Location for thermometer on Buck 91

How are you mounting the thermometer to the glass on the door?

I'd suggest up by the cat probe thermometer. Stove is single wall in that location. You can pull the probe and see the catalyst when it's glowing.

You're welcome. I used my infrared thermometer to find the hottest spot above the door and right next to the probe was it, so that's where my magnetic thermometer went. I'm not looking for absolute accuracy with that thing, just a relatively close number to compare to previous burns. Seems to work fine for that purpose.

Mine usually reads between 1100-1400. It will get in to the 1500-1700 range if it's really cranking. Like the magnetic thermometers, I'm not sure if there is a great deal of accuracy in those mechanical probe types. Is your cat glowing the entire time when you are showing the 1700-1800 temps? I would expect it to be if that probe is accurate.

On the Model 80, there is a channel iron welded to the outside of the firebox (but inside the outer shroud, so it's not normally visible), running diagonally from the bottom front corner up to the angle iron that runs behind the cat housing. You can see the holes in the angle iron that feed secondary air to the cat if you shine a light up behind the cat housing (kind of difficult to see with the flame shield installed). There is no adjustment to these secondary air supplies.

The cat probe is all you really need. Just follow the guidelines in the owner's manual and keep the cat within the temps listed in the FAQ on Buck's web site, and you shouldn't have any problems. As you mentioned, there's not a good place for an external thermometer anyway.

For the manual:
BURN RATES
A. Low Burn Rate: Set primary air controls (both) almost closed - leave open about 1/8". Set the rheostat
for fan control between the low to medium speed. This burn rate is the most desired and most efficient,
but can only be achieved after a fire has been established and burning on its own controlled air. Close
the bypass damper (push in).

B. Medium-Low Burn Rate: Partially close primary air controls (push halfway in). Close the bypass
damper (push in). Set the rheostat for the fan control halfway between low and high.

C. Medium-High Burn Rate: Set the primary air controls almost fully open. Close the bypass damper.
Set the rheostat for the fan control between the medium position and the high position.

D. High Burn Rate: Set primary air controls wide open. Have the damper closed. Set the rheostat for the
fan control all the way on high. USE CAUTION! Close shotgun air control after 5 minutes.

E. Wood Loading: During refueling, open (pull out) the bypass damper to allow smoke in the firebox to
escape - wait a few seconds, slowly add wood. Immediately close door and bypass damper. Open
primary air control wide open for 2 minutes to charge the wood. After most of the wood has burned and
if you are not planning on reloading immediately, it may be necessary to open damper bypass, then the
door, and rake the wood and coals into a pile near the front center of the firebox. (Be certain wood
chunks are pulled out of the rear corners.) Close the door and the damper bypass. This step will assure
continued combustion and thorough burning of the wood.

From the Web Site FAQ:
CATALYTIC COMBUSTOR TEMPERATURES

COMBUSTOR TEMPERATURES CAN BECOME EXTREMELY HOT DURING OPERATION. TEMPERATURES ABOVE 1800° F. WILL DAMAGE THE CATALYST. TEMPERATURES BETWEEN 1400°F. AND 1600° F. ARE NORMAL, BUT TEMPERATURES BETWEEN 1200° F. AND 1400° F. ARE RECOMMENDED.

davidmc said:

just curious....what does your cat read during main burn.

If I put 3 sticks of wood in mine stays on 1700 to 1800. I took your suggestion and tried different settings and even closed and when it gets going that is where it stays.

I Wonder if there is any adjustment on the secondary air?

Click to expand...

1700-1800 is too high for the cat. You don't want to damage it since it's expensive to replace, >$300.

Did you close both air controls?

David, what is your chimney length? If it is over 20', you might be getting more draft than necessary and getting too much air into the stove as a result.

Also, you mentioned "three sticks" in the stove. What kind of wood? What size are these pieces of wood? Smaller sizes and super dry (like kiln dried lumber scraps) will give up their volatile compounds more quickly than larger (and less dry) ones. Try using larger pieces than you've used in the past to slow down the burn rate.

I was just thinking about your bypass damper as well. On mine, if you push it in too hard, it seems to climb up a ramp at the end of the travel, which could allow some air to get around it. Try this: With the stove really cranking, cat probe removed and damper open, look through the cat probe hole. You should be able to see flames shooting up into the flue through the damper hole. Slide the damper rod in until it just touches the stop. If you can still see flames, you've got a damper alignment problem. The manual talks about the damper possibly getting knocked out of it's track and how to fix it (IIRC).