Yes, your stove is over drafting... Blame the ...

[sadpanda]

A basic heat reclaimer can reduce draft, at the expense of dramatically increasing creosote accumulation. They are also butt ugly and noisy. The reclaimer that sadpanda describes is not too far from what MF Fire was testing, but with the upper thermocouple in the room IIRC. It's a costly setup.

I'm for any and ALL possible solutions...

The best most fool proof solution is the one with zero user intervention. Honestly given the 'variability' monster, every tool available should be fair game if the system is calibrated and validated.

Step 1 should be a simple draft evaluation, pipe diameter should be specified based on this calc. If that means 4in pipe on a 6in collar, so be it.

Step 2 stoves should have a barometric control to adjust for seasonal / burn cycle variance. A simple mechanical bimetallic spring can disable it if flue temps are too low and air can be pulled from the back side/top of the stove so its pre-heated.

Key damper and the rest should be available but avoided... How many times have you/wifey/spawn/newb forgotten to open the key damper(s?) before opening the door?

re: creosote forming on reclaimers... So what? If we are using dry wood, there should be no creosote and if we turn the stove down too far, the magic EPA honeycomb thingy is there to burn all the bad stuff away right? so again no problem. Even still, if creosote is likely to form anywhere it will be in the reclaimer tubes... Which normally have scrapers etc. If the reclaimer is emptied every load, whats the issue? What about building the reclaimer function into the stove? Aside from trying to simultaneously burn all of the hydrocarbons AND shoot them out the cap before they can condense, we don't need 600F air in the flue to generate sufficient draft (according to meaningless maths), so why not send it through some more steel/surface area and cool it off?

re: snorkeling the intake... I'm still waiting for the list perils and certain death

 

[sadpanda]

Heat reclaimers above a modern wood burner work very well in the wood furnace world. They call them heat exchangers but the exhaust from the firebox is routed through a back and forth series of small pipes within a blower box prior to leaving the appliance. Often, these things run output flue temperatures below 200 as measured with a flue probe! Minimal electronics prevent overcooling the exhaust, rather, they measure plenum temperatures and vary the blower speed.

Above a woodstove designed to strip as much heat as possible from the flue gasses to be efficient, I would not add a heat reclaimer.

You posted while I was tapping on a phone.

But they are illegal yes?

 

[bholler]

I'm for any and ALL possible solutions...

The best most fool proof solution is the one with zero user intervention. Honestly given the 'variability' monster, every tool available should be fair game if the system is calibrated and validated.

Step 1 should be a simple draft evaluation, pipe diameter should be specified based on this calc. If that means 4in pipe on a 6in collar, so be it.

Step 2 stoves should have a barometric control to adjust for seasonal / burn cycle variance. A simple mechanical bimetallic spring can disable it if flue temps are too low and air can be pulled from the back side/top of the stove so its pre-heated.

Key damper and the rest should be available but avoided... How many times have you/wifey/spawn/newb forgotten to open the key damper(s?) before opening the door?

re: creosote forming on reclaimers... So what? If we are using dry wood, there should be no creosote and if we turn the stove down too far, the magic EPA honeycomb thingy is there to burn all the bad stuff away right? so again no problem. Even still, if creosote is likely to form anywhere it will be in the reclaimer tubes... Which normally have scrapers etc. If the reclaimer is emptied every load, whats the issue? What about building the reclaimer function into the stove? Aside from trying to simultaneously burn all of the hydrocarbons AND shoot them out the cap before they can condense, we don't need 600F air in the flue to generate sufficient draft (according to meaningless maths), so why not send it through some more steel/surface area and cool it off?

re: snorkeling the intake... I'm still waiting for the list perils and certain death

Do you really think dry wood means no creosote can accumulate???

And I told you exactly why you can't "snorkel " the air intake

 

[bholler]

You posted while I was tapping on a phone.

But they are illegal yes?

They are not allowed to be used on a ul listed appliance as it should be they are horrible creosote making devices.

 

[john26]

Key damper and the rest should be available but avoided... How many times have you/wifey/spawn/newb forgotten to open the key damper(s?) before opening the door?

Not much different than a cat bypass or bypass that Lopi uses

 

[bholler]

I'm for any and ALL possible solutions...

The best most fool proof solution is the one with zero user intervention. Honestly given the 'variability' monster, every tool available should be fair game if the system is calibrated and validated.

Step 1 should be a simple draft evaluation, pipe diameter should be specified based on this calc. If that means 4in pipe on a 6in collar, so be it.

Step 2 stoves should have a barometric control to adjust for seasonal / burn cycle variance. A simple mechanical bimetallic spring can disable it if flue temps are too low and air can be pulled from the back side/top of the stove so its pre-heated.

Key damper and the rest should be available but avoided... How many times have you/wifey/spawn/newb forgotten to open the key damper(s?) before opening the door?

re: creosote forming on reclaimers... So what? If we are using dry wood, there should be no creosote and if we turn the stove down too far, the magic EPA honeycomb thingy is there to burn all the bad stuff away right? so again no problem. Even still, if creosote is likely to form anywhere it will be in the reclaimer tubes... Which normally have scrapers etc. If the reclaimer is emptied every load, whats the issue? What about building the reclaimer function into the stove? Aside from trying to simultaneously burn all of the hydrocarbons AND shoot them out the cap before they can condense, we don't need 600F air in the flue to generate sufficient draft (according to meaningless maths), so why not send it through some more steel/surface area and cool it off?

re: snorkeling the intake... I'm still waiting for the list perils and certain death

A 4" pipe on a 6" stove will not have enough volume on startup and will smoke back into the house. Draft measurement is only one part of the equation. You also have to have the correct volume.

Why should key dampers be avoided??? If you are using it to bring draft into spec you would not have smoke spillage at all when you open the door.

Also the "magic EPA honeycomb thing" only works.
1 if there is one which many stoves don't have one.
2 if there is enough temp to keep that cat active.

 

[sadpanda]

I am not bring snarky at all. I am simply telling you that your calculations don't take into account many many variables we deal with every day in the field that can drastically effect the actual measured draft. I would love it if there was a simple formula that could tell us accurately what the draft in a given chimney will be. But there simply is not.

I know what you are saying. And if an appliances output temp was high enough it may work. But most modern stoves do not have high enough output temps to be able to pull extra heat off of the stack and stay above the condensation point. You are also talking about adding a massive amount of electronics to woodstoves when a simple manually controlled key damper almost always works perfectly fine.

An elevated air intake can and has acted as a second chimney sucking flue gasses out of the stove through the intake pipe causing a fire.

This is no longer allowed because of problems that arose which is how many codes come about.

Ah there it is. Again I'm behind the posts. Secondary chimney yes.

If only there was a way to figure out the likelyhood of this happening... Perhaps something with numbers.

Without significant intervention, my flue will happily pull 1.5" with the stove turned down and peg my gauge at 2.5"+ and spike 2000F flue temps if I followed @BKVP reload instructions and opened the taps on a fresh reload.

Using my basic math, assuming the intake is in fact routed outside, even something silly like a 15ft pipe would only pull .02" @25 cfm. That's obviously not factoring 'variables' like wind shear but it illustrates my point... Just like adding an evil key damper or heat exchanger, its not instant death. Its all against the law anyway

 

[bholler]

Ah there it is. Again I'm behind the posts. Secondary chimney yes.

If only there was a way to figure out the likelyhood of this happening... Perhaps something with numbers.

Without significant intervention, my flue will happily pull 1.5" with the stove turned down and peg my gauge at 2.5"+ and spike 2000F flue temps if I followed @BKVP reload instructions and opened the taps on a fresh reload.

Using my basic math, assuming the intake is in fact routed outside, even something silly like a 15ft pipe would only pull .02" @25 cfm. That's obviously not factoring 'variables' like wind shear but it illustrates my point... Just like adding an evil key damper or heat exchanger, its not instant death. Its all against the law anyway

Ok you can run what ever numbers you want but the fact is that it is not allowed because doing so has caused to many house fires and they determined it was unsafe.

Again your numbers don't take into account the thousands of variables that go into this. And actual real world experience tells us elevating the air intake carries to much risk.

So only things that cause instant death every time should be against code? What about possible death say 50% of the time? 10%? 5%? 1%?

I know as a professional if one of my installs cause a death I couldn't live with myself. Even without death the loss of a house is not something I am willing to risk for my customers.

 

[BKVP]

You posted while I was tapping on a phone.

But they are illegal yes?

Good question. Around 8 years ago a state regulator was complaining to me and an EPA staff person about the amount of smoke that was coming from the outdoor wood heater (OWH) next to their home. The state regulator said he had spoke with his neighbor about the problem. The owner of the OWH said "Pound sand, this is exempt!" Fast forward to 2015's new rule. First, EPA can now delegate the authority of enforcement to state and local authorities. Check that box! Second, the 2015 does not have any exempt products. Before any of you say what about cook stoves or masonry heaters or blah, blah, blah, each of those products is now defined within the rule. Prior rules did not define what constituted a wood burning fireplace etc.

Now the rule also states it is illegal to install or operate a covered product (not products with set max emissions levels) but covered (meaning mentioned in the rule) other than as tested or described in the Owners & Operators Manual. So you can take that for what you want.

Heat reclaimers and there are many types on the market still to this day, played a role in the past or with inefficient wood burning products. However, most wood heaters being manufactured today are vastly cleaner and vastly more efficient. Speaking strictly for our company, we do not endorse their use on our products.

 

[BKVP]

A 4" pipe on a 6" stove will not have enough volume on startup and will smoke back into the house. Draft measurement is only one part of the equation. You also have to have the correct volume.

Why should key dampers be avoided??? If you are using it to bring draft into spec you would not have smoke spillage at all when you open the door.

Also the "magic EPA honeycomb thing" only works.
1 if there is one which many stoves don't have one.
2 if there is enough temp to keep that cat active.

Not temp...gases.

 

[bholler]

Not temp...gases.

But it needs heat as well doesn't it? I know if I turn mine down to low there are still plenty of gasses but the cat stalls.

 

[SpaceBus]

A basic heat reclaimer can reduce draft, at the expense of dramatically increasing creosote accumulation. They are also butt ugly and noisy. The reclaimer that sadpanda describes is not too far from what MF Fire was testing, but with the upper thermocouple in the room IIRC. It's a costly setup.

Did MF Fire bring a product to market? I thought they were the ones building the boxy SBR stoves.

 

[SpaceBus]

Good question. Around 8 years ago a state regulator was complaining to me and an EPA staff person about the amount of smoke that was coming from the outdoor wood heater (OWH) next to their home. The state regulator said he had spoke with his neighbor about the problem. The owner of the OWH said "Pound sand, this is exempt!" Fast forward to 2015's new rule. First, EPA can now delegate the authority of enforcement to state and local authorities. Check that box! Second, the 2015 does not have any exempt products. Before any of you say what about cook stoves or masonry heaters or blah, blah, blah, each of those products is now defined within the rule. Prior rules did not define what constituted a wood burning fireplace etc.

Now the rule also states it is illegal to install or operate a covered product (not products with set max emissions levels) but covered (meaning mentioned in the rule) other than as tested or described in the Owners & Operators Manual. So you can take that for what you want.

Heat reclaimers and there are many types on the market still to this day, played a role in the past or with inefficient wood burning products. However, most wood heaters being manufactured today are vastly cleaner and vastly more efficient. Speaking strictly for our company, we do not endorse their use on our products.

Will site built masonry "stoves" be regulated moving forward? Seems like a relatively miniscule market to watch. It also sound like you are saying there will be regulation on wood cookstoves as well. I haven't read any of the legislation so I've been under the impression that cookers and masonry heaters/stoves were indeed unregulated.

 

[begreen]

Did MF Fire bring a product to market? I thought they were the ones building the boxy SBR stoves.

Yes, but it is different from the test model they demonstrated at the Green Heat decathlon several years ago in DC. They have a couple of stoves out, the Catalyst and the Nova. The Catalyst is what evolved from the contest. It has 3 thermocouples feeding a processor. They measure stove temp, cat temp and room temp. It has a combustion fan governed by a smart controller, that apparently regulates the air supply too. Cat engagement appears to be manual. The Nova is a single burn-rate stove. We've only seen a couple reports from owners so far, but they have been favorable.

 

[SpaceBus]

Yes, but it is different from the test model they demonstrated at the Green Heat decathlon several years ago in DC. They have a couple of stoves out, the Catalyst and the Nova. The Catalyst is what evolved from the contest. It has 3 thermocouples feeding a processor. They measure stove temp, cat temp and room temp. It has a combustion fan governed by a smart controller, that apparently regulates the air supply too. Cat engagement appears to be manual. The Nova is a single burn-rate stove. We've only seen a couple reports from owners so far, but they have been favorable.

It really sounds like a pretty good system. It's a shame they had to put the tech in such a homely package.

 

[begreen]

It really sounds like a pretty good system. It's a shame they had to put the tech in such a homely package.

Yes, they did a lot better with the Nova on the looks end.

 

[SpaceBus]

Yes, they did a lot better with the Nova on the looks end.

There's also something about the website that makes it all look like a scam or "as seen on TV" type product as well. It does seem like the kind of stove I would put in my MIL's house and trust it not to burn the house down, assuming it all works properly.

 

[begreen]

There's also something about the website that makes it all look like a scam or "as seen on TV" type product as well. It does seem like the kind of stove I would put in my MIL's house and trust it not to burn the house down, assuming it all works properly.

They started the business straight out of college. It's a small enterprise, but the stoves are not cheaply made. I'd love to try both out just to expand my burning knowledge. They are interesting engineering designs.

 

[john26]

MFfire say burn time up to 12 hours I would imagine if the draft fan ran much it would greatly decrease burn times. The draft inducing fan on the chimney instead of the air intake looks a lot like how high efficiency gas furnaces are designed. I wonder if the control kicks the draft blower on if the cat falls below a set temp even if the room thermostat is satisfied?
My idea is a thermocouple on the cat feeding back to a small PLC with a 4-20 milliamp out put controlling an electrically actuated damper that would control air to the intake with out a draft blower that would be more efficient. If a PLC was used a digital manometer could be installed to control an automated flu damper. And Or programming could be used to open the flue damper if the flu temp drops below a set point. A variable speed blower motor could be added as well to maintain temps in the air jacket as well or possibly even thermostat controlled for room comfort. Now that being said that is a lot of stuff for a wood stove and would be very pricey it would be better suited for a wood furnace.

 

[begreen]

I think the combustion blower is just for startup. The objective being to get smoke free asap. The convection blower is variable speed and can also be controlled by the remote app.

 

[john26]

I think the combustion blower is just for startup. The objective being to get smoke free asap.

you are probably right I could not find it in the manual or on there web site but i did find this on page 33 of the manual
“Boost Mode Activated” – If your fire is dying Catalyst will go into
boost mode, speeding up your combustion fan to deliver essential air
to the fire. Boost mode is commonly occurs after start-up at the
beginning of a cold burn or as the wood runs out and your fire dies.

 

[begreen]

you are probably right I could not find it in the manual or on there web site but i did find this on page 33 of the manual
“Boost Mode Activated” – If your fire is dying Catalyst will go into
boost mode, speeding up your combustion fan to deliver essential air
to the fire. Boost mode is commonly occurs after start-up at the
beginning of a cold burn or as the wood runs out and your fire dies.

The combustion blower is variable speed. During the 5 minute start up mode it is at high speed.

 

[BKVP]

But it needs heat as well doesn't it? I know if I turn mine down to low there are still plenty of gasses but the cat stalls.

There are fewer than 2 stoves that can run as low as ours in kg/h and produce as low emissions. Can we work on your stove...perhaps swap out the cat? It should not stall in low burn rates. Is your stack 15' +.....let's not consume this thread, just give me a call. 509-522-2730.

 

[BKVP]

Will site built masonry "stoves" be regulated moving forward? Seems like a relatively miniscule market to watch. It also sound like you are saying there will be regulation on wood cookstoves as well. I haven't read any of the legislation so I've been under the impression that cookers and masonry heaters/stoves were indeed unregulated.

So interestingly, the masonry heater council voted to litigate against the EPA. They want to be a regulated product so that they can be included in many incentive programs. Subsequently, they have dropped their case...as I recall. It's really tough to set up, site (lab) your heater and then test and remove. Great group of manufacturers that want to be recognized for stove change outs, tax credits etc.

 

[BKVP]

MFfire say burn time up to 12 hours I would imagine if the draft fan ran much it would greatly decrease burn times. The draft inducing fan on the chimney instead of the air intake looks a lot like how high efficiency gas furnaces are designed. I wonder if the control kicks the draft blower on if the cat falls below a set temp even if the room thermostat is satisfied?
My idea is a thermocouple on the cat feeding back to a small PLC with a 4-20 milliamp out put controlling an electrically actuated damper that would control air to the intake with out a draft blower that would be more efficient. If a PLC was used a digital manometer could be installed to control an automated flu damper. And Or programming could be used to open the flue damper if the flu temp drops below a set point. A variable speed blower motor could be added as well to maintain temps in the air jacket as well or possibly even thermostat controlled for room comfort. Now that being said that is a lot of stuff for a wood stove and would be very pricey it would be better suited for a wood furnace.

I know a certain stove manufacturer/nerd that designed a stove that had 3 tiered cats, multi O2 sensors, 3 different fan systems for air introduction etc. Emissions were nearly zero. One day an EPA random compliance audit took place at the factory. The guy shared the prototype with the inspector.

When asked. "what's keeping you from bring it to market?" my friend said 2 things. First the cost. It would retail at $20-$30k. Second, his research showed 97% or more wood burners preferred low tech for minimal technical issues. He is still a dear friend and has not shelved the project!! I've seen the stove...it has a future.