Question Catalytic Stoves and Creosote

[webby3650]

I suppose all these EPA stoves run at about 80% efficiency. So in the 20% of unburnt matter, in BK's case due to such low stack temp, it accumulates on the pipe. Without any visible smoke.

I remember reading posts from Backwoods Savage and the way he ran his Fireview. He claimed, not needing to clean the pipe for 4-5 seasons easily.

After installing my completely rebuilt encore 2550 back in early Nov. I have been going pretty much 24/7 (with few exceptions, couple warm spells and a vacation). My stack temps (internal probe) hover around 200 and 400*f (never exceeding 400).
I just pulled the cap off and if I get a tea cup of creo at the end of the season I will be surprised, 22' stack.

There must be something else going on with the BK technology (no visible smoke yet some black accumulation of creo).

Keep in mind that only a few people on this site are reporting black creosote build up. I clean a dozen or so BKs annually, I rarely see any abnormal accumulation. I see lots of clogged or nearly clogged stoves, there is no association between cat and non-cat in my opinion. It's how the stove is operated, and the fuel that's put through it.

 

[Diabel]

Keep in mind that only a few people on this site are reporting black creosote build up.

So true. Sometimes we forget this and generalize.

 

[Highbeam]

Keep in mind that only a few people on this site are reporting black creosote build up. I clean a dozen or so BKs annually, I rarely see any abnormal accumulation. I see lots of clogged or nearly clogged stoves, there is no association between cat and non-cat in my opinion. It's how the stove is operated, and the fuel that's put through it.

Perhaps the terminology I used was part of the problem with this thread. I stated that the BK produced double the amount of creo that my hearthstone did, and that it is black instead of brown. This is true but you have to consider that the hearthstone barely made any creosote at all. I don't have any excessive build up or abnormal accumulation in my chimney above my BK. Once a year I sweep it and only get a small amount but it is black and it is much more than I got with the hearthstone.

Everybody gets build up in their chimney. Some black, some brown, and some even white. Some folks get so much build up that their entire chimney is 100% blocked. That's bad but some folks won't clean their chimneys until that point. Some folks even depend on a chimney fire to clean their chimneys.

In my experience, the BK cat stoves do not make excessive creosote. Even when run on the lowest possible settings for extended periods.

 

[Highbeam]

I suppose all these EPA stoves run at about 80% efficiency.

Not even close. The best cat stoves get into the low 80% range. The rest of the EPA pack is way way lower. Some non-cats like my old hearthstone burn with a very low emissions rate but send huge amounts of heat up the stack so low efficiency/low emissions. Better stoves like the Woodstock hybrids are able to accomplish high efficiency while accomplishing low emissions, much better.

My princess is the second most efficient stove on the market last I checked but makes a pretty medium gph emissions rate of 2.5 or so. BUT, awesome burn times unmatched by others. The larger IS from Woodstock is getting close though.

What makes creosote? Is it mostly the condensation of water/unburnt volatiles in the flue? Is it actually an accumulation of the particulate that is disclosed in the particulate emissions rate? A combination? We know that if you try hard enough that you can make a low emissions stove burn dirty and a high emissions stove burn cleanly. Smoke and/or creo accumulation.

 

[webby3650]

Not even close. The best cat stoves get into the low 80% range. The rest of the EPA pack is way way lower. Some non-cats like my old hearthstone burn with a very low emissions rate but send huge amounts of heat up the stack so low efficiency/low emissions. Better stoves like the Woodstock hybrids are able to accomplish high efficiency while accomplishing low emissions, much better.

My princess is the second most efficient stove on the market last I checked but makes a pretty medium gph emissions rate of 2.5 or so. BUT, awesome burn times unmatched by others. The larger IS from Woodstock is getting close though.

What makes creosote? Is it mostly the condensation of water/unburnt volatiles in the flue? Is it actually an accumulation of the particulate that is disclosed in the particulate emissions rate? A combination? We know that if you try hard enough that you can make a low emissions stove burn dirty and a high emissions stove burn cleanly. Smoke and/or creo accumulation.

well said!

 

[webby3650]

Hearthstone stoves do waste tons of heat up the flue! They rarely ever have a dirty flue, and it's certainly not due to their efficiency. That stone can only release a certain amount of heat through the stone, the rest goes up the flue.

 

[Patapsco Mike]

I've burned a lot of different stoves over the years both cat and non-cat. I'm careful with what I burn and I measure my wood with a moisture meter before burning it. My BK makes a mess of my flue cap in the way no other stove ever did. The flue itself below the cap stays very clean, barely worth cleaning after a full season of burning- but the cap itself (mostly the screen that keeps birds out) will get severely gunked up. Once each winter I'll climb up, remove the cap, and clean it off with a brush. Takes just a few minutes. The rest of the 20' of pipe gets brushed once a year and I always think to myself I could have easily gone another year.

 

[webby3650]

I've burned a lot of different stoves over the years both cat and non-cat. I'm careful with what I burn and I measure my wood with a moisture meter before burning it. My BK makes a mess of my flue cap in the way no other stove ever did. The flue itself below the cap stays very clean, barely worth cleaning after a full season of burning- but the cap itself (mostly the screen that keeps birds out) will get severely gunked up. Once each winter I'll climb up, remove the cap, and clean it off with a brush. Takes just a few minutes. The rest of the 20' of pipe gets brushed once a year and I always think to myself I could have easily gone another year.

That's why I don't have a screen on my cap. Many manufacturers have made the screen an option, rather than standard equipment for this very reason.

 

[BKVP]

That's why I don't have a screen on my cap. Many manufacturers have made the screen an option, rather than standard equipment for this very reason.

I removed my screen 18 years ago. I burn 15-18% fuel this past winter with little to no accumulation. I did previously burn NIELS but switched back to cord wood this past winter. With NIELS I inspected my chimney each year but swept it every 3 years. NIELS are 7% moisture content. If you get any significant amount of build up, look at fuel, chimney or operator....it's not the stove.

 

[toddnic]

I currently have a Pe Super 27, which is a great stove. We will soon be looking for a stove with a larger firebox and are considering a catalytic stove due to lower emissions and longer burn times.

Do the catalytic stoves run with a lower chimney temperature and if so, does this cause more creosote formation?

Thank you all for your help.

I can't specifically answer your question but I can give you my experience. I get about 1/2 gallon of creosote from my chimney each year. I burn around three cords of wood each year. It seems fairly minimal to me..... I have a Progress Hybrid.

 

[webby3650]

I can't specifically answer your question but I can give you my experience. I get about 1/2 gallon of creosote from my chimney each year. I burn around three cords of wood each year. It seems fairly minimal to me..... I have a Progress Hybrid.

I burn 3 cords+ each season and get a cup or maybe 2. Is your flue exceptionally tall?

 

[begreen]

That is what I also see, about a cup or less for 3 cords. Even with the identical wood it's going to vary with how low the stove is run and the chimney. If the house is easily heated with say 12K BTUs then it's going to be running on low most of the time. Now vent the stove to an exterior chimney and it is going to get dirtier than a stove that is run at 25K BTUs thru a straight-up interior chimney, The low BTU output is going to have a cooler flue gases. Add an exterior flue and more creosote is going to condense.

 

[toddnic]

I burn 3 cords+ each season and get a cup or maybe 2. Is your flue exceptionally tall?

I have 15 feet of chimney. I have been burning wood that until this year was not as seasoned as what it needed to be. I'll have this year's totals later this month when I clean the chimney again.

 

[DUMF]

I conclude that yes and yes. In my home with all vertical, double wall, chimney I burn excellent three year seasoned softwood. I heat 100% with wood. I switched from a noncat hearthstone heritage (about 30 cords burned) to a blaze king princess catalytic stove. The flue temperatures on low burn are about half as high with the catalytic stove and the creosote accumulation is about double with the catalytic stove. The cat creosote is black and crunchy but the non-cat was brown and crunchy.

These drawbacks are insignificant when compared to the wonderful, beautiful, awesome benefit of thirty hour burn times and very low burn rate possible with a catalytic stove. I have a 9 month long burn season and 95% of the time I am burning low and slow. We love the long burn times possible with the cat stove.

Shouldn't be with proper cat operation. Ask the BKVP and cat users. If you do it right allowing the cat to "light off" at a high enough temp AND then give it time to get back up to working temp, there WILL be a clean burn. The non cat stove tubes often don't get hot enough with low seasoned or wet wood, or tough to season species such as oak. Non cat users often don't give the load time to coal and heat the tubes to reburn partially burnt gases.
Even with older technology cat stoves from the late 90's, chimney creosote was near nothing each season. It's technique and the little extra step with cats that many don't do. We never got "crunchy" stuff....ever.

 

[kennyp2339]

I use to burn a us stove 2500 (The tube stove) then switched to a BK princess. While burning the tube stove my chimney would get build up, ashy with some black crunch in the pipe it self, the chimney cap kept relatively clean. The BK is opposite, my chimney pipe stays very clean, what every build up is usually a grey brown powder ash, my cap looks horrendous, almost like little black icicles or frozen black drip which is actually creosote. I much rather burn the BK cat over the tube stove.

 

[Dobish]

I was thinking about this the other day, but if my flue temps when the cat is engaged hover around 200º (single wall black pipe, infared thermometer), cat temp at 1000º, and griddle temp at 375º-400º, should I be concerned?

I am not getting any smoke out of the chimney. I can turn up the airflow and get the flue temp higher, but it seems unnecessary to me.

The room is plenty warm (72-74º), so i want to maintain temps, not raise them.

 

[begreen]

Surface temps on single-wall will always be lower. 200F exterior is probably around 300F interior temp.

 

[Dobish]

Surface temps on single-wall will always be lower. 200F exterior is probably around 300F interior temp.

that was my thinking, but don't have a probe to verify. I figure with a secondary combustion and a cat, with dry wood, i am not sending a ton of stuff into the air.....

 

[shoot-straight]

I am almost exactly like highbeam. Had a hearthstone. Burned it hot and literally had no creo. None. Cleaned pipe every other year. Coffee cup of brown stuff. Switched to bk ashford. Had lots of the black crunchy stuff at top and clogging the cap after a year. Tall insulated liner 26' or so in masonry chimney.

I will say that Chris sent me a new cat last year, made a huge difference in heat produced immediately. Original was simply not working right. I expect to see a reduction in creo now.

 

[Diabel]

I have a probe 18" above the stove and it always reads between 300* - 400*. The 400 will be when the cat is screaming at 1650!!