Why with a catalytic you can get it really really “hot” but with secondary burn wood burning stove. You can’t really get it hot… is it because catalytic is better
secondary wood burning stove vs catalytic wood burning stove
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I don't really understand the question. The cat gets very hot but overall the stove does not. In general straight cat stoves actually run a little cooler overall
The internal firebox temperature of a non-cat is typically over 1000º, iow very hot in order to achieve secondary combustion.
stoveliker
Minister of Fire
A cat stove CAN get similarly hot as a non-cat.
For the non-cat it's needed to be sufficiently hot for secondary combustion as begreen says (otherwise you may gunk up your chimney).
A non-cat can in principle have the firebox at a lower temperature (even no flame at all), and have the cat become hot while combusting the smoke.
The cat itself is much smaller than a full firebox, so then less heat is produced in total, leading to a lower heat output of the cat stove - when it's run low.
I think your question may be related to the temperature readings? Not hotter than 800 or so on a noncat (stove top) otherwise it gets to overfiring regime, whereas a cat thermometer can go to 1400 or so.
For the non-cat it's needed to be sufficiently hot for secondary combustion as begreen says (otherwise you may gunk up your chimney).
A non-cat can in principle have the firebox at a lower temperature (even no flame at all), and have the cat become hot while combusting the smoke.
The cat itself is much smaller than a full firebox, so then less heat is produced in total, leading to a lower heat output of the cat stove - when it's run low.
I think your question may be related to the temperature readings? Not hotter than 800 or so on a noncat (stove top) otherwise it gets to overfiring regime, whereas a cat thermometer can go to 1400 or so.
It's just a heat inside the catalyst, because the meshes are very thin, and because there are metals that also allow smoke to burn. If it were a real heat, of air, the flue temperature would be very high and this absolutely does not happen. The top of my stove has a lower thickness, compared to the rest, and reaches temperatures much 30 percent higher at least
vap0rtranz
Member
When I engage my cat, the stovepipe temp drops.
I think that's a big point that the OP might be missing. Less heat going up the chimney = less wasted wood. The cat isn't reducing the temp, I'm not shutting down the stoves air, so where did the heat that would normally go up the chimney go? It's not magic. It's physics. That heat energy stayed inside the stove. And that's where I want it.
My stovepipe temp drops by 40-60F when I engage the cat and my stove temp goes up. I run a double walled stovepipe and soapstone stove so the temperature change might seem low for others running single-walled and steel stoves. Point is I don't need to run my stove hot.
I think that's a big point that the OP might be missing. Less heat going up the chimney = less wasted wood. The cat isn't reducing the temp, I'm not shutting down the stoves air, so where did the heat that would normally go up the chimney go? It's not magic. It's physics. That heat energy stayed inside the stove. And that's where I want it.
My stovepipe temp drops by 40-60F when I engage the cat and my stove temp goes up. I run a double walled stovepipe and soapstone stove so the temperature change might seem low for others running single-walled and steel stoves. Point is I don't need to run my stove hot.
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stoveliker
Minister of Fire
vap0rtranz
Member
Figured that's what you meant.
And that's how my cat runs. Stovetop temp runs between 400-500F and there only be red hot coals, or just small secondary blue flames popping in and out.
It keeps the house warm without turning me into a sweat bomb when near the hearth.
I remember my Grandpop's homemade sauna stove. It was a beast. Every Christmas the family would be sweating in Grandpop's living room while opening presents. He didn't mean for it to be a sauna but that was the only way to heat his house.
the flue temperature drops because the draft is reduced with cat active ( I'm not against cat stove, on the contrary )
No the draft is not reduced by an active cat at all. But an active cat allows for the air to be shut down further while still maintaining a clean burn. That means cooler firebox and less air up the chimney leading to lower exhaust temps. But also lower overall temps as well.
stoveliker
Minister of Fire
I think that statement ("not at all") is too general.
I do think in most stoves engaging the cat increases the impedance of the exhaust gas flow (and thus decreases the speed/flow). It certainly does in your and my cat stove (straight up the pipe thru the bypass vs thru the many small holes in the cat).
But I think that for many cat stoves, engaging the cat re-routes the hot exhaust gas flow in such a way that more heat is shed into the room. And THUS the exhaust gas flow will be cooler because the efficiency (heat into the room vs heat up the flue) goes up due to the different flow path. This is also certainly the case for your and my cat stove.
Oh absolutely engaging the cat increases impedence. But that isn't reducing draft if anything it would make the draft measurement go up because of the increased restriction. But none of that has anything to do with active cat or not
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stoveliker
Minister of Fire
I see what you mean.
I'd still make the case that engaging the cat does decrease the exhaust temp, and thus will decrease the draft (pressure difference) leading to lower flow in addition to the lower flow from the higher impedance.
I'd still make the case that engaging the cat does decrease the exhaust temp, and thus will decrease the draft (pressure difference) leading to lower flow in addition to the lower flow from the higher impedance.
Absolutely reduced flue gas temps will reduce draft. And simply engaging the cat will reduce temps slightly but not much without also reducing intake air.
It does take a hot stove to see noticeable secondary burn from the top burn tubes. But once the stove is cruising, the main air is almost off, the secondary burn (northern lights) is almost not seen. But the stove, after a cold start smoke, has no visible smoke out of the chimney. Is it as clean as a cat stove?
With my non cat, I do like the fact that i'm not dealing with a plugged cat and buying a new ones. They're not cheap.
With my non cat, I do like the fact that i'm not dealing with a plugged cat and buying a new ones. They're not cheap.
Isaac Carlson
Minister of Fire
a local guy bought a cat stove last fall and it is a different critter. He keeps leaving the bypass open to get flames and his heat goes up the chimney. I have tried explaining how to run it, but he doesn't seem to get it. The cat was completely plugged a couple weeks ago, so I cleaned it for him. I think he would have been better off with a secondary stove.
This is true for many stoves and perhaps in particular for cat stoves. Poor maintenance is common for most wood stoves according to the survey done in Oregon. For many, the cost of a cat replacement is not just the part, but the dealer markup and service call. When that adds up to $500, many are likely to defer. Most stove owners are not wood stove enthusiasts.
Isaac Carlson
Minister of Fire
Yep. I think he got it to make the house look nice more than anything else. He uses the heck out of it, but doesn't understand how it works.
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