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.