Let the big cat eat! Buck 91 up and running. Advice, tricks and tips welcome...

This may be the key. Wife was in town, so she loaded the stove. There were some split shapes left (which crumbled when she raked them to the front/middle. They were probably giving off blue flame, but she couldn't recall as she had also put a couple of splits on to bring up the temp for the reload. With the bypass open, probe temp went to 1140. She loaded up, got some flame in the middle with the shotgun air, and was off to the races. Probe got up around 1500, stove to 500, and then leveled off.
The times lately when I had trouble getting to cat to take off, I had most of the coals in the middle, big wood on the sides. I loaded a couple small ones in the middle to get that area hot quickly, but put some bigger splits on the top of that. I gave it air, figuring that the heat from the flames would come out the back of the 16" splits and heat the cat area, but apparently that doesn't work. This AM I had coals in the middle but just small stuff on top, and got big flame coming up to the shield. Closed the bypass and the cat took off nicely to over 1000. Cut the air back, turned on the blower, and cat temp didn't fall much. I'll keep starting this way with big flame able to come out the top of the load unrestricted. Hope I didn't buy a cat for nothing but I'll put it in, and do expect to see improved performance. I like to have a backup cat around anyway...

OK, I put the new combustor in on Thursday...yep, the old one was tired. Glad I didn't spend my money unnecessarily. I'm still going by the book and engaging when it's close to 700 on the probe and wow, she lights off pretty quick and no worries about a stall. I restart the blower at about 800, and see little drop in the probe temp. I'm seeing no smoke at about 900, vs. 1200 with the old cat. Neighbors will be happy. I expect to get more heat as well, now that more smoke is being burned. I replaced the ash pan gasket several weeks back, hoping to stem the air coming up through the ash dump lid, but it slowly developed a similar gap where the ends of the rope gasket meet. I think with repeated contact with the pan housing, the strands at the rope ends loosen up. I ran a couple ideas by the folks at Buck, one being to fill in the gap with silicone. They emailed back almost immediately, saying 'Yes, that will help.' So far, customer support from Buck has been outstanding with quick email responses and informative answers to my questions. Anyway, I ended up using gasket cement to glue a small piece of rope into the gap. We'll see how long that holds up... I might also try replacing the rope with a flat gasket at some point. Anyway, the results are outstanding! The left side of the box still burns a little faster than the right but there are some decent chunks remaining on the left after a 12-hr. burn. Before, there was nothing but ash over there. The load is burning more in the middle of the box instead of on the left with too much flame. The result has been a longer burn with good heat output after 12 hrs. 600 probe, 250 stove top and house temp a good bit higher. I haven't had to burn any sacrificial splits to get stove temp back up for the reload, just pull some chunks/split shapes forward and open the air a bit to get up around 700, then reload. I'm no longer concerned about the cat temp going high now that I've got better control of the air. I may adjust the air slider plates up to allow me to cut the air even more, if I desire.

I recommend that all Buck owners check for a gap at the ends of the ash pan gasket if they want to be able to run their stove slower. It's made a huge difference in my case. Not sure if other Buck models have a similar ash pan gasket?

I just saw that the door latch pawl(?) is too far back, and partially hitting the plate steel...easy fix by loosening the set screws (I mistakenly said it had a roll pin earlier.) Actually, one screw is missing and you can see the edge of its hole in the pic.


Now that I'm finally getting the stove set up right, I'm sure it's going to do everything I ask of it and it'll be much easier to run, to boot. I'm one happy camper, and lovin' this stove more all the time!

A revised burn-time report is forthcoming.

Good to hear you are getting the beast tamed and tuned. I have never even had my ash drawer out so I will have to take a look at that. I don't think you said but how hot is your cat running now. Are you able to get it to the 1500 - 1800 range pretty easily now? Also what kind of cat did you get and where?

Yeah, I'm really pleased with the way it's going.
Like I said, there is still a little air coming in at the ash drop but nowhere near what it was. I cleaned the glass last night and only had a little brown haze in the lower corners this AM. Contrast that to the previous clean left-side glass due to the ash pan leak inferno, and gunked-up lower right glass. Now that I'm getting a longer burn with stronger, more even heat output, I don't have to cram the box full. I don't have to push the coals to the back to make room for wood, I just heap 'em up in the middle, N-S. Then I can load the 16" splits further back, away from the glass. That may help keep it cleaner, I don't know. Just sealing the ash pan leak is getting more air coming in through the air wash, I'm sure. We had 69* in the furnace thermostat room, next to the stove room, this AM. No, it wasn't too cold last night, around 40, but the wind was pretty strong.
I never had a problem getting high cat temps. In fact, I was more worried about it going too high. I don't think that's going to be an issue any more, with more control over the air. The problem was getting the cat to take off with a new load. And even with the cat glowing away there was still some smoke out of the stack. Besides a tired cat, that have been partly due to too much air (cool ash drop air at that) moving the smoke too quickly through the cat and not giving it the time it needed. Hard to tell what actually happened since I made two changes at once (new cat, fixed air leak.) Highest cat temp I've seen with these changes has been 1200. Waiting for more recorded daytime readings to come in from further into the burn...
I may keep burning sacrificial splits to raise the stove temp if I need to. That way I can get big flame and radiation against the walls of the box. Once you have 'er loaded up, radiation against the sides is limited. This AM, MIL had opened up the air a bit when she got up, and I was ready to load up as the probe was already around 700. By the time I had 800, cat was glowing and no smoke.
The replacement cat is OE, Applied Ceramics from firecatcombustors.com, the site that AC directs you to. I will be starting a thread about that soon.
Yep, I'm stoked about the situation now. I think I'll be able to get 12 hrs. of good heat on lesser fuel, like soft Maple. This would sure take the pressure off since I should be able to dry quite a bit of that this summer. Hopefully I can save the slower-drying high output woods for those colder-than-average nights. Once I get far enough ahead, it'll be a moot point and I'll burn whatever the hell I want.
Gonna get cool this weekend; Might have to stuff 'er to the gills with Hickory and BL, and go for the Long March burn.

just installed a used Buck 91 .. barely getting 1,000f degrees max after getting box good and hot before engaging cat. just not putting out enough heat

time for a new cat? there's all sorts of instructions on the web, on how to clean your old cat... is it worth cleaning or just order a new one and be done?

Where are you measuring that temp at?

at the cat with thermometer next to damper handle. did get 91 up to 1,500f last night.. today could barely get it pass 800f ... thinking intake air dump is clogged inside.

took the cat off yesterday and made sure it nothing was plugging it up. a few cracks showing.