Dirty Glass - Clean Chimney?

[leeave96]

I turned down my cat stove last night - damper almost all the way closed for an overnight burn. Left the stove with a glowing cat and a full firebox of wood, no flames visible, a few glowing coals in the bottom. After 8 or so hours, the stove had a nice bed of coals left over and the glass was colored medium to light brown.

Threw a few splits on, opened the damper up and in no time the stove was cranking out serious heat again and the brown burned off the glass fairly quickly.

With the temperature moderating a bit, I am going to try this type of burn and see what kind of build-up I may get doing it.

My question is - if the glass is turning brown on a smoldering fire, how much creosote, if any, is getting by the cat? I'm thinking that very little if any since the cat is fired-off and glowing. Since there is not a lot of air volume moving through the stove due to the low damper setting and the cat is glowing, the creosote is being burned. The colder glass and stove sides are where any lingering creosote may condensate out as the smoke swirels around the firebox waiting to go through the cat.

Just courious - anyone have a cat stove with a dirty glass, but a clean chimney with these ultra low burns?

Any Woodstock owners burned their cat stoves with the damper closed all the way with a cat glowing? I haven't tried this yet - but it's tempting.

Thanks!
Bill

 

[cmonSTART]

Little to none. That sounds pretty typical for a low burn on a cat stove.

 

[leeave96]

Did an overnight burn last night with pretty much cat only burn and to my surprise my glass was fairly clean. Lots of coals left over, stove top at about 350 and about 72 degrees in my living room - yippie! But, the overnight temp was about 30 degrees outside and we are having a cold front move through this weekend so back to lively flames and plenty of heat.

It's really interesting testing out this stove to see how it performs on the shoulder burns. I really like the ability to drastically turn down the stove - we'll see on the creosote build-up in a few weeks when I check the stove pipe and liner.

When the outdoor air temp goes up again, I'm going to try closing the damper to the point of being closed. One thing on the Keystone is there is a hole in the ash pan housing that lets air in from the bottom of the stove so if I close the damper all the way, there is still some air making it's way into the stove and I've got enough draft on my chimney to suck that air through the stove.

Bill

 

[Fsappo]

If you see little or no smoke comin out the chimney, life is good.

 

[Todd]

I've never tried turning either of my stoves down to 0 air. Seems like when I turn it down too much I sometimes get those run away 700+ temps. Always keep a little red and flame in the fire box and still have no problem obtaining overnight burns.

Did you find that leaving the hole unplugged lets you turn the stove down further? I unplugged mine for the last few burns and still think it burns up quicker this way but I'm only turning it down to about .8-1, I'll try going lower tonight and see what happens.

 

[leeave96]

I've never tried turning either of my stoves down to 0 air. Seems like when I turn it down too much I sometimes get those run away 700+ temps. Always keep a little red and flame in the fire box and still have no problem obtaining overnight burns.

Did you find that leaving the hole unplugged lets you turn the stove down further? I unplugged mine for the last few burns and still think it burns up quicker this way but I'm only turning it down to about .8-1, I'll try going lower tonight and see what happens.

Todd,

I am keeping the hole unplugged mostly because it puts air under the coals, keeps them hot (my hearth is hotter under the stove with the hole unplugged too) and burns them down to ashes quicker. The reason I do this is to lower the level of coals when reloading. With such a small firebox, all available space to get splits into the stove is a premium and since I have been operating this way, my coals level never gets up to the glass anymore. It also seems that with the air coming up from the bottom, alot of the the fine ashes fall through the slits in the stove bottom to the ash pan without me having to rake them around as much. I do burn more wood, but I am also trying to get more heat too - so that's OK. One thing about having a little air come in from the bottom is that splits at the rear base of the firebox seem to burn down better as some air gets to them and I figure that if I want more heat, the back of the stove ought to be throwing heat out too - after all there is a goodly bit of soapstone on the rear too near the base. So far I am very happy with the stove performance with the ash pan housing hole open vs closed (and it is much helped with my new liner and the draft I gained) I also think I am getting more heat off the top of the stove since I went to a rear flue exit set-up.

Reason I am thinking that a zero damper setting may be possible on the Keystone without hitting the 700 degree limit is a combo of things. Firstly, given the small firebox, there is a limit on how much smoke volume if going to get to the cat vs a Fireview. I also think about the non-cat stoves where the folks turn the primary air off and the secondary air all the way down. You kind of have this with the Keystone in that the hole on the ash pan housing sort of acts like a secondary air source - turned all the way down like a non-cat stove. So there is always some air coming into the stove even if the damper gets shut down to zero or near zero. I'm not sure you can go to zero on the Fireview, but I think Dennis has posted damper setting on his at 1/4 open with good results. That may be the equivalent to the Keystone on zero and relying on the ash pan housing hole to feed air into the stove.

I've always liked to have flames and heat throwing off my stove, but it got really cold and stayed cold after I installed it - so not much need for cat only driven heat, but this last week temps moderated and I wanted to give it a try. I'm still learning my stove so take my results with a grain of salt.

Thanks,
Bill

 

[Todd]

I've never tried turning either of my stoves down to 0 air. Seems like when I turn it down too much I sometimes get those run away 700+ temps. Always keep a little red and flame in the fire box and still have no problem obtaining overnight burns.

Did you find that leaving the hole unplugged lets you turn the stove down further? I unplugged mine for the last few burns and still think it burns up quicker this way but I'm only turning it down to about .8-1, I'll try going lower tonight and see what happens.

Todd,

I am keeping the hole unplugged mostly because it puts air under the coals, keeps them hot (my hearth is hotter under the stove with the hole unplugged too) and burns them down to ashes quicker. The reason I do this is to lower the level of coals when reloading. With such a small firebox, all available space to get splits into the stove is a premium and since I have been operating this way, my coals level never gets up to the glass anymore. It also seems that with the air coming up from the bottom, alot of the the fine ashes fall through the slits in the stove bottom to the ash pan without me having to rake them around as much. I do burn more wood, but I am also trying to get more heat too - so that's OK. One thing about having a little air come in from the bottom is that splits at the rear base of the firebox seem to burn down better as some air gets to them and I figure that if I want more heat, the back of the stove ought to be throwing heat out too - after all there is a goodly bit of soapstone on the rear too near the base. So far I am very happy with the stove performance with the ash pan housing hole open vs closed (and it is much helped with my new liner and the draft I gained) I also think I am getting more heat off the top of the stove since I went to a rear flue exit set-up.

Reason I am thinking that a zero damper setting may be possible on the Keystone without hitting the 700 degree limit is a combo of things. Firstly, given the small firebox, there is a limit on how much smoke volume if going to get to the cat vs a Fireview. I also think about the non-cat stoves where the folks turn the primary air off and the secondary air all the way down. You kind of have this with the Keystone in that the hole on the ash pan housing sort of acts like a secondary air source - turned all the way down like a non-cat stove. So there is always some air coming into the stove even if the damper gets shut down to zero or near zero. I'm not sure you can go to zero on the Fireview, but I think Dennis has posted damper setting on his at 1/4 open with good results. That may be the equivalent to the Keystone on zero and relying on the ash pan housing hole to feed air into the stove.

I've always liked to have flames and heat throwing off my stove, but it got really cold and stayed cold after I installed it - so not much need for cat only driven heat, but this last week temps moderated and I wanted to give it a try. I'm still learning my stove so take my results with a grain of salt.

Thanks,
Bill

When I asked Woodstock about this hole and if it was there for the EPA so you couldn't close the air off, they said no, the air slide is still slightly open even at 0 and the reason for the hole was to help complete combustion durning the coaling stage. So everything your saying makes sense in why they drilled a hole in the ash pan. There also has to be a small amount of air through those holes in the air wash plate above the glass to help combustion in the cat or it will stall out which the EPA would frown upon.

 

[Backwoods Savage]

Bill, we have ran the Fireview with the draft closed several times last year. For some odd reason for a time last year we had a problem with the stove wanting to run hot. To stop it, we would open the bypass until the temperature started dropping and then open the draft to about the .75 where we normally run it and all was well. We too try to keep a little flame in the firebox and don't have problems (normally) with anywhere near overheating.

There was one time just recently when I went to bed early and the wife set the final draft. When Mother Nature woke me, I naturally walked out to check the stove. There were no flames and very few red coals but the cat was glowing bright red. The stove top temperature was 650. I slid the draft to .75 and all was well the rest of the night.

On very cold days or nights we will then leave the draft open to 1 and on rare occasions at 1.25 but that also depends upon what wood and how much of it we have in the stove.


EDIT: For what its worth, I don't feel there is much difference in length of burn if the draft is set very low, producing no flame, vs setting the draft so you have some flame.

 

[Todd]

Just to continue the conversation, I did some experimentation and turned my Keystone down to .5 to see what would happen. Flames went out, cat turned bright red and there were still some red coals in the bottom. Temp shot up to about 620 and held. After 30 minutes the fire box burst into flame and then I had about 45 minutes of those floating flames. I played with the air setting and turned it all the way down past 0 or fully shut. Still had a glowing cat and red coals for 15 minutes before turning it back up to .5. While it was at 0 I played with the ash pan hole and when it was plugged the coals would darken and start ot go out, open it up and they would come back to life, so it does make a difference. I'm coming up on 12 hour burn and there is still a chunk of Oak in the back with a little red under it, will be reloading soon and will continue burning both stoves at 12 hour intervals. Pretty impressed with this little Keystone burning 12+ hours and even keeping the glass nice and clear.

 

[Backwoods Savage]

That is interesting Todd. What you describe with the flames suddenly burst with those floating flames is exactly what we get if we turn the draft down further. It is sort of nice to watch, especially for anyone who has never seen this. All in all, it sounds like you have everything well under control.....except for the weather.

 

[Todd]

Yeah, I see this kind of flame in the Fireview as well but I can't turn it down as far as the Keystone. The coals would go completely out and the stove top temp can sometimes jump up over 700. I think that little hole in the ash pan makes a difference.