Keystone stack smoking??

[Woody Stover]

I had a load going, closed the bypass and cut the air back to about .3. I had the floating flame at the top of the glass, but the combustor wasn't glowing. I went outside to take a look...fairly heavy smoke coming out of the stack. I went back in and opened the air to about .8, got more flame, and the combustor kicked in. Then I cut the air all the way back. Combustor got to glowing brightly. No smoke coming out.
What gives? I thought the combustor was supposed to be burning any available smoke, no matter what was going on in the firebox. I also thought that just because the combustor wasn't glowing did not mean it wasn't working. Apparently that's not the case here. One reason I bought this stove was because it is rated low in emissions. I don't want to be bothered with having to make sure that the combustor is doing its job, and adjusting the burn if it isn't. Any ideas? Any Keystone burners had this problem?

 

[certified106]

Never owned a Keystone but what you just described above is the inherent nature of a catalytic stove. Every time I have ever put a load of wood in my previous catalytic stove if I didn't get the cat to at least 1000° and glowing before shutting the air back it would smoke until I opened the air back up and and let it get to the point it was starting to glow. Next time leave the primary air open longer after shutting the bypass damper an allow the cat to get hotter and you shouldn't have any problems.

 

[Woody Stover]

Every time I have ever put a load of wood in my previous catalytic stove if I didn't get the cat to at least 1000° and glowing before shutting the air back it would smoke until I opened the air back up

When I first engaged the combustor it began to glow. I figured once it was burning, the burn would be self-perpetuating and continue until there was no more smoke.
This behavior isn't a fluke; It did the same thing last night. Maybe I didn't watch my Dutchwest closely enough to see if it was cutting in and out like this one seems to do. I don't recall smelling smoke once the cat was lit off, though...
I want to get a combustor probe for the Keystone, but haven't got around to it yet.

 

[certified106]

Every time I have ever put a load of wood in my previous catalytic stove if I didn't get the cat to at least 1000° and glowing before shutting the air back it would smoke until I opened the air back up

When I first engaged the combustor it began to glow. I figured once it was burning, the burn would be self-perpetuating and continue until there was no more smoke.
This behavior isn't a fluke; It did the same thing last night. Maybe I didn't watch my Dutchwest closely enough to see if it was cutting in and out like this one seems to do. I don't recall smelling smoke once the cat was lit off, though...
I want to get a combustor probe for the Keystone, but haven't got around to it yet.

The cat still wasn't hot enough. I have seen mine begin to glow, then shut it down to quickly and had it go out it's just how they are. I could literally tell from the shade of orange that my cat was whether it was going to stay lit or not. Usually if it was between 1000 and 1100 with the whole combustor glowing a bright orange it would stay lit. If just the bottom of it was glowing and I shut it down it would quickly fall below 800° and there would be visible smoke out of the chimney. It's just a process of learning what it takes to get it lit off and keep it that way. As a side note the warmer it got outside the more careful I had to be not to shut it down to quickly as the draft is reduced due to warm weather. My temps and times may not be the same as yours so you will just have to play with it and get used to what it takes.

 

[pen]

The cat still wasn't hot enough. I have seen mine begin to glow, then shut it down to quickly and had it go out it's just how they are. I could literally tell from the shade of orange that my cat was whether it was going to stay lit or not. Usually if it was between 1000 and 1100 with the whole combustor glowing a bright orange it woudl stay lit. If just the bottom of it was glowing and I shut it down it would quickly fall below 800° and there would be visible smoke out of the chimney. It's just a process of learning what it takes to get it lit off and keep it that way. As a side note the warmer it got outside the more careful I had to be not to shut it down to quickly as the draft is reduced due to warm weather. My temps and times may not be the same as yours so you will just have to play with it and get used to what it takes.

Well said in all regards. Remember, a catalyst is not a filter. In chemistry, there is a lot of uncertainly about WHY a catalyst allows chem reactions to take place w/ less activation energy, but they do. The problem is the reactions that you want to occur need a ton of energy to take place, while a catalyst reduced the temp needed for it to happen, it still needs a lot of energy (heat) to allow it convert your nasties into even more heat and cleaner exhaust.

pen

 

[leeave96]

The ulitmate test for the cat - to see if it is working is not if it is glowing, but if smoke is coming out of your chimney.

Another thing that you need for the cat to burn is air. Sometimes when you load the stove, get a glow in the cat and then damper down is reduce the air ratio vs the amount of smoke in the firebox and it snuff out the cat. Just open the damper to get more air in, or open the bypass and let the wood get hotter and more charred or leave it. Sometimes you can leave the cat engaged, though it is not lit and it will light off later on it's own as the fire settles and the smoke clears out. The cat is not a block off plate, so you can engage it even if it is not burning and air goes up the chimney and combustion is taking place. One thing NOT to do is engage the cat where moisture can boil off onto it - not good. Having said all that, I like to get my cat to fire-off everytime, but there have been a handfull of times when I need to hit the sack for the next work day and loaded the stove, engaged the cat, stove top was under 200 degrees, no cat firing-off, smoke coming out the chimney and get up later in the night and find a nice 450 to 500 degree stove top temp and a very clean cat burn going on.

Another thing you can do that helps is give your cat a quick cleaning. I can have mine in and out in 10ish minutes through the block-off plate on the top (as mine is rear vented). I think if you are venting from the top, it's even easier getting the cat out from the rear.

Great stove - keep learning it.

Bill

 

[Todd]

Sounds like the cat stalled due to cutting back the air too soon. It happens to me sometimes when I'm in a hurry. The cat acts like a damper in a stove and if you cut back the air too soon it could cool down and stall. I like to engage the cat at about 1.5 on my Keystones, then turn it down to desired burn rate after about 10-20 minutes, this helps ensure the cat and draft are going good and no chance of a stall.

 

[Woody Stover]

the warmer it got outside the more careful I had to be not to shut it down to quickly as the draft is reduced due to warm weather.

Hmmm, OK. That could have been a factor. It wasn't cold last night, more like cool, but I decided to fire up anyway. And I have been cheating it a bit, seeing if it will light off even though the stove top isn't up to the recommended 250*, trying to use as little wood as possible in getting up to cruise. I thought that last night, the stove top was up around 300* before I cut back to .3 and started having the problem...but I'm not certain.
I'll probably have a few more chances to burn this Spring. I'm glad I went ahead and installed the new flue and stove this season. I should have it down and be ready to rock next Fall.

One thing NOT to do is engage the cat where moisture can boil off onto it

Another thing you can do that helps is give your cat a quick cleaning.

I've been pretty careful to make sure any marginal wood is done hissing before I close the bypass. And, surprisingly, this dead standing Black Oak I just cut is around 15% with no hissing going on.
I'll definitely pull the cat and check it out. It could conceivably have a bit of fly ash inside. I can see a little when it's glowing. It didn't look excessive to me, but maybe it's just enough to make the difference.

I've also been thinking that a steel cat might stay lit more easily. My stove shipped with the ceramic.

Thanks, everyone, for your help!

 

[Backwoods Savage]

Sounds like the cat stalled due to cutting back the air too soon. It happens to me sometimes when I'm in a hurry. The cat acts like a damper in a stove and if you cut back the air too soon it could cool down and stall. I like to engage the cat at about 1.5 on my Keystones, then turn it down to desired burn rate after about 10-20 minutes, this helps ensure the cat and draft are going good and no chance of a stall.

Todd, we finally had that happen to us. But it is a quick and easy fix.

 

[Todd]

Sounds like the cat stalled due to cutting back the air too soon. It happens to me sometimes when I'm in a hurry. The cat acts like a damper in a stove and if you cut back the air too soon it could cool down and stall. I like to engage the cat at about 1.5 on my Keystones, then turn it down to desired burn rate after about 10-20 minutes, this helps ensure the cat and draft are going good and no chance of a stall.

Todd, we finally had that happen to us. But it is a quick and easy fix.

Yeah, this is the time of year when it happens more often. I need to use a little more air during the shoulder season due to sluggish draft.