When to re-engage cat after reload

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Garbanzo62

Minister of Fire
Aug 25, 2022
629
Connecticut
My insert instructions state to wait until the probe temp gets to 500 degrees before engaging the cat. I normally start to shut the damper down when the probe is between 600 and 700 degrees. The probe temp falls as soon as I start cutting back on the air and will usually drop below that 500 degree level even with the secondaries going pretty good. My question is, if I want to add wood a bit later, do I need to get that probe up above 500 before re-engaging the cat (I disengage befor openning the door). I do after the overnight burns because the probe temp is usually below 200, but I wasn't sure about when I just want to add some wood to what is going already.
 
I think the probe in the instructions is the catalyst thermometer, whereas you are talking about the flue probe?

The cat is not active below 500 F, but flue temps are regularly below 300 F for me.
 
I think the probe in the instructions is the catalyst thermometer, whereas you are talking about the flue probe?

The cat is not active below 500 F, but flue temps are regularly below 300 F for me.
Well the stove came with the probe. Not 100% sure where it is, but I believe it is a flue probe above the cat. I would think the heat from the cat would keep it above 500
 
Not for my stove. My probe in the flue is often below 300. My cat probe is not.
 
Well the stove came with the probe. Not 100% sure where it is, but I believe it is a flue probe above the cat. I would think the heat from the cat would keep it above 500
Where is the probe located? Do you mean your stove came with a catalyst probe? Is so, does it have temperature numbers or just an Active Zone marking.

moved thread to Regency forum
 
From what I can gather from the manual, the probe goes into the flue adaptor. It appears that the cat sits right underneath that. The cat on this model slides on tracks to be engaged. Effectively you slide the cat to be under the flue adaptor which causes the gases to be routed through the cat. The digital readout is in degrees.
 
When the cat is active, I would expect the temp to read at 500º or higher, except in the late stage of the burn when there is no more smoke for the cat to chew on. There is no smoke generated during the coals-only stage.

There have only been a few reports for this stove so far. Your observations are helpful. I am uncertain whether the cat will be very active if most of the secondary combustion has burned up the volatiles before the cat. That may be what you are seeing. You might want to try varying routines, maybe batch loading with full loads instead of adding a bit at a time, to see if that keeps the cat active over a longer period of time.
 
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When reloading you need to get enough wood burning to feed the cat, but I might close the bypass before the cat probe is up to 500, then feed moderate flame heat to get and keep the cat burning, until smoke starts feeding it. Not sure of the design of your stove, but you need to make sure that flames don't reach the face of the cat, or damage could result. Your procedure may differ from mine, since you have a hybrid stove and mine is a straight cat stove.
Cat temp will rise rapidly when I close the bypass and feed it some flame heat, then once enough wood is burning to feed the cat I cut the air in several steps. Then I might go for a cat-only burn with no flame, or I might leave a bit of gentle flame going.
Dense woods will require longer burn-in time to start gassing/smoking well..
 
I notice that when I first engage the cat the temp rises rather quickly, but as I shut down the air, it begins to drop. Generally leveling off in the 375 - 400 range
 
To me that indicates that either your cat is not working properly, or you are not measuring the cat temp but instead the flue temp.

When you shut down the air, the cat temp should rise as it gets to eat more smoke.

When you shut down the air (after the cat reaching 500 F), and you look half an hour later outside at the chimney, is there smoke?
 
I notice that when I first engage the cat the temp rises rather quickly, but as I shut down the air, it begins to drop. Generally leveling off in the 375 - 400 range
To me that indicates that either your cat is not working properly, or you are not measuring the cat temp but instead the flue temp.
When you shut down the air, the cat temp should rise as it gets to eat more smoke.
Yeah, once I close the bypass, cat temp is over 1000 within a few minutes. If I cut air to my low setting and cat temp starts dropping, then I haven't got enough wood gassing. I either open the air, or I might need to get some flame going again--that raises cat temp, even if wood smoke by itself won't raise it.
Has to be 500 or above to sustain light-off running on just smoke.
 
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