Burning cat stove without engaging the cat

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Eman85

Minister of Fire
Oct 10, 2022
1,117
E TN
Spinoff from the burning techniques thread.
I am burning my stove without engaging the cat as I type this, been burning continuously like this for 2 days now. I've burned it like that for a few seasons when I didn't want to buy a new cat. I can make my stove work for me without the cat with no problems, actually much simpler to run. I can get overnight urns with no problem. I am aware of my chimney condition, and I do my own cleaning. I generally always get mild weather and I can easily go on my roof and run the brush down the stainless chimney. I have a STT thermometer and my flue temp thermometer is on the adapter that goes from oval to round just below the DW stove pipe. Without the cat there is a lot less anxiety. I can operate it with the cat and I have a temp probe on it. I can have great burns with the cat and then it goes into overheat and I struggle to get it cooled down. With the cat it also back puffs when the cat is glowing and the gasses build in the firebox. But with the cat it does clean up the smoke so the chimney stays cleaner. With the cat I can get low, long slow burns and the house doesn't overheat. Without the cat the house gets a lot hotter.
 
Spinoff from the burning techniques thread.
I am burning my stove without engaging the cat as I type this, been burning continuously like this for 2 days now. I've burned it like that for a few seasons when I didn't want to buy a new cat. I can make my stove work for me without the cat with no problems, actually much simpler to run. I can get overnight urns with no problem. I am aware of my chimney condition, and I do my own cleaning. I generally always get mild weather and I can easily go on my roof and run the brush down the stainless chimney. I have a STT thermometer and my flue temp thermometer is on the adapter that goes from oval to round just below the DW stove pipe. Without the cat there is a lot less anxiety. I can operate it with the cat and I have a temp probe on it. I can have great burns with the cat and then it goes into overheat and I struggle to get it cooled down. With the cat it also back puffs when the cat is glowing and the gasses build in the firebox. But with the cat it does clean up the smoke so the chimney stays cleaner. With the cat I can get low, long slow burns and the house doesn't overheat. Without the cat the house gets a lot hotter.

I do burn without the cat on occasion.. I definitely dont try to burn overnight like that and cutting the air back is a big no,no.. I dont do it alot for some.of the reasons you mention.. I can't burn extended time like this.. my living room feels like Africa in August..

The dirty stovepipe for me is a big concern. Like you I have a roof the is easy to access and Im still young enough and very nimble to get up there and clean it myself.. Im normally up on the roof 3xs a year cleaning the stovepipe, checking the gutter guards and my solar system, shingles.. ect
 
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I'm not young but I'm retired and have the time to check the chimney.
I burned overnight last night. On the way to bed at 12 I threw about 1/2 load of splits in. Mostly smaller splits all very dry oak. Turned the air down to about 30-40% open. Woke at 8 and there was a nice bed of coals, opened the air and threw a couple of small splits in and we're off again. It's nice to be able to just load it and go to bed not play for an hour to get the cat to settle in before bed.
My stove is an antique and was the first cat stove VC made. It's just a downsized Defiant with the cat added.
 
I'm not young but I'm retired and have the time to check the chimney.
I burned overnight last night. On the way to bed at 12 I threw about 1/2 load of splits in. Mostly smaller splits all very dry oak. Turned the air down to about 30-40% open. Woke at 8 and there was a nice bed of coals, opened the air and threw a couple of small splits in and we're off again. It's nice to be able to just load it and go to bed not play for an hour to get the cat to settle in before bed.
My stove is an antique and was the first cat stove VC made. It's just a downsized Defiant with the cat added.


so its like an encore
 
It is an Encore, the first model of it, sold as a Defiant Encore. Cat goes in through a panel in the back.
 
Figured I'd update on my recent burn
Last night outside temps warmed up , low 50's dropped to 40's, so I didn't put much in the box. Last wood was about 9PM , less than 1/2 box, and I had turned the air down pretty low as the house got pretty hot. Went to bed at 12 never put another piece in. Today rainy and 50's at Noon I was going to empty ashes hadn't done anything to the stove aside from open the air all of the way about 8AM. I went to rake the ashes and had plenty of coals. I tossed a couple of pieces of dry kindling in and fire lit right off. So basically a 15 hour burn on a 1/2 box without using the cat.
 
Figured I'd update on my recent burn
Last night outside temps warmed up , low 50's dropped to 40's, so I didn't put much in the box. Last wood was about 9PM , less than 1/2 box, and I had turned the air down pretty low as the house got pretty hot. Went to bed at 12 never put another piece in. Today rainy and 50's at Noon I was going to empty ashes hadn't done anything to the stove aside from open the air all of the way about 8AM. I went to rake the ashes and had plenty of coals. I tossed a couple of pieces of dry kindling in and fire lit right off. So basically a 15 hour burn on a 1/2 box without using the cat.
lol you are just frying peoples brain with this post.
 
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lol you are just frying peoples brain with this post.
Not really. I'll find hot coals in an open ash pan after that amount of time. No biggie.

A few hot coals is not the same thing as a long burn with useful heat, especially when you're sending a lot more of it up the chimney than you would with a working cat.
 
Not really. I'll find hot coals in an open ash pan after that amount of time. No biggie.

A few hot coals is not the same thing as a long burn with useful heat, especially when you're sending a lot more of it up the chimney than you would with a working cat.
I dont know that Im sending alot of heat up my chimney without a cat in. Maybe I am? What would be the proof? Ive tried with both the cat in and out, and after watching my probe spike into the danger zone w/ cat, fiddling with air control and never really understanding what will keep it down while maintaining the heat I want, I remove it when I burn hotter than normal. It's just more predictable and easy to use without the cat in.
At all times I can wake up with coals without the cat. If it's really cold out I wake up to enough to restart the stove easily with a few splits to get the stove back up to temp and burn off anything that may be on the glass. When it's not that cold out I set the air a bit lower, I wake up to big coals and pieces that I can stir up and let that run for a few hours before needing to add anything. If anything I feel like having the cat in somehow increased my draft, but then it would sometimes stall it a bit leaving me scratching my head as to why I would wake up some days with coals and other days not as much, doing the same thing. With the cat out, my stove is much more predictable unless Im burning really low/slow then the cat has helped.
I may try mid winter for a few weeks to force myself to use the cat and figure out it's quirks, to see if I can extend my burns. But if I can't extend my burns without sacrificing heat, then why bother
 
Great thread, It's just wild to hear your performance without the Cat.
 
The VC flexburns are supposed to burn nearly as well without a cat as with one and meet EPA requirements either way. How well they burn with one as opposed ti without I'm sure depends on the model. For my Intrepid the cat is an extra cost item and not supplied with the purchase of the stove in and of itself. With that said there is a noticeable increase in flow through this stove without the cat as there is less restriction in the combuster. If your draft is on the weaker side maybe no cat is the better option???
 
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Mine's not a flexburn, mine is old technology first gen cat stove.
Last night in the 30's threw about 6 splits in as I went to bed at midnite less than 1/2 box total, all smaller size splits of well dried oak. I didn't touch the stove until almost 9AM this morning. Stove was still very warm, house was about 70. I opened the top and used my fireplace shovel to move the ashes around and had a nice hot pile of coals. Threw a handful of dry kindling on it and a couple of small splits. Lit right off and away we go.
I do have to watch the flue temps and STT as I can get it waaay too hot in the house if I don't cut the air back. Yes, I know I'm "burning dirty", and yes I know it's not as efficient. But it is so simple to burn like this a child could do it with no anxiety about cat temps.

One thing that remains consistent with VC stove is cat or no cat I can still induce a back puff. Tempting to place the full kettle or a weight on the griddle to help keep the smoke in the stove when it does it.

It seems to be a trade off between the heat going up the flue or the heat being burned in the cat. The heat in the cat never reaches the house as the house is always hotter if I burn without the cat. Even when cat temps go to 1500-1600 the house doesn't get any warmer and STT don't go up.
 
For the record, and I have said this before, in my case the cat is only in my stove to keep the chimney cleaner. I too have never seen a difference in house temperatures with cat or without.
My stove just operates differently with/without it.
 
Mine's not a flexburn, mine is old technology first gen cat stove.
Last night in the 30's threw about 6 splits in as I went to bed at midnite less than 1/2 box total, all smaller size splits of well dried oak. I didn't touch the stove until almost 9AM this morning. Stove was still very warm, house was about 70. I opened the top and used my fireplace shovel to move the ashes around and had a nice hot pile of coals. Threw a handful of dry kindling on it and a couple of small splits. Lit right off and away we go.
I do have to watch the flue temps and STT as I can get it waaay too hot in the house if I don't cut the air back. Yes, I know I'm "burning dirty", and yes I know it's not as efficient. But it is so simple to burn like this a child could do it with no anxiety about cat temps.

One thing that remains consistent with VC stove is cat or no cat I can still induce a back puff. Tempting to place the full kettle or a weight on the griddle to help keep the smoke in the stove when it does it.

It seems to be a trade off between the heat going up the flue or the heat being burned in the cat. The heat in the cat never reaches the house as the house is always hotter if I burn without the cat. Even when cat temps go to 1500-1600 the house doesn't get any warmer and STT don't go up.
I had an Encore 0028 and put a pot on the griddle, but the backpuffs were strong enough to lift the pot unless it was completely full of water.
 
At that point I wonder is it not better to uninstall the cat and close the bypass, letting the fire come further forward
 
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I had an Encore 0028 and put a pot on the griddle, but the backpuffs were strong enough to lift the pot unless it was completely full of water.
The Griddle gaskets take a beating. If they are even a little worn they don't seal real well even with wieght on it.
 
The Griddle gaskets take a beating. If they are even a little worn they don't seal real well even with wieght on it.
Yep, I was going through two griddle gaskets a year with that stove just to keep a good seal.
 
The top load is great but you really have to be careful when loading around the gasket. I've always used the steel mesh covered gasket.

As for house temperatures I actually find my house much warmer without running the cat. When running the cat it's hard to get higher house temps without the cat going crazy and then you find yourself constantly monitoring it. I can load it how I want and walk away, I can sit and watch TV without having to get up and walk into the other room to check the stove. I can toss wood in on the way to bed and go right to sleep with no constant thoughts about the cat overheating.

I don't buy wood, I have my own woods to cut from. I don't pay someone to clean my chimney, I do it myself. That makes a lot of difference in my way of burning.
 
At that point I wonder is it not better to uninstall the cat and close the bypass, letting the fire come further forward
Interesting question, I've never tried it. My cat installs from the back through a panel.
 
I dont know that Im sending alot of heat up my chimney without a cat in. Maybe I am? What would be the proof?
Good question, and probably a difficult thing to prove, with the tools any of us have at home. I'd think the best bet would be to compare stove top temperature to flue probe temperature over the course of several burns, with a working cat versus a removed cat in the same setup.

I'd like to say flue temperature versus burn time, but then you get into that hairy area of trying to define "burn time". Stove top temperature is a reasonable indicator of how much heat you're putting into the room, and flue temp is obviously a very good measure of what you're sending up the flue. The difference is some indicator of efficiency.
 
I don't have a flue probe, I installed DW extendable pipe and didn't want to drill it. What I do have is a magnetic thermometer on the flue adapter that goes straight up and converts from oval to 8" round. Right now without the cat in STT is about 150* higher than the flue temp, right now 550STT flue therm 400. Stays the same difference as the STT temp drops.
I looked at some of @arnermd graphs and his STT to griddle will be about the same difference even with the cat pretty hot. I didn't figure he'd look at this thread so I tagged him, maybe he'll comment.
 
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Right now without the cat in STT is about 150* higher than the flue temp, right now 550STT flue therm 400. Stays the same difference as the STT temp drops.
I looked at some of @arnermd graphs and his STT to griddle will be about the same difference even with the cat pretty hot.
400F on the surface of single wall sounds hot, but maybe that's just because you have the thermometer mounted down low close to the stove collar.

For comparison, I have a surface thermometer on single wall pipe about 18" above collar one of my cat stoves, and it never runs above 200F while cruising on any medium or low setting, likely including 550F STT. I say "likely," because the stove has a convective top, so I can't really measure stove top temp without removing the top, and it's too hot to do that now. The combustor probe is running around 750F right now, and that's right under the top, and flue surface is 175F. That seems like it must be much more efficient than your 550F/400F ratio.
 
For the record, and I have said this before, in my case the cat is only in my stove to keep the chimney cleaner. I too have never seen a difference in house temperatures with cat or without.
My stove just operates differently with/without it.

So the catalyst actually doesn't add any additional heat.. maybe a little if the cat temp is high you may get some off the stovepipe and back of the stove, but nothing substantial. What the cat does and does well is help you burn clean at low low air settings and allowing you to stretch your BTUs out over an extended period of time.

I feel that the more efficient way is with the bypass closed and a lower aire setting VS a higher air setting and the bypass open and the heat just running right up the stovepipe.

With the bypass closed and the lower air setting more heat is being transferred from box to room. The hot air needs to work its way through the stove.. yes your not feeling the stove hotter.. cat vs non cat.. but your transferring more BTUs over the course of the load
 
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So the catalyst actually doesn't add any additional heat.. maybe a little if the cat temp is high you may get some off the stovepipe and back of the stove, but nothing substantial.
I have trouble believing this. We have all seen our stovepipe probe temps drop from 700F in bypass to 300F with cat engaged, at the same burn rate. We can argue about the BTU content of all that hot air going up the pipe, in fact @ABMax24 can probably calculate for us. But no matter how you slice it, lower exhaust temperature at a given burn rate directly translates to more heat coming off the stove into your house. Simple Newton's Law of Conservation stuff, here.
 
I have trouble believing this. We have all seen our stovepipe probe temps drop from 700F in bypass to 300F with cat engaged, at the same burn rate. We can argue about the BTU content of all that hot air going up the pipe, in fact @ABMax24 can probably calculate for us. But no matter how you slice it, lower exhaust temperature at a given burn rate directly translates to more heat coming off the stove into your house. Simple Newton's Law of Conservation stuff, here.

So if im reading this correctly.. your agreeing with me..