# not your grandpa's garn



## TCaldwell (Jan 15, 2012)

Here are some pics of my modified garn, o2 controlled. I abandoned the combustion air inlet, fabricated primary and secondary inlets that terminate in the same locations in the firebox. On the other end they are ducted to 4 inch primary and secondary air dampers with belimo modulating actuators.  to start from the beginning, the o2 sensor relays feedback to the fluegas analyser converting a signal input to the cybocon ce model free adaptive controller, that calculates and sends a output signal to the belimo actuators/dampers that creates new input for the o2 sensor to transmit. this happens once per second. The desired result is to maintain a setpoint of 7%o2 residual in the fluestream.  This is basically how most all o2 controlled boilers operate, just not done with a garn before. It took alot of trial and error, and hundreds of burning hours programming the controller to get robust predictable results. I ran out of picture space, but will post graphs of o2 trending of a stock burn and a o2 controlled burn. I have other mods as well, a tank mix loop that homoginizes the water temp as long as the inducer is on piped with a dirtcal. The garn supply water temp is mixed with a modulating 3 way valve behind the boiler that is next to the flatplate hx in the garn barn that i built this spring by myself.


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## Gasifier (Jan 16, 2012)

Wow TC. Nice work man. Thanks for sharing. That sounds like you did a lot of work to it. What made you do the modifications to the Garn? Looks like from the number of responses you have so far that everyone was watching the Giants spank the Packers!  :ahhh:


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## heaterman (Jan 16, 2012)

I've been waiting to see this.  Looks like waaaaay too much fun to me.  I wish I lived closer to you so I could play with it too.

Any idea what numbers you're generating for Efficiency and CO?


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## deerhntr (Jan 16, 2012)

Tom,

How are things going? Looks good from here. 

Very impressive! Of course I have a couple of questions. Why did you decide to bypass the stock primary combustion inlet?
Was it not able to provide sufficent fine control to maintain the 7% o2 setpoint, or was it to provide more o2 during the peak of the burn cycle?
From your pic, the mod for the air inlet is obviously at the door, are you then using the stock inlet as your secondary inlet?

From your plots, it appears as if you have very good control to the set point.
What is the theory behind your mod? Is is that by maintaing a constant o2 %, that will maximize the burn and heat transfer during the complete burn cycle? Also that is very interesting how the o2 get starved at the peak of the burn cycle when you burn without control.

Just a couple more questions. Could you post your pics, larger? 
They come up as thumbnails when selected, and my tired old eyes can't really enjoy the great work you have done. And, is that "heaterman's" garn blanket you have your beast wrapped in?

By the way, your garn barn looks nice! How much time do you spend in that rocking chair!


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## Sawyer (Jan 16, 2012)

Very nice job Tom, wish I were able to see this in person. I look forward to your graphs. How does the increased O2 effect the flue temperature at peak burn?

I use Firefox for a browser. I can zoom in on your photos which helps; at 150% level the image is still quite clear.

If this system lets you use the rocker I need to change my system also!


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## DaBackBurner (Jan 16, 2012)

DANG! Now I have combustion efficiency envy! GREAT work! Looking forward to see the numbers as well.


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## thecontrolguy (Jan 16, 2012)

Hey TC! Nice work.  Not meaning to be greedy, or anything, but when you set up that graph you promised, could you (please) put the control output (or damper position) on the graph also?  I am interested in how the control programming handles startup, transients such as opening the feed door, and what you do as the O2 sensor degrades or otherwise gets fouled by soot.  Is there a software loop for default open-loop control if the sensor is pooped?  Cheers and congrats.

Edit:  Also, could you indicate what sensor you are using and if it is preheated?


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## deerhntr (Jan 16, 2012)

Guy's

He already posted a couple of plots. Check this thread.https://www.hearth.com/econtent/index.php/forums/viewthread/88701/


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## TCaldwell (Jan 16, 2012)

Sorry for the quick explanations last night, limited time. The garn is first wrapped with 3 inches unfaced fiberglass, used self sticking insulation pins/washers, then 3 inches of closed cell spray foam except for the front and flue area, then a 4 inch layer of metal bldg insulation that has a tough gym-guard scrim covering. The combination seems to work well with no measurable heat radiation. The front of the garn has a 4 inch layer of roxul with duct metal covering. The back of the garn around the flue has a roxul surround covered with sheet metal. I also installed a tank mix loop, installing 2 two inch nipples in tne top of the garn  one on either side of the manway cover, the intake is in rear and pulls low from the bottom of the tank and discharges that about 12 inches below water level in the front at a rate of 25gpm only while the inducer is powered. Usally if the front temp gage [old style] reads 180 , five minutes after a start of burn it will drop to 160, keeping the tank temp homoginized as it is being recharged. In the mix loop before the circ I have installed a calefi dirtcal, that is also why i pull the water from the bottom of the tank to pull in any localized debris. The primary and secondary air ducting, of wich due to limited number of pics in the post is the same as the primary shown but in the top of the firebox, same as stock spots. I used a 4 inch round oval aluminized exhaust pipe so I could perforate the air collar without going waterside. the stock combustion air inlet was plated shut thus making the air collar ineffective. I kept stock inducer and still maintain approx 300cfm at ambient air temp. The exhaust tubing came from spin tech automotive. This way i was able to use the nice garn door, but fabricated a more positive latch. Yes the intake mods allow independant control of the primary and secondary air. In principle with a batch burn there is no combustion control, however martin has done a great job of balancing the air and combustor design to be able to accomodate a very clean burn with no moving parts. this comes with it's own burning charachterics as shown with the graph, under aired in the beginning and overaired for the latter part and still maintain one of the cleanest burns available. This curve is dictated by a very fast hot burn, martin's intent. My thought was more to control the combustion to a stiometeric value for wood [7%] throughout the burn, and still maintain a relatively high output. In theory i am retarding the burn at first, relaxing in the middle and forcing at the end by using the stock inducer and not a variable speed setup.  The fire starts hot with all primary air, gasification within 3 minutes [1200deg secondary burn temps] then reduces primary and modulates secondary to maintain setpoint, at the end with a o2 level higher than setpoint it closes secondary and all primary burning the coals. This process typically does not go beyond 1800deg in the secondary burn chamber, usally between 1400-1700 for most of the burn, with one turbulator in the last pass flue temps 260-310, the burn seems to last slightly longer also. This flue temp is read from a type k in the first section of class A after the garn. I have a testo portable fluegas analyser that I will measure other fluegas compounds in the next few days and post results. Just a side note, the red line in the o2 controlled graph is damper output with the percentages of the secondary damper represented on the right side of the graph. the secondary damper is closed at beginning and end of burn, the primary damper operates in oposition to the secondary. This shows a high output of 65%, thus the secondary damper is open 65% and the primary is closed 65%, the highs and lows to control vary also on wood species and mc. As complicated as this seems , in the world of combustion control this is a relatively simplistic approach, the froling for example is much more sophisticated and refined, but does not have a 400k btu output.  The barn 16x24 took me about 3 months of weekends, with the infloor tubing, Oh I installed a combustion air intake fan with damper in the room that is controlled by the inducer circut.


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## heaterman (Jan 16, 2012)

It will be interesting to see how the numbers compare with the test results I have from Garn on a model 2000.  The efficiency number they got in the actual dilution tunnel test are at the point that you couldn't go much further without condensing and emissions are very very low. If I can find them I'll post them up here on this thread.


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## TCaldwell (Jan 16, 2012)

Control guy, the o2 sensor is a bosch lsm11 4 wire wideband industrial sensor, 30watt heater and a 0-1v control signal. The sensor threads into the probe that has particulate screens inside, however before every burn it takes less than a minute to clean it all with compressed air., this makes life predictable for the cybocon ce controller. Russ, thanks for the link. keep the questions coming, as it is too cold to be outside today. the controller has a process value alarm that initiates control at a preset pv


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## TCaldwell (Jan 16, 2012)

steve, let me know the wood weight and approx makeup so as to keep test simular as possible


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## skfire (Jan 16, 2012)

WOW,
A true MEGARNTRON....or GARNOLING hybrid beast with Intelligence and Brawn.

My HUMBLE Congrats and sincere admiration!

Scott


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## bioman (Jan 16, 2012)

Why didn't garn think of that ? you pay big money for a boiler and you'd think it would run properly.


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## Como (Jan 17, 2012)

I think it is going to take me several hours to work through this.

Just a quick question, why did you use Roxul only on the front? I would have thought it would be ideal all the way around.


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## TCaldwell (Jan 17, 2012)

David, with all the bungs, cleanout ports, air collar and loading door, it didnt leave much room left, not as effective but more convenient.


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## DaBackBurner (Jan 17, 2012)

bioman said:
			
		

> Why didn't garn think of that ? you pay big money for a boiler and you'd think it would run properly.


 I wasn't going to comment I was just going to let it go, but for me some reason I can't...You pay alot of money for alot of things, and thankfully we have people that think they can improve things, so they give 'er a go. I applaud those people, their inquiring minds and am thankful for them. Without them we might as well put on a smock, grab a rock and try and kill that saber-tooth tiger. I for one am glad for the guy who invented the spear. Sorry, I didn't mean to muddle this thread up, maybe I should just go split some wood..with a hammer.


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## Como (Jan 17, 2012)

Did you use the Roxul you can get from Lowes or the specialty product for Boilers?


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## heaterman (Jan 17, 2012)

DaBackBurner said:
			
		

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In a money is no object world, Garn would be more than happy to sell you a factory made boiler like that.  Unfortunately, they have to work on this planet and within the boundaries prescribed by the people that buy them so peak technology is traded for a substantial reduction in cost.


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## Como (Jan 17, 2012)

One of the reasons I went with Garn is that it is simple by design.

I admire people who want to do this to eek out a few percentage points of extra efficiency, but from my perspective I have lots of things that can and do go wrong as it is, I would rather burn a bit more wood.


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## TCaldwell (Jan 17, 2012)

David, the big box roxul is fine.
 Da Back, You could consider me a anomalie about this stuff, it all started because i got tierd of hearing the oil boiler, and my wife and family are understanding. They all began to refer to the project as the other woman. Not suprisingly most vendors thought the project was admirable, and interesting but most unwilling to really help because of being a homeowner not with a engineering background and also not proctor&gamble;. The real truth in proving came with actually trying and watching results. Otherwise i never would have been exposed to isolation transformers, ground loops, control signals, o2, pid and on. After all this I would like to think my modifications are improvements, but in reality the gains are small with respect to money and time invested, and alot of extra liability for commercial viability as heaterman stated. With that said thankyou all for the compliments and ongoing support.


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## ewdudley (Jan 17, 2012)

TCaldwell said:
			
		

> ... but in reality the gains are small with respect to money and time invested ...



Small indeed, not counting Hack Value!

[From wikipedia:]

Hack value

Hack value is the notion used by hackers to express that something is worth doing or is interesting. This is something that hackers often feel intuitively about a problem or solution; the feeling approaches the mystical for some.

An aspect of hack value is performing feats for the sake of showing that they can be done, even if others think it is difficult. Using things in a unique way outside their intended purpose is often perceived as having hack value. Examples are using a dot matrix impact printer to produce musical notes, using a flatbed scanner to take ultra-high-resolution photographs or using an optical mouse as barcode reader.

A solution or feat has hack value if it is done in a way that has finesse, cleverness or brilliance. So creativity is an important part of the meaning.


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## heaterman (Jan 17, 2012)

TCaldwell said:
			
		

> David, the big box roxul is fine.
> Da Back, You could consider me a anomalie about this stuff, it all started because i got tierd of hearing the oil boiler, and my wife and family are understanding. They all began to refer to the project as the other woman. Not suprisingly most vendors thought the project was admirable, and interesting but most unwilling to really help because of being a homeowner not with a engineering background and also not proctor&gamble;. The real truth in proving came with actually trying and watching results. Otherwise i never would have been exposed to isolation transformers, ground loops, control signals, o2, pid and on. After all this I would like to think my modifications are improvements, but in reality the gains are small with respect to money and time invested, and alot of extra liability for commercial viability as heaterman stated. With that said thankyou all for the compliments and ongoing support.



Anomaly......I like that. Funny thing is probably 90% of the people in the US figure that any person who cuts and burns wood to heat their home is an anomaly.  We be an anomalous bunch for sure.  

I for one get quite a kick out of your project Tom. More power to ya is all I can say. What model pump did you wind up going with for the "blender".


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## heaterman (Jan 17, 2012)

ewdudley said:
			
		

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Yep! That's Tom. An anomalous hacker.   

That project has hack value that is off the charts.

*And I mean that in a most complimentary way.*


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## TCaldwell (Jan 17, 2012)

Well, i see i am not alone


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## bigburner (Jan 17, 2012)

I still would like more meat & potato's, this is a great project, the garn may not have seen a bunch of improvement, the designer built it like a carburetor and the new controls make it like fuel injection, some HP gains, better fuel economy and if he could drive up a mountain it would adjust for elevation,I am sure. My system could benefit from these control because of the amount and quality of the wood I burn. I would like to see & hear more. FYI these are my numbers from to other day one hour after reload [they need some work] O2% 15.7,CO2%5.0, CO PPM 580, Flue temp 192.2, Inlet Temp 45.5, EFF G[c] 82.4, Losses 17.6, XAIR% 301.9,CO/CO2 .0114, CO air free 2331


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## TCaldwell (Jan 17, 2012)

Bigburner, last night ran a load and checked with the testo 327 fluegas analyser,
 75lb mixed load firewood, 4 minutes from liteoff to 1200deg in secondary burn chamber, 3 minutes after that
 flue temp 277,  co12.65  ,ex air56.7  , ppm co780  , ppm coaf1224 ,  o2%7.6  ,  net eff84.7,  30 minutes later,
           ft 267     co 12.55     ex57.7     ppmco 1224   ppmcoaf 1965    o2 %7.8     net eff 84.8 

 The wood mc was a little on the high side, not sure how these numbers compare to others


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## heaterman (Jan 17, 2012)

bigburner said:
			
		

> I still would like more meat & potato's, this is a great project, the garn may not have seen a bunch of improvement, the designer built it like a carburetor and the new controls make it like fuel injection, some HP gains, better fuel economy and if he could drive up a mountain it would adjust for elevation,I am sure. My system could benefit from these control because of the amount and quality of the wood I burn. I would like to see & hear more. FYI these are my numbers from to other day one hour after reload [they need some work] O2% 15.7,CO2%5.0, CO PPM 580, Flue temp 192.2, Inlet Temp 45.5, EFF G[c] 82.4, Losses 17.6, XAIR% 301.9,CO/CO2 .0114, CO air free 2331



You talking net or gross flue temp?


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## TCaldwell (Jan 18, 2012)

Steve, what are the ranges these fluegas numbers should be in? will higher mc wood cause high ppm co?


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## heaterman (Jan 18, 2012)

For those of you who want to learn a little about combustion, here is a really good guide written by Jim Bergman, (a good lad with roots in Northern Michigan) who used to work at Testo. It's written in plain English and deals mainly with gas and oil burning equipment but much of the info is valid for solid fuel also. Pay attention to the graph of the relationship between O2, CO2, CO and excess air. Once you understand how that works you'll be able to make any burner sing a happy tune.......if you have the right equipment. 

http://www.aikencolon.com/assets/images/Testo/3161/pdfs/CombustionGuide.pdf

You can also go here    

http://www.testo.com/online/abaxx-?$part=PORTAL.USA.Applications&$event=show-from-menu&categoryid=2735668

and download the pdf field guide titled flue gas. 
That one is more technical and will make your eyes cross unless you're a chemistry/physics geek but there is some good info on solid fuel combustion in it.


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## allan (Jan 18, 2012)

Tom, nice work! I appreciated all your input when I was building my "garnlike" boiler. I also installed the tubalator in my last pass and it made a big difference. I thought about doing more to my boiler, but the truth of the matter is I like the simplicity. The other side of me wants to do what you did. It is a battle between the two sides. I have a balancing mechanism call my wallet unfortunately.


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## bpirger (Jan 18, 2012)

Tom, did you find that your mixing pump allowed you to store considerably more heat in the Garn in a firing?  I assume you can get the bottom of the tank to warmer temps.  I know my front panel sensor seems to read at least 15 degrees warmer than the water out of my supply line....a couple of hours after a burn and onward.   I assume mixing more thoroughly during the burn would allow the water at the bottom to get warmer....hence more heat in storage.

I know heaterman says the mixing is quite pronouced during the burn, and I'm sure the convection makes it so, and without sensors on the bottom of the tank I don't know what it actually does get to....but I assume an adequate mixer would really help.


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## TCaldwell (Jan 18, 2012)

aside from the old style gage i have 3 external sensors on the garn, 2 are on the front the first on the tank bottom face and the second at the tank top water line. typically right after a burn and the mix loop has shut off the 3 front sensors all read within 5deg, after say 6 hrs of load the gauge and top sensor might read 175 and the bottom sensor will read 140ish. If i start a fire within 10 minutes all will read the homoginized temp 155ish, you get the idea. the third sensor is on the actual supply pipe leaving the garn, it might read 156 before I fire. the piping for the loop is about 25ft 1.25inch bi a calefi dirt cal 2 pressure gagues a pair of isolators and a taco 0013. Suprisingly the type k thermocouple in the first section of class a  fluepipe reads about the same temp as the sensor on the supply pipe, after the fire is out.


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## Como (Jan 18, 2012)

What sort of budget are we talking about for the testing equipment?


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## TCaldwell (Jan 18, 2012)

not sure what you mean by testing equipt


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## Como (Jan 18, 2012)

You mentioned all the readings you took and what the various numbers should be, so I guess you have a gas analyzer of some sorts and I am not sure what else. Recording equipment?


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## heaterman (Jan 18, 2012)

TCaldwell said:
			
		

> Steve, what are the ranges these fluegas numbers should be in? will higher mc wood cause high ppm co?



Optimum for 20% wood is around 5-6% O2, CO2 in the 14-15% range and CO would be <100ppm. Difficult to hit optimum with wood because of all the variations in the fuel itself which present a moving target....something your setup should be able to deal with though.
 Higher MC (25%+) will produce more CO because of incomplete combustion, lower efficiency and raise the dewpoint of the flue gas. 

I just ran out to my kids place to see what numbers his 4 year old 2000 is cranking out. Long story short.....he hasn't cleaned the flues since he put it in operation.   

I checked it with the Testo 330 just for kicks anyway.
 He's getting virtually no secondary burn due to reduced air flow, the CO the thing is putting out (which you want to be careful of with wood) will kill the sensor in your 327 in about 30 seconds,  the CO2 is way low (6-7%) and the O2 is way high 13-14%. Flue temp at the outlet is running about 320 and it should be lower by about 30-50*. Efficiency though is still running 74% which is a testimony to the extraordinary heat transfer a Garn is capable of.
 Needless to say, we have an appointment with a couple of brushes this weekend...........
His wood is mostly red oak which was cut into 8 foot lengths 2 years ago and made into firewood this spring. It still hits 20-25% MC in the middle of a fresh split.


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## heaterman (Jan 18, 2012)

Como said:
			
		

> What sort of budget are we talking about for the testing equipment?



Budget!!?? Weee don neeed no steeenking budget!!


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## Como (Jan 18, 2012)

Well the Testo is $1700, so that is not on my shopping list.


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## Tonttu (Jan 18, 2012)

Wow...this is really impressive and way above this simple wood gnome's understanding right now, but the links to the charts and to the combustion theory literature that have been provided will make for some interesting reading for the cold winter nights ahead.
For the simple layman (as I am), how does the efficiency for your setup compare to the basic Garn controller system, and to the Garn digital controller system?


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## bigburner (Jan 18, 2012)

Heaterman -"You talking net or gross flue temp?"  The NETT is 146.5


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## Sawyer (Jan 18, 2012)

heaterman said:
			
		

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I cleaned my Garn after one year of continuous operation and found very little residue, maybe 2 cups + what blew out the flue when the motor started. My temps at the fan are still hitting 500-550* at peak weather I am burning 20% hard maple or 15% pine. Is this cause for concern? Did I not do a good job of cleaning and heat transfer is hindered? I will also try to get a temperature reading at the outlet.


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## heaterman (Jan 18, 2012)

Sawyer said:
			
		

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Peak temp will vary not only based on MC but also load volume and density. Try varying how much wood you stack in it and also location front to back. 500 range for a peak temp would not be considered abnormal. You would expect to see that for maybe 15-20 minutes before beginning to drop. 
As for the cleaning issue, I would dare say you did a fine job. I think my son's problem is letting ash build up in front of the lower air inlet to the point that some fell into the air collar and is restricting air flow there.


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## Sawyer (Jan 18, 2012)

Thanks Steve, I have been getting these temperatures with any 3/4 to full loads. I just checked moisture and the last load's moisture content was 15%. Perhaps it help if I put a half brick approximately 4"  in front of the air inlet to slow the burn. I do split 6"-8" logs once as it seems the "rollers" never seem to want to dry easily. I will also check to see how long the 500+ flue is maintained before dropping.


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## bpirger (Jan 18, 2012)

George....I've been getting up into the 500-550 range as well...wondering the same thing.  Burning mostly cherry and ash...cut and split since this past early Spring.  I wonder the same thing....I guess I need to measure my actual outlet temperature.  

But I have been filling more than 3/4 typically....pretty much filled.

I think for next year I'm going to cut a whole bunch of cookies and set one of those in front of the pile, to help deflect some of the primary air from the bottom upward....and then it will burn right up.  I'll use a small cut off chunk now if I have one...and it seems like it does help it burn cleaner...


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## Sawyer (Jan 18, 2012)

Good idea Bruce. I can throw a couple of logs on the sawmill and cut them into hardwood 2x4's, sticker, and by mid summer they will be dry. I could cut a couple of logs worth for you if you care to drive on over and pick them up. ;-)


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## TCaldwell (Jan 19, 2012)

tonttu, 
 If you go back on this thread you will see a link to two graphs, one represents a stock garn and the other with o2 control. the stock graph represents a a typical burn trend of a low o2 level for a period of time and slowly escalates till end of burn, due to the combustor and air delivery system the garn handles this efficiently with no smoke, that hot fast burn is the garn's trademark. My opinion is that maintaining a relatively static o2% throughout the burn is more efficient. There would be several criteria monitored  for many burns needed to actually determine if one approach is better than the other, other than trading some flue analyser numbers for comparison, it was a fun project.


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## Sawyer (Jan 19, 2012)

Tom, what part does your tabulator play in this formula? Significant? What model did you buy?


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## heaterman (Jan 19, 2012)

Just for everyone's info, Garn is now using a turbulator/flow straightener/diffuser or whatever you want to call it in the current units. It is a V shaped piece of metal about 3' long that lays on it's side in the last pass of the heat exchnager right after the combustion blower. I believe it will retrofit in all Garns of recent manufacture.


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## Sawyer (Jan 19, 2012)

It appears that the forum members are not the only ones benefiting from forum discussions. ;-)


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## bpirger (Jan 20, 2012)

Yeah, that's what I was wondering....If we are all seeing 450-550 on the flue temp, maybe we should have a little turbulator of some sort in there to scrub a little more heat.  LIke a nice piece of steel 4" wide, heated and twisted, and about 3-4' long.  It could be removed from the HX tube when cleaning right from the front.....


SO we can buy this for Garn?


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## Sawyer (Jan 20, 2012)

Shouldn't be difficult or expensive to have one made if one had a fabricator nearby or equipment to do it yourself.

I have neither. :-(


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## heaterman (Jan 20, 2012)

Sawyer said:
			
		

> Shouldn't be difficult or expensive to have one made if one had a fabricator nearby or equipment to do it yourself.
> 
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There's more to it than just a piece of metal in the flue. Martin went through more than a few designs until he found one that did what he wanted it to.

Not saying that this or that might not show an improvement but you have to know what your looking for before you can shoot at it.


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## Frozen Canuck (Jan 20, 2012)

+1 on having a plan before you begin. It did occur to me that you could do this "too good" a drive the unit into the condensing range & that would be a very bad & messy thing.
Not saying "don't try" just encouraging a thought through plan first. I like & appreciate all the tinkering many of you do, just be a tinker with a plan is all. 
Good luck in your efforts of achieving 87.9999% eff. Hope you don't get to 88% or beyond.


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## Sawyer (Jan 20, 2012)

heaterman said:
			
		

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Understood Steve, perhaps smoking or gambling would be an easier compulsion to control.


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## heaterman (Jan 20, 2012)

Sawyer said:
			
		

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LOL

  Whoda' thunk that wringing the last bit of efficiency out of a wood burner could be so addictive.

I think the key to an effective turbulator would be achieving turbulent rather than laminar air flow characteristics in the flue tubes. As far as the Garn is concerned I think that there are a couple reasons that the baffle is after the combustion fan rather than before.


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## bpirger (Jan 21, 2012)

According to Keith at Garn, $44 for the piece.  I have asked if there is an average exit flue gas temp drop....I'll pass along what I hear.  It is soon to reach the Parts section of the website.


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## Sawyer (Jan 21, 2012)

Thanks for checking!

-22 degrees, Garn cruising with a 400 degree flue temp.


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## Jim K in PA (Jan 24, 2012)

Hey Tom - just got back to Hearth after a while and am catching up.  Glad to see you got everything up and running.  I was hoping you would call me to come up and help with the setup after your move!  I see the "skunkworks" is in full operation.  Great job.

After a while you get a feel for when the GARN gets "up on plane" so to speak.  I know it's gassifying within 5 minutes based on the flue temp and the change in sound of the exhaust.  Nice to see some empirical data confirming what I "feel".


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## TCaldwell (Jan 24, 2012)

Hi Jim, 
 I ended up doing the plumbing in stages, mostly after work also I barely fit behind the garn where most of the plumbing is located. I was thinking about the offer but realized it became a one small person job, thanks anyway. The major time consumer became the controller parameter set-up. I would do a burn, datalog and email file to cybosoft, they would evaluate trend and email parameter updates to load into controller for a new burn. All the wood was weighed to 60 lb for initial testing, and varied there after, some nights I got 2 burns in, others just one, this went on for about 6 weeks. At this point I am very satisfied with the controller performance and results, some latest combustion data,
 o2=6.6%
 excess air=45.1%
 co2=13.7%
ppm co=320
ppm coaf=468
eff=86.4%
sec burn temp=1580degf
flue temp=264.2degf
 with my set-up these results are relatively consistent throughout the burn and repeatable from one burn to the next.


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## Jim K in PA (Jan 25, 2012)

So now the question is . . . what will you tinker with next?


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## TCaldwell (Jan 25, 2012)

Well Jim, you know this is a addictive lifestyle! I actually have lot's to catch-up on, insulating pipes, getting ahead on wood ect.
tom


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## TCaldwell (Jan 25, 2012)

Jim, you know this 'hobby' is an addictive lifestyle! I actually have alot to catch-up on, insulating pipes, catching up on wood ect.
 thanks
tom
            sorry for the double post


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