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Huffing woodstove

Started by Handy Andy, November 28, 2011, 08:56:39 AM

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Handy Andy

  Bought a new non-catalytic Vermont castings defiant 2 years ago.  Last year, was having trouble with huffing, assumed it was because my wood wasn't dry enough.  So this year, I cut and split my wood last winter.  We had a horrible drought this summer, with temps up to about 115 degrees, and the wood I cut up was from degraded logs, not fresh.  It seems really dry. Put it in the basement, and put the dehumidifier next to it.  Vacuumed out the stove, took the top off, vac-ed out the soot, cleaned the pipe, and the cleanout on the chimney, thought I was good to go.  Now, the fire starts up good, temp goes up to 500 degrees on top of stove, and I throw the damper, to start the smoke burning.  Usually it kills the fire, after while, and I reopen the damper, get the fire going again, then at 500 I throw the damper again, and the fire will keep going, but it will die down and then flash up, causing smoke to come out the top door.  Getting the idea of how a wood burning truck works.  Can someone tell me how to get this stove to stop the huffing?  Beginning to think I should have bought the catalytic version.
My name's Jim, I like wood.

WH_Conley

I am not familiar with your stove. I had a stove one time that had an internal damper, it was just on or off. I had pretty much the same problem you describe. Put a damper in the pipe, problem went away. I guess it was dying out and when a little fresh air came in the bottom it would just flash, kind like a mini explosion. Just as a guess it is probably not "breathing" any, has to have a continuous burn, even if it is low.
Bill

Holmes

  Sounds like the  gasses are igniting inside the stove. Vvvaaboom sound?  I had a Jotul that would do that. I have a catalytic com-buster now and have not had that happen with this stove.
Think like a farmer.

Handy Andy

  Funny thing is, this only happens when the stove is cold, getting started.  Or sometimes when I want to turn the stove down, by reducing the air.  Usually once the stove is hot and working right, I can add wood and it's ok.  This morning, I cleaned out the ashes, put scraps in and started the stove up, it heated up to 500, I turned the damper to make it burn smoke, fire went black, opened up again, fire took off and came back up to 500, turned the damper again, and the fire kept burning, but it huffed about 6 times before burning right.
My name's Jim, I like wood.

beenthere

QuoteFunny thing is, this only happens when the stove is cold, getting started.

Let the stove warm up before flipping the damper. You may be getting a false reading of 500 and the stove still isn't warm enough to "run itself" with a strong enough draw.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Holmes

On my stove when inside the fire box reaches 500 degrees you can engage the com-buster . That is the temp to start burning the gasses in the smoke. I still think the gasses are igniting, giving you scary little explosions in the firebox ... Holmes
Think like a farmer.

sawdust


I had a similar problem with my Blaze king which has a catastrophic  converter. I found that I was using too small wood. It woofed so hard that it lifted the chimney off the top of the stove and set it to the side! Bigger wood so it gasses slower. I notice that they have drilled a hole in the supply damper so there is always a tiny fresh air supply. I think mine was drawing hard around the door seal until it reached a good mix and then would flash over.
Sawdust
comforting the afflicted and afflicting the comfortable.

jdtuttle

Here's a link with several possibilities. Look at the :"outdoor supply of combustion air"
jim
http://www.thechimneysweep.ca/2stackeffect.html
Have a great day

Al_Smith

If you just open up  the air and stack damper up a few seconds before you open the door it won't back draft on you .If you don't some stoves will huff fire like puff the  dragon .

John Mc

By "throwing the damper", do you mean adjusting the air inlet, or do you also have a damper in your flue above the stove? I don't have a damper at all in my flue, and don't need one... in fact, I'm told it will interfere with the proper operation of my stove (Hearthstone Pheonix, non-cat).

The huffing is usually caused by more gas being produced than there is air in the stove to burn it.  If the fire dies down, you are starving it for oxygen, so whatever you closed, you have probably closed it too far, or too soon (wood gives off a lot more gas early in it's combustion cycle).

A good place for wood stove operating tips:  www.woodheat.org

John Mc
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

Al_Smith

No stack damper ,really ? Seems odd but whatever works I guess .

John Mc

Quote from: Al_Smith on November 29, 2011, 09:59:52 AM
No stack damper ,really ? Seems odd but whatever works I guess .

Most of the newer woodstoves are better controlled by varying the air input, not the outflow through the stack.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

Handy Andy

  When I start a fire, I always have the air lever set for the most combustion air.  The damper I mention is the door you close when you want the stove to start burning the smoke.  There is a big ceramic thing in the back of the stove with a few about 1/4" holes, and the smoke goes through those holes, and when the ceramic is hot enough, the smoke burns, creating heat.  When it is working, the stove pipe gets cooler, you can put a hand on it without getting a burn, so the thing does work. I have a stove pipe thermostat on the top door of the stove, it's shaped like a griddle, and the directions say to get the stove up to 500, on that thermostat, and close the damper.  But it seems like it takes a while to get the ceramic block hot enough to work right.  Once it's hot, can add wood with no problem.
My name's Jim, I like wood.

WH_Conley

Look at your parts manual and see if that thing is not part #90 on the exploded view. The defiant is sold as a convertible stove. If that is what you are talking about with the holes, the converter is in place. I know nothing about catalytic stoves, never burned one. Also, check "damper adjustment", wouldn't be the first thing that ever left the factory that needed a little fine tuning. That is to say nothing of normal wear.
Bill

beenthere

Quote from: Handy Andy on November 29, 2011, 09:15:14 PM
  When I start a fire, I always have the air lever set for the most combustion air.  The damper I mention is the door you close when you want the stove to start burning the smoke.  There is a big ceramic thing in the back of the stove with a few about 1/4" holes, and the smoke goes through those holes, and when the ceramic is hot enough, the smoke burns, creating heat.  When it is working, the stove pipe gets cooler, you can put a hand on it without getting a burn, so the thing does work. I have a stove pipe thermostat on the top door of the stove, it's shaped like a griddle, and the directions say to get the stove up to 500, on that thermostat, and close the damper.  But it seems like it takes a while to get the ceramic block hot enough to work right.  Once it's hot, can add wood with no problem.

Now, you started out in your OP saying you had a non-catalytic stove. What you just described is what I have and the bee-comb like ceramic thing is referred to as the catalytic burner. Treat it with great care, and carefully vacuum the fly ash out of it or it will not draw air through it. I strongly suspect that is your problem. No hot gases are passing through that ceramic after-burner. I had the same problem.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Handy Andy

  Beenthere, there are 2 models of this stove, the one with the catalytic converter, and the one they call"non catalytic", but they both burn smoke. I used my shop vac on it when it was cold before firing it up last time.
My name's Jim, I like wood.

SwampDonkey

Quote from: Al_Smith on November 29, 2011, 09:59:52 AM
No stack damper ,really ? Seems odd but whatever works I guess .

None on my furnace and at my uncle's none on his stove pipe, it's controlled by the stove outlet with a slider knob and damper on the side with a slider. On my shop stove I do because it's a really old design with just a low tech damper plate.
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

Holmes

 Vermont castings has a combination stove ,cat and non cat is this that stove? It seems you have a catalytic you are engaging. If you add wood to a cat stove and do not use the proper sequence of operation ,disengage then re-engage the cat  when the stove gets hot enough you will get the problem you are having.  Holmes
Think like a farmer.

John Mc

It certainly does sound as though what you are describing is engaging the catalytic converter. (Vermont Castings does sell a stove that can be run as a cat or non-cat stove). You do NOT want to engage the converter until the converter is up to the appropriate temperature. Failure to operate this properly can muck up your converter. I don't have a lot of experience with cataylitic stoves, but I believe once the catalytic converter is solidly up to temperature, it tends to stay that way, even when adding more wood (as long as you dont't let things really burn out between charges of wood.

I suspect either you are just switching over to catalytic burn too early, or in the worst case, you have done that early switch often enough that the catalytic converter is contaminated or clogged (or maybe partly clogged). This MIGHT be why you got away with it the first year, but now as the contamination has built up, you are having problems.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

WI Fire

I have a VC Defiant Encore, 20 + years old. I use it in early fall, early spring, and occasionally in deep winter. I have replaced the catalyst block twice, and also taken it out and done the vinegar cleaning once. I don't part with it, because with the bimetallic strip temp. control, it's been superb. I likewise believe the chimney must be well heated, and the stove up to temp before moving to catalytic mode. I have seen flames 'puffing' similar to a backdraft if the temp. control on the right side of the stove is too far closed.

The other thing, is chimney length which influences draft. I have a good interior 30 plus foot run. If your draft is not good, you could also influence the starving effect.

tazz

I have the Dutchwest made by Vermont Castings with a catalyst. I have this problem sometimes and have to open the damper for a few seconds to let it vent. Usually adjusting the air inlet to give it a little more oxygen fixes this problem. I don't know how fast you are closing your damper after building a fire but I always wait until I have at least 1" of coals in the bottom and my firebox is at least 450 degrees F before closing the damper. Also if the temperature outside is mild you may not get the proper draft on your chimney that you get on a cold day.

Handy Andy

  I go for 500 degrees, the instruction manual shows where to put your stove pipe thermostat.  VC calls this stove their non- cat version, there is no cat, but it has a big block of something like firebrick with holes in it, which essentially does the same thing, just not supposed to burn out.  Found a video of a stove like mine huffing on U tube, by CLC Drama, if I were a computer geek, would put a link here.
My name's Jim, I like wood.

SwampDonkey

Just highlight the youtube link with the mouse with left mouse button down, copy (Ctrl-C) , then click in the post window with the mouse and hit Ctrl-V to paste into your post. I don't think the video will post unless you have a little text added to the post . Good to have tabbed browsing in your web browser, so you can click back and forth between web pages. Not the back/previous button. When copying and pasting with the mouse, the right button clicked brings up a edit menu to copy/paste as well.
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

Holmes

 Do you have the Everburn system? I saw something about this system. That person had a hot bed of coals , 600 degree stack temp then put dry wood in and closed the air damper. It seems like a very good system. Maybe going to 550 or 600 degree stack temp will help with your problem.  Holmes
Think like a farmer.

Handy Andy

  Think I'm learning something. Instruction manual says build a small fire to help with back puffing. So last evening I used shop vac to clean holes in ceramic back plate, then built a fire with 2 scrap boards. After about a half hour of burning, thermo showed 450 degrees, and I engaged the damper.  It continued to burn and left it alone for another half hour.  Wood was then coals, so put in 3 smaller pieces of split firewood. Seemed to be burning ok after a few minutes, so engaged damper.  Went upstairs.  Wife says the house is getting to smell like smoke.  So went downstairs, and the stove was going WHUFF.  So I disengaged the damper, let it burn a while, maybe 15 minutes, then reingaged damper.  Then it was ok overnite.  Very few coals this morning, but a few. Put in 2 small pieces of wood, burned for an hour before engaging damper, finally was burning ok without whuffing. Added some wood when first wood was coals, seems to be burning ok.  Seems the trick is to build a small fire in the biggest wood stove I could buy.  Jim
My name's Jim, I like wood.

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