Dutchwest 2184 problem

[lillyrat]

Been lurking on the forum for about a year now. Tonight I ran into a problem with my Dutchwest 2184 catalytic stove. I started leaking smoke around the stovetop/combuster gasket. I replaced this fall with 3/8 gasket but 7/16 was called for, but I couldn't find it anywhere. So anyway I think I will try replacing with 1/2. The part that scared me was that the combuster was humming along at 1100 degrees (air intakes were open 1 turn) when the smoke start coming out from under the stovetop. I immediately opened the bypass to alleviate the combuster pressure and everything seemed fine for about 2 minutes and then all off the sudden there was like a small burst of flames (seemed like a small explosion to me) or something in the stove and it puffed smoke out the air intakes. I had about 4 pieces of poplar and two of Hickory in there at the time. The outside temp is about 50 degrees, so I don't know if that has anything to do with the little explosive burst or what. The draft seemed fine as smoke was pouring out the chimney when I opened the bypass. Any help is appreciated.

Thanks,

 

[begreen]

The back puffing occurred due to a sudden accumulation of unburnt wood gas in the firebox when the bypass was opened. The same thing can happen in a conventional stove if one opened the ashpan door, then closed it before the wood was fully ignited. It is a small explosion and can be quite powerful and disconcerting.

In this area I would want a factory fit for the gasket. If not locally available in the correct thickness, I have to recommend that you order the correct Dutchwest gasket.

 

[webbie]

My first thought is that it is not the gasket that is making this happen. All gaskets - and even furnace cement joints (as you have seen!) will allow smoke to pass out through them, but the idea is that all small cracks in a system should be sucking air IN.

For whatever reason, you stove and chimney (and fuel) all together has an imbalance, which allows wood gas (wood smoke) to build up and then be ignited, causing what we call a "wood gas explosion", although that is obviously a strong term! This is something that happens to a lot of people in certain situations.

As an example of a situation that can cause this - if I used some wood that was VERY dry or had a lot of surface area (small pieces, etc.), and threw them in the stove, then kept the bypass and air controls (and maybe even the door) open to get everything lit. Then, when the bypass is closed there is all this wood which is "outgassing", in other words more "fuel" than the combustor can handle. So some of it heads up the flue or hangs around inside the upper part of the firebox, but since the combustor is hot (and so is the fire), it eventually ignites....when it ignites, it expands, therefore the smoke comes out.

Air leaks can aggravate this, for instance if the bypass of the stove does not seal tightly. Also, is the cat converter clean and pretty much dust free? Maybe it needs a little more secondary air (the top control)........

Bottom line is that many factors can combine to make this happen, but once you know what causes it you are more likely to attempt to run the stove in a way where it is less likely. For instance, you might want to not get the whole load too hot before closing the bypass, etc. Ideally, the wood will release it's gases at a slower and constant rate to be burned up by the combustor. In your case, for whatever reason, you were "flooding the engine" and it backfired.

 

[lillyrat]

Thanks for the reply. I guess I will have to order the gasket Kit. I was trying to avoid that since the only gasket I need is the combuster gasket. I looked all around for 7/16 and I couldn't even find anyone that could order it.

Thanks

 

[lillyrat]

I see that the little burst's I was getting were probably not related to a gasket problem, they were most likely the result of opening the bypass with a combustor temp of 1100. As far as the gasket issue goes, I am guessing (hate to say assuming but that is what I am doing I guess) that the gasket around the combuster is under more positive pressure that like a door gasket due to the fact that the draft can only go up and through the combustor / refractory and then out the top rear of the stove. Let me know what is really going on up there in the top of the stove.

Thanks,

 

[begreen]

Just so that I understand the terms here are you talking about the gasket surrounding the catalyst (interam) or another part?

 

[lillyrat]

I have been talking about the rope gasket that seals the stove to the combustor chamber. I think the interam gaskest is the one that sits around the base of the combustor itself. It was new this fall also. It sounds like I may have a seam leaking instead of just the rope gasket. From reading on here it sounds like I may need to to the flashlight inside the stove drill and fill seam / leak with stove cement. Please point me in the right direction. I guess I do know for a fact that the rope gasket sealing the stovetop / combustor groove is too small, so maybe I will start there and check the seams while I have the top off.

Thanks,
Steve

 

[lillyrat]

I guess I need to clarify how I was running the stove I may not have given enough information. From doing some searches, I think I may have been the cause of the smoke leaking into the house. I had the combustor engaged and was giving her full air (wide open) got her really cooking and then I shut the air down to one turn open. I maybe shouldn't run the combustor with full air. Let me know any thoughts on this. Do you think there is reason to go investigating leaks that may just be due to me operating the stove inproperly? Could the outside temps of 50 degrees had anything to do with it also? Thanks for all your help.

Steve

 

[BrotherBart]

For reference the 7/16" rope gasket is available here:

http://www.stovepartsunlimited.com/heading.asp?Section=Gaskets+&+Sealants&Heading=Per+Foot

 

[webbie]

Doesn't that stove have a top griddle (machined iron) which its above the combustor? That was the gasket I was thinking about...

and, yes, the temps can have to do with it. Warmer temps usually mean the air is laying lower, so is the smoke....solution is a couple things, as you seem to have found. Smaller loads, less air - and not fiddling with it until it has burned down. Burning in "cycles" is very important to some stoves.

 

[lillyrat]

Thanks for the replies and the supplier for the gasket. I tightened the top / griddle today in hopes that in heat cycling, the bolts had backed out a little. They weren't as tight as they could be. It it a problem to run the combustor with full air to try and really get the heat out of the stove? That is my main question right now. I am going to try and burn today, just not get it roaring so much with the combustor on. Also the outside temp is about 30 today. Thanks again for all the information you are nice enough to share with a newbie.

Steve

 

[begreen]

VC warns not to burn the stove too hot with a fresh load of very dry wood. Too high temps may shorten the life of the combustor. If any part of the stove is glowing, it is too hot and being overfired.

 

[lillyrat]

I have yet to overfire the stove that I know of. I monitor the flue temp religously and have never let it get above 550 degrees, I rarely monitor the stove top temps since the flue seems to trump the stovetop temp when it comes to safety. I have only seen stove top temp up to 500 once when I was running full air on the combustor. Flue temps started to rise, telling me it was time to back it down a little. I sometimes wonder if I don't burn a little to much on the conservative side. I am the nervous type so unless I am sitting right in front of the stove I rarely have the air open more than 1 turn.

Thanks,

 

[webbie]

Running the secondary (combustor) air full open is unlikely to give you more heat. In fact, in general I would set that control at a certain point and just leave it there - then us primary air and fuel load to adjust the heat.

 

[lillyrat]

I need to clarify again, I was referring to running the combustor wide open, when what I actually meant was that I was running through the combustor, with primary air wide open, which was giving very high temps in the firebox I guess. Sorry again for the confusion. I will learn to better describe what conditions I am running at. Sorry for the confusion and I again thank you for continuing to help me along the way.

Thanks