating? Lots of questions, each one with different answers depending on the individual stove...

Once you have the one off control designed and built (a challenge in and of itself, where will you get the stoves needed to develop on?) how much are you going to have to pay for testing it?  How do you ensure that if it fails, it does so safely? 

I think this is perhaps the reason why CF doesn't appear to be persuing the problem any more - it doesn't appear to be something that has a profitable answer.

Gooserider


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## kenny chaos (Nov 28, 2008)

Mr. Goose- Did you take the test in the Ash Can?


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## Gooserider (Nov 28, 2008)

kenny chaos said:
			
		

> Mr. Goose- Did you take the test in the Ash Can?



What test in the AC?  (I normally stay out of that area, keeps me out of trouble...)

Gooserider


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## kenny chaos (Nov 28, 2008)

I don't like it there either but if my posts don't get deleted, that's where they end up.
In the Ash Can: "OK, folks, what do you know about the Real America"  Craig wants to see who's the smartest and so far I'm winning.


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## kenny chaos (Nov 28, 2008)

I'm definitely winning.


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## kenny chaos (Nov 28, 2008)

Well I got a job offer so that's a win in my book.  It may not mean anything to you.


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## ControlFreak (Dec 1, 2008)

shawnmd said:
			
		

> ControlFreak,  Any update on your device?  Where can I order?



Hello Shawnmd,

Thanks for your interest.  Responding to your question, and to others:  This is well beyond the first prototype (we're at hardware revision 4.1), and is currently being evaluated by one of the larger stove companies.  Various revisions of SmartStove have been running my Napoleon 1401 24/7 for several years and the latest revision is running an everburn product nicely.  The current hardware is one generation beyond what's running on my stove -- the latest revision brings features that are suited for cat stoves -- something not needed with the 1401.  

This is no pipedream.  Developing a product is one thing, but getting it into the marketplace is another, especially with a new technology.  The latter is more difficult than the former, especially with a tight budget and time constraints.  Feel free to send me a PM if you want to discuss this more.

Dan


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## jackiec (Dec 2, 2008)

ControlFreak said:
			
		

> shawnmd said:
> 
> 
> 
> ...


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## Gooserider (Dec 3, 2008)

jackiec, I deleted one of your posts as it was a duplicate - just keeping things neat...

One minor suggestion - when you are including a quoted bit, it helps if you pay attention to the "tags" around the part you are quoting - they will have two square brackets "[]" with something in them, like "quote" at the beginning, of the quoted bit and another pair at the end, with the same thing preceded by a forward slash at the end - like "/quote" (sorry for the cumbersome explanation, but it's hard to put this stuff in a post without having it be turned into a display...)

Anything between the tags ends up as part of the quote, and anything outside doesn't...  It is easiest to follow if your comments are outside the quoted bits  (Same thing applies to any of the other text enhancements, it just has different stuff between the square brackets)  You can also break up a quote by putting in more tags (always in pairs) and do other fun things like nesting and so on...

If you aren't sure your message will look the way you want it to, you can hit the "Preview Post" button at the bottom of the entry screen instead of the "Submit Post" button, and you can see what it will look like, and have an editing box to fix any problems.  Just be sure to hit the "Submit Post" button as your last step or your post won't ever appear.

Not a big deal, but it makes your messages easier to read.

Gooserider


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## ICY99 (Dec 3, 2008)

ControlFreak said:
			
		

> To all,
> 
> To kick off the discussion, I'll ask several questions:
> 
> ...



Dan, here are my thoughts:

1. I think there probably is a market for this, but it is increasing the complexity quite a bit.  

2. No. I would not be interested.

3. No. I would definitely steer clear of any electronic control devices on a wood stove.

4. I would choose a model with PASSIVE, MECHANICAL control rather than electronic control.

5. Never. But I agree that overheat is a possibility.

6. I do not know anyone personally.


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