Regency i2500 Catalytic combustor question

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New Member
Feb 27, 2022
We recently had a Regency i2500 professionally installed and I have some questions about the catalytic combustor that I was hoping you all might be able to help me with.

We're in Wisconsin, so all temps are in Fahrenheit, and we're using fully seasoned oak as our fuel source, in case it helps.

In regard to using the catalyst, I understand that the insert probe should be reading at or over 500 degrees (F) before engaging the catalyst. We really need to have a roaring fire for the probe temp to even start to get near 400, so to get it to 500 seems to take a lot of fuel and time to reach. Is this normal?

Now my real question is, once I have a good coal bed, I load the stove fully, and leave the draft fully open to get the probe to read over 500. Once I have it reading 500, and engage the catalyst, it sounds like I want to leave it in that temp area for at least 30 minutes. To do that, I seem to need to keep the insert going at full draft. However, once a half hour is up, do I need to keep the draft open to maintain those temps, or is the catalyst self sustaining, and I can close the draft a bit and let the temp that the probe is reading fall?


Minister of Fire
Nov 17, 2019
Long Island NY
I don't have your stove but I do have a cat stove.

How long does it take to get to 500 F on a cold start?

Once the cat is engaged, you should be able to keep it engaged without much trouble as it'll generate heat.

How tall is your chimney? (Too much heat exiting because too much draft?)
Are you sure your bypass closed/seals properly (no heat escaping there)?
How do you know your wood is dry enough?

In principle, decreasing the air after the cat is engaged should result in a hotter cat because decreasing air will make more smoke - which is the fuel for the cat.


Dec 16, 2021
From a completely cold start, I think it's taken me up to 20 minutes to get the cat probe up to temperature, but usually it's not that long (it's a soapstone stove, so it soaks up the heat). I'd say if it's been 14 hours or less since the last reload, it will take 5 - 15 minutes to go from no fire to cat probe at 500. Check your manual, but I don't think you'd normally want to run with the air all the way open and the cat engaged - I close mine down halfway when I engage the cat. Depending on stovetop and room temps, I might leave it that way for 5 - 15 minutes (I think of this is running on 'high') before closing it down to 25% ('medium'), and for overnights I'll close it all the way down. The cat is self-sustaining with enough smoke, and it's generally more efficient at lower air intake settings.
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Congratulations on your purchase!

I own the Regency i1500, so I assume you are using the same Regency branded digital probe thermometer included in my installation.

This winter, I am burning both kiln-dried hardwood and 3-4 year seasoned oak.
I usually fill the firebox box 1/4 full on initial start-up. In my experience, from a top-down burn, it takes 5 - 15 minutes to achieve a probe temp of 500 degrees. I engage the catalyst at 600 or so and cut the air intake in half. From this 1/4 full load, the probe temperature reaches about 1000 degrees and drops somewhat quickly to 9- 700 degrees.

Once I have a good coal bed and the fan turns on, I load the stove fully and leave the draft wide open. The stove warms fast, with the probe temp reaching 500 degrees in five-ten minutes. Once the probe hits the temperature, I engage the catalyst and cut the air in half. Over the next twenty or thirty minutes, I slowly turn the air all the way down.

At this point in the process, on average, the probe temperature won’t fall below 500 degrees for three hours, with the high temperature being 1400.

Did you test the oak’s moisture?
Is it below 20 percent?

I know it seems like those are usually the first questions asked on this forum if a user is having an issue with their stove. The reasoning is valid. It’s easy to test, easy to fix and is usually the cause of most issues.