Question regarding letting a catalytic stove burn out...

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Mustard Tiger

New Member
Feb 13, 2024
32
PNW
Had a Sirocco 30.2 installed a couple days ago. I've been reading through the manual and reading older threads on this forum. Of course you're not supposed to close the damper until the temp is in the active zone the thermometer. I've also read on older forums that it could even damage the catalyst to run the stove with the damper closed before reading the active zone.

My question is, so what happens when you are int he active zone, close the damper and then let the fire burn over time and are unable to tend to it because your away from the home and the temp eventually drops back down below the active zone? Will letting the fire burn out over time with the damper closed cause any damage to the stove over time?
 
Will letting the fire burn out over time with the damper closed cause any damage to the stove over time?

Nope, the cat will eventually go out of active mode when it can no longer sustain temperatures hot enough for reburn. At that point and time enough of the particulates in the wood is gone so you are left with pure heat from coals going through the cat.
 
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Nope, the cat will eventually go out of active mode when it can no longer sustain temperatures hot enough for reburn. At that point and time enough of the particulates in the wood is gone so you are left with pure heat from coals going through the cat.
Awesome. Thank you for this.
 
Of course you're not supposed to close the damper until the temp is in the active zone the thermometer
Also not entirely true. At least not if you have a flue thermometer.
I do cold starts with the thermostat wide open and the bypass open, and when the flue temperature reaches 800-900F, I close the bypass and dial the thermostat down. That is with a double-walled flue and a probe thermometer.
By then the fire is already well established, just the cat probe hasn't caught up yet. That directs quite hot gases through the cat. At that temperature, the gases are sure to react on the cat surface, heating it up even faster. And within 15 minutes or so the cat probe has finally caught up and shows active.
 
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On cold starts, I close my bypass when the cat probe is near the letter "A" in "Active", and they light off every time. Basically, as soon as there's good consistent flame and the front of the load is mostly charred (not even completely), I close the bypass. The cat will usually start glowing within 30 seconds, indicating it's over 1000°F, even though that stupid slow cat probe is still reading something equivalent to 200°F.

All of these cat probes suffer from the same problem on cold starts, they tell you the temperature the cat was at 5 minutes ago, not now. And 5 minutes is a very long time, when ramping up to 1500°F from a cold start over the course of 10 minutes.
 
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