Weird woodstove behavior

[Scooby074]

Not my stove, but a video i came across.

Anybody ever see a stove "explode" (sorry for the term), like it built backpressure then blows the lid? Smoke puffing out the seams too. Very weird behavior,

This guy has been having issues for a while. There are other videos posted of unusual behavior. Says the stack's clean. Ive never seen anything like it.

[ame=http://www.youtube.com/watch?v=UGE2xE6oHzc]2012 Mar 03 - Harmon stove goes BOOM again - YouTube[/ame]

 

[Egon]

Incomplete combustion, flamable gases collect and finally ignite.

Might be caused by poor draft.

 

[westcliffe01]

This stove has a "ceramic package" in the rear of the stove which is intended to burn off hydrocarbons and soot in the flue gas. Not sure if they called the method an "Updraft" combustor or not. It is not a catalytic system, and several other manufacturers tried a similar system (Vermont Castings notably). None were successful and there were many many frustrated customers since these stoves all cost around $2500 before installation.

The problem is that one has to burn the stove in "bypass" mode until the stove has heated up and one has a good coal bed to keep the "updraft" system "lit off". Then the bypass is closed and the pre-heated afterburner cleans up the emissions as well as produces a substantial amount of the heat given off by the stove. However operation of the ceramic uncatalysed combustor has proven to be extremely finicky and the ceramic system itself is easily damaged and fragile. Replacing the ceramic package can run over $400 + labor and the manufacturers appear to have been rejecting any and all claims for warranty repairs.

If the combustion in the ceramic part "stalls" as it has been described, then it quickly cools down and ceases to function. Then combustible gases collect in the firebox where there is insufficient oxygen until enough oxygen accumulates when it then ignites in a "thump". Not an explosion, but rapid combustion which generates some overpressure which is why you see some smoke enter the room. Yes, it is very irritating and ultimately the smoke will contaminate anything in the room. And the heat output is greatly reduced too.

Lots of unhappy people. Buyer beware...

 

[deerefan]

This stove has a "ceramic package" in the rear of the stove which is intended to burn off hydrocarbons and soot in the flue gas. Not sure if they called the method an "Updraft" combustor or not. It is not a catalytic system, and several other manufacturers tried a similar system (Vermont Castings notably). None were successful and there were many many frustrated customers since these stoves all cost around $2500 before installation.

The problem is that one has to burn the stove in "bypass" mode until the stove has heated up and one has a good coal bed to keep the "updraft" system "lit off". Then the bypass is closed and the pre-heated afterburner cleans up the emissions as well as produces a substantial amount of the heat given off by the stove. However operation of the ceramic uncatalysed combustor has proven to be extremely finicky and the ceramic system itself is easily damaged and fragile. Replacing the ceramic package can run over $400 + labor and the manufacturers appear to have been rejecting any and all claims for warranty repairs.

If the combustion in the ceramic part "stalls" as it has been described, then it quickly cools down and ceases to function. Then combustible gases collect in the firebox where there is insufficient oxygen until enough oxygen accumulates when it then ignites in a "thump". Not an explosion, but rapid combustion which generates some overpressure which is why you see some smoke enter the room. Yes, it is very irritating and ultimately the smoke will contaminate anything in the room. And the heat output is greatly reduced too.

Lots of unhappy people. Buyer beware...

Reminds me of a flashover in a house fire. I would remove it from my house quickly.

 

[radioman]

I have a vermont casting stove and it does same with mine. It burns too slow when restarting fire on coals. I found that its due to very airtight house. IF I see smoke coming thru the stove, I just open the door to garage and it reverses the smoke. I dealt with this for nearly 10 years and then got my furnace and hot water tank replaced and had energy audit done before and after replacement.

This is what I learned- with both bathrooms fans running upstairs, it pulls air from the gas hot water tank flue as per energy audit before replacement of tank and furnace. With the new high efficiency water tank installed and high efficiency gas furnace with their own air intake, I have NO more backdrafting smoke coming back in my house from the woodstove.

 

[bironacad]

Egon is right here is the long version, lol.

They use to make gas by baking coal. It was called manufactured gas and was used for gas lighting late nineteenth century. The air tight stove when banked down can actually bake the wood instead of burning it producing creosote and distilling out gas. The lack of air for combustion momentarily extinguishes the flame the residual heat bakes out the gas from the creosote, air slowly creeps in until there is enough for combustion and ignites the baked gas and poof.

He needs to burn the stove with more air. New construction and tight homes limits the need for heat and people try to run the stoves below their minimum firing rates.

What is creosote? By definition it is a combustible deposit that originates as condensed wood smoke, including tar, vapors, and other organic compounds.

Check out coal gas.

HowStuffWorks "Natural Gas"

I know more then you wanted eh

 

[Scooby074]

Great info guys.

Westcliffe, interesting about the ceramic package. I wonder if that's the source or if hes not running the stove correctly? I think he mentioned in a reply that it only happens when the damper is closed. Not sure if he meant stove damper or pipe damper? He shouldnt be using a pipe damper anyways.

He says that it was a WETT certified install, but to me the black pipe looks to be installed wrong (crimped end up). This calls into question whether is truly was installed by a WETT contractor.

He also says its in a R2000 home (very air tight) but that it has external make up air.. so i cant imagine it starving for combustion air or backdrafting?

Latest is that the dealer says its caused by "temperature inversion" and is getting him to install a swivel draft cap to help the draft.

All i know is i wouldnt be using it in my house. Seems like a huge potential for CO poisoning.

[ame=http://www.youtube.com/watch?v=ibeQsoiK58c]Smoking pipe, Harman Oakwood Fireplace. - YouTube[/ame]

 

[rambler]

I agree with the others. It's building up combustable gasses, and eventually they hit the right O2/ gas combination and go poof. Not enough air, poor design, too short chimney, etc.

--->Paul

 

[westcliffe01]

When they introduced this type of stove a few years ago, the manufacturers made outrageous claims which the product couldn't live up to. I read of users complaining about their stoves for the next 3 years on hearth.com, so I know for a fact that the ceramic combustor, which is meant to cleanly burn just such vapors was a failed concept. If that stove had a catalyzed converter, there would be no problem whatsoever with it functioning in those type of burn conditions. But in the absence of a catalytic coating the temperature that has to be maintained in the combustor is at least 400F higher which is why it is so unreliable.

The damper is a part integral to the stove. Since the flue gasses don't want to flow down before they leave the stove (particularly when the stove and flue are cold) one opens the damper and the smoke can leave the stove at the top of the combustion chamber. Once everything is warmed up and the fire is cranking, the bypass is closed and the flue gasses flow through the ceramic combustor.

See below for the item of interest

 

[Scooby074]

sounds to me like this combustor wouldnt like it when the stove is near the end of the burn, ie: low stack temps. Or even low temps caused by wet wood. Doesnt sound like a very good system. Glad i didnt go with one of the high tech stoves when i put mine in.

 

[westcliffe01]

The hydrocarbon vapors occur in the first 1/3 of the burn. After that it is just carbon burning to produce CO and CO2. So the latter part of the burn only matters in that you do not want a CO producing device in your home. If there is enough air flow, you will be getting CO2.

For northerly lattitudes there is little that can beat a proper catalytic stove like the Blaze King. Particularly when you have only softwood with a lot of resin content.

 

[Scooby074]

Ive read good things on the Blaze king, particularly that it produces lots of heat... But i wonder if the catalitic converters and other high tech add ons are overcomplicating what should be a simple woodstove?

Im likely going to upgrade next year, and im looking at models. Currently im leaning towards the Jotul F600, but i kinda wont something top load which the Jotul doesnt have.

 

[westcliffe01]

Catalytic stoves have the highest efficiency, best reliability, longest burn times and they save your back. Seriously, compared to an old "airtight" stove, you could easily halve your firewood consumption with a Blaze King. And have a LOT less work to do.

 

[clemsonfor]

Think they call it back puffing.

It will ignite and then blow out?

I get them everynow and then on my insert on a low burn damped way down. I have a cat model as well, it being an isert though i never get smoke in the house, if it do happen when the stove does it. It rarely happens a real big one a few times a season maybe.

 

[clemsonfor]

I have a 3.5 cuft firebox Highvalley wood stove. it has catalysts in it. I would not go other way. if i had the cash i would go blaze king king all the way. Get 40+ hr cruise burns on a load of wood. Mine will go 24+ on a low burn in shoulder temps. But usually bursn 10-12 hours on a full load and if your really racing it you will get mega heat on 8 hr loads.

I would not own a non catalyst stove. YOU MUST have DRY SEASONED wood.

 

[Scooby074]

I have a 3.5 cuft firebox Highvalley wood stove. it has catalysts in it. I would not go other way. if i had the cash i would go blaze king king all the way. Get 40+ hr cruise burns on a load of wood. Mine will go 24+ on a low burn in shoulder temps. But usually bursn 10-12 hours on a full load and if your really racing it you will get mega heat on 8 hr loads.

I would not own a non catalyst stove. YOU MUST have DRY SEASONED wood.

Those burn times seem incredible. I get overnight (8 hr) on a full load, damped down to say 25%

Are you saying that Dry wood is required for the cat stoves? Or can you get away with damp wood? That could make a difference to me as my wood is typically 1yr old, so not the driest.

 

[clemsonfor]

Those burn times seem incredible. I get overnight (8 hr) on a full load, damped down to say 25%

Are you saying that Dry wood is required for the cat stoves? Or can you get away with damp wood? That could make a difference to me as my wood is typically 1yr old, so not the driest.

If your burning 1 yr old aspen elm ash or any pine species your fine. Those of yall north of say virginia or illinois say oak takes 3 yrs to dry. Im burning some that was cut in july 2011. Its say 25% moisture content which is borderline of burable in a cat stove per advice andthe manual. Im only able to get away with it as SC was like a kiln this last summer. Dry burns way better and can be damped down faster and get longer burntimes because of it as well as more heat.

NO you dont want wet wood or green in anyway, if you get to much steam on a hot CAT you can crack it from the moisture, or just plug it up eary with all the wet smoke you put out. The cats are in the $100 to $200 dollar range depending upon size. I have 2 in my stove and think there right aroung $90 a piece, i dont want to gunk them up, im hoping they last the 4-5 yrs they say you can get out of them.

I can burn 24/7 easy loading once around say 6pm ish or earlier or bit later and then once in the am when i get up round 6:30-7am before work. When i get home i have about a 1-2 gallon bucket full of HOT coals that easily start the next load. This keeps about 2000 of my 2500sqft home warm down to days in the highs of 40s easy no other heat. For you this does not seem cold i know, but i have nothing but r19 attic insulation in my home so its not the best insulated home. I do have new efficient windows and doors though.

 

[forgeblast]

Seeing the smoke come back is similar to what was happening with my stove, but my issue was the chimney was too short and I would have back pressure coming off my roof forcing the smoke back down into the house.
We went with an lp stove up stairs, looks like a wood burner but with remote control and has thermo, and put the wood stove in the basement, and had the chimney from the basement cleaned and extended.

 

[MotorSeven]

I agree with the others. It's building up combustable gasses, and eventually they hit the right O2/ gas combination and go poof. Not enough air, poor design, too short chimney, etc.

--->Paul

Agreed. I think it might be a candidate for an OAK system...Outside Air Kit.


You guys with Cat's when you say a 10-12 hr burn, are we talking a hot bed of coals? My vintage('86) Hearthstone will do that every night but the beast can hold 6- 24" splits of wood. 24 hr burn...no way, not with my stove.

 

[Oaktree]

I have the same stove, and mine will occasionally do that as well, though as others have noted it's usually when I turn the air down too soon. 99% of the time it's just fine. Considering my house is 180 years old, I don't think "too airtight" is anything I have to worry about!
I'd wondered what caused this...I'd only ever seen back puffing before when it was windy.

If your burning 1 yr old aspen elm ash or any pine species your fine. Those of yall north of say virginia or illinois say oak takes 3 yrs to dry. Im burning some that was cut in july 2011.

Pine? Ugh, I only use that for kindling. Aspen's not much better IMHO.
While I think 3 years is a bit overkill, I always cut one year ahead....6 months drying isn't enough.