Buck 91 cracks in metal!?

[tebenhoh]

Newbie here. [Wave]
Buck 91 insert was in a home we purchased 2yrs ago, and we’ve used it the past 2 seasons. This forum taught us everything we thought we needed to know about using and maintaining a catalyst wood stove - never had one or used one before we bought the house. Seriously, this site is/was a godsend.
We were meticulous about dry wood, opening/closing damper, correct temperatures, etc after reading posts here.
This Spring we decided to do some maintenance since we have no idea about the stoves history or previous use - the house was abandoned for almost 3yrs, and PO skipped state while filing bankruptcy.
Buck actually updated their manual for the 91 and it shows the catalyst location and replacement, so I dug in only to find - see photos!
NO lower cat shield.
NO catalyst.
Catalyst housing held by 2 nuts - there’s 8 bolts.
(I have more photos.)
We’ve purchased the catalyst and gaskets, and are about to order the other necessary parts - cat housing, brass nuts, lower shield, etc. I sent these photos to a dealer who said they didn’t look too bad. I sent them to Buck who said maybe 2 seasons. The photos are looking through the door and up at the top of the firebox where the cat housing usually is, the bolts secure the housing to the top of the stove. There are cracks at 6 of the bolts I believe, and “bad?” cracks at the two rearmost corners.
Please flood us with info and options; is the stove usable, is it trashed, can it be repaired, should it be repaired???
Thanks so much in advance, and again for the knowledge gained here to even know how to get this far!

 

[begreen]

Welcome and good work with the dry wood. The cracks may be repairable. Is there a good welder in the area?

 

[tebenhoh]

Thank you, for the welcome and the compliment!
We do, and I wondered whether welding could be an option. I was hoping to avoid moving the stove. It is, however, a better option than buying a new stove! Is it a ridiculous idea to even think of having it done where it sits, in the house? We have an outside door, and windows, in the room for ventilation. To start the conversation with the welders, would a smaller portable wire feed welder be sufficient, or are we talking the big guns - 240v or 3phase?
Also, I purchased extreme heat JBWeld (2400deg) to fix a stripped screw in the door which holds a plate that sandwiches the glass and it’s gasket. I’m assuming that may only be temporary at best, or useless, for the cracks?

 

[tebenhoh]

I got a trophy, first post!

 

[Highbeam]

Thank you, for the welcome and the compliment!
We do, and I wondered whether welding could be an option. I was hoping to avoid moving the stove. It is, however, a better option than buying a new stove! Is it a ridiculous idea to even think of having it done where it sits, in the house? We have an outside door, and windows, in the room for ventilation. To start the conversation with the welders, would a smaller portable wire feed welder be sufficient, or are we talking the big guns - 240v or 3phase?
Also, I purchased extreme heat JBWeld (2400deg) to fix a stripped screw in the door which holds a plate that sandwiches the glass and it’s gasket. I’m assuming that may only be temporary at best, or useless, for the cracks?

The welder will know what to do and most have the power source on their truck. That metal is thick enough to stick weld but wire feed machines are certainly available that can do it too. Comes down to the professional’s preference. The chimney will draft most of the welding fumes away. Anything that spills out is no big deal. He will need to grind the weld smooth since you need to bolt something in place so have that thing there for him to test fit.

I would expect him to weld it in place. Be expecting him to be dirty. Warn him to protect the floors from sparks. Welders are good at welding in dirty environments, not so much your living room.

 

[Corey]

I guess it's going to depend on what type / level of repair you want.

If you want some guy to come out with a truck and weld 'upside down' inside your stove (believe these cracks are on the 'roof' of the firebox, yes?) Then yeah, he can probably slap some weld beads on there and keep the cracks from coming back for a year or two.

If you want someone to go in and fully grind out the cracks and re-weld so ALL the cracks are gone - that's likely going to need to be done in a shop with better access to the problem area. That might keep the cracks away for another "however old the stove is now". (You've burned it two seasons, sat empty for 3 seasons, previous owner burned some..."?)

But the real problem is all those sharp/square corners. If you want the cracks to go away and stay away, those need to be dealt with in some manner. That is likely a pretty big undertaking and likely beyond just a general welder.

Another option would be to keep an eye on the cracks and burn for another season - assuming they aren't making any huge issues with gas bypassing the cat. It might be that all the stress has essentially 'relieved' and the cracks aren't actively growing. If the stove works fine and the cracks aren't growing, then they may not be a big issue.

 

[tebenhoh]

The welder will know what to do and most have the power source on their truck. That metal is thick enough to stick weld but wire feed machines are certainly available that can do it too. Comes down to the professional’s preference. The chimney will draft most of the welding fumes away. Anything that spills out is no big deal. He will need to grind the weld smooth since you need to bolt something in place so have that thing there for him to test fit.

I would expect him to weld it in place. Be expecting him to be dirty. Warn him to protect the floors from sparks. Welders are good at welding in dirty environments, not so much your living room.

Highbeam: Thanks for the welder/welding info. That gives me a clearer idea of what’s necessary. And I understand the dirty part; floors are ceramic tile and the hearth is stone, so we have a little bit of built in protection.

 

[tebenhoh]

Thanks Corey
The cracks are at the top of the firebox where the cat housing mounts, but it’s not the top of the stove. This is why I asked, and why I appreciate the posts with options and information - I didn’t really know which would be better, but from my limited welding experience I assumed to do it right we’d have to pull the stove out.

All I know from hearsay in town is that the PO burned a lot and kept the house very warm. What I don’t know is how hot he burned, what he burned, or how long it was used without the catalyst or lower cat shield or housing gasket (besides our last two seasons, and we kept temps in check). My guess is the stove was overheated, possibly a lotunless those cracks are normal with age? But then the house sat empty with no heating/cooling - maybe we stressed the metal when we first fired it - who knows?

I like the idea of operating the stove normally and watching what the cracks do. We haven’t burned with a catalyst yet, (installing one and a new housing once we figure out the crack issue), so gasses bypassing will be a new learning experience. The cracks will essentially be sandwiched between a gasket and the cat housing, and protected (from flames, not heat) to a point by a shield directly under the cat housing.

What is interesting is how well the stove ran without a catalyst. We’d even go outside and watch for dark smoke out the chimney, and we never could see any by daylight. It heats great! We never got that full all night burn, but there were always plenty of coals to relight. We did have it inspected, when we bought it and again this Spring, and both guys said the chimney looked great. I’m still frustrated that the first guy, a Buck dealer recommendation, didn’t know, or didn’t tell us, the cat was missing.

As careful as we are about fire in the house, your suggestion may win out initially, Corey. It’s a good starting point, and easy enough to monitor.

 

[Highbeam]

I honestly wouldn’t expect a mobile welder to want this job. Lots of risk, low reward, and way outside of their normal type of work.

Is the juice worth the squeeze?

Have you considered replacing the stove? The cat and other parts cost you some cash that may or may not be refundable.

 

[tebenhoh]

We’ve considered it may be necessary, yes. The catalyst is the only part we’ve purchased so far, but I could see us getting another Buck if we go that route. We really like this one, and it would make the install simpler. We haven’t budgeted for it, but we’ve considered it. I scrolled through craigslist and marketplace the other day and was surprised what was available.

 

[moresnow]

If you decide to have the stove welded, let us know the results. I have not had much success chasing cracks around the top of a firebox. The material has been super heated. It act's brittle. Preheating, V'ing the cracks, using multiple flavors of stick or mig type welder's didn't make a heck of a lot of difference for me. Poor results. Sketchy penetration and expanding original cracks. With the limited physical access adding to the challenge!
Hope I am wrong but I would anticipate most attempting welding repairs to encounter similar issues. Good luck.

 

[tebenhoh]

Thank you; I’ll post our decision and results either way. Replacing the stove is the best long term solution, it removes all of the maybe’s and variables, and what if’s. It’s actually good to hear the welding may not be successful if only to narrow our options - if we removed it, had it welded, and re-installed it only to find more cracks, I’d sure have wished we’d replaced it!

 

[Bad LP]

I know a couple of welders who could repair that in place but the travel time costs would kill you. The newer welding units are no longer these huge heavy monsters of years past. One fabricator I know does a lot on interior work like custom staircases and his stuff is all suitcase sized.

 

[tebenhoh]

I think if we’re paying travel costs from Maine, it will be for us to visit!
There are two I know of here with mobile setups, would just need to investigate further as to their equipment and quality of work.

 

[tebenhoh]

UPDATE:
New catalyst, and interam gasket.
New catalyst housing and gasket.
New heat shield.
New side glass gaskets.
New door glass gasket, and door gasket.
New door handle.
New rheostat, switch, and thermostat for blower.
All new hardware/fasteners for cat housing, heat shield, and side windows.
And... my best effort at a “poor man’s block off plate” above the stove!
We found the mfg. plate behind the stove with a serial number, and a mfg. date of 4/2005. So it’s a 15yr old stove with who knows what kind of life.

FIRST CATALYST FIRE tonight as I type:
All air wide open to 400f on cat probe, then shut down shotgun ( left slide). Right slide wide open to 600f, then closed bypass damper and all air. Cruising comfortably at 900-1000f on cat probe after 20-30min, with half (or less) as much wood as we ran her without the catalyst.

I can’t thank this forum, and everyone who has ever contributed, (I search a lot!) enough for helping me along the way to efficient wood burning!

Time will tell whether the cracks get worse, or the stove holds up, but we’re locked and loaded for this season! Cheers all.., be well, be safe, and stay warm!

 

[rwhite]

Not sure how sturdy the catalyst housing is. But if it were me, short of pulling the stove and flipping it to weld, I'd take the new housing to a fabricator and have him make a 1/8" or 3/16" metal frame. I would use a solid sheet. Think picture frame. That could be sandwiched between the housing and the stove. Should provide more support to limit expansion and increasing the cracks. Even if I were to weld it I would probably do something similar so I could overlap the crack and provide additional support.

 

[tebenhoh]

I like that idea if the clearance is sufficient, and it wouldn’t disrupt airflow through the catalyst. I’m curious if not having the catalyst housing properly installed over the years has contributed to the cracks?

The housing itself is very sturdy; my best guess is cast iron, and it’s 1/4” thick. And it’s heavy! Holding it in place in the top of the stove with one hand, while threading nuts with washers with the other, is quite a chore.

This is the “old” cat housing.

 

[rwhite]

That housing looks sturdy enough that you wouldn't need anything additional. Also, just a guess but I doubt you'll see much increase in the crack while the housing is in place. I'm guessing that removing the housing in the future is where you'll see an issue. Those cracks go all the way to the edge and the carriage bolt is going to want to spin and increase the crack.

 

[tebenhoh]

Thanks, that’s a good point, and I’ll be careful! A new housing and gasket is back in place currently, with very snug brass nuts (per Buck). I held the housing in place as tightly as possible, and snugged up the nuts until I felt no movement. The old brass nuts crumbled off of the old housing when I removed it, so my hope is it won’t take a lot of cranking to get them off when necessary.

I have not welded, nor added any additional support to the stove, and I did not try to remove/replace the carriage bolts due to the cracks. I’m sure it will take some hammering, and possibly heat, to remove them when the time comes.

The stove is running great on it’s first fire this season; lit yesterday evening, 28f overnight, 72f in the house this morning. I’m happy!

 

[Woody Stover]

I suspect that the cracks are from firing the stove without the shield and cat in place, where flames could directly hit that area. It's hard to tell from the pics how bad it is, but there appears to be some warping around the cat opening as well.
The area will be more protected now but the top of the box is still gonna get pretty hot in any event, even with the blower pulling heat off it.
I wonder if the air coming through the channel in back of the cat (visible in the 5th pic, first post) was burning some of the smoke, like a secondary tube would, and that is why the plume stayed pretty clean. I wondered if that channel was to supply oxygen to the cat, but maybe it IS a secondary of sorts, so that the cat doesn't have to do all the work. The 91 DOES have pretty low emissions..
You can see the cat glowing if you look in at the right angle through the bypass rod hole. You can also look through the top of the door and see the top of the shield illuminated by the glowing cat; That's fun to do sometimes.
Good luck, and let us know how it's holding up, next time you remove the cat.

 

[bholler]

Most of the bucks like yours I work on have some cracking there. Yours is pretty bad but there is no real danger there. Just some lost efficency. I would run it like that until it causes major performance issues or displaces enough you can't get the cat housing in. At that point decide if you want to pull the stove and have it repaired or get a new stove.

 

[tebenhoh]

Woody, I noticed the cat glow last night for the first time, it was reassuring after doing a first ever refurb! You may be correct about the secondary channel. In the same photo #5 above, where you see the plate with the row of holes; we would have flames dancing through those holes and down from the top of the firebox when previously burning without the catalyst, or heat shield - we unknowingly didn’t help the cracks burning like that ourselves. In the newer Buck 91 manual it shows a diagram which suggests the cat exhausts through that channel to the flue.

bholler; I appreciate the input! When I next remove the cat for inspection, could I install 2 housing gaskets to compensate for the warpage if they will compress enough over the carriage bolts to tighten the housing in place? Like you said, we’re going to run it, and keep watch, until safety and/or efficiency is compromised beyond our tolerance level - safety comes first!

 

[bholler]

Woody, I noticed the cat glow last night for the first time, it was reassuring after doing a first ever refurb! You may be correct about the secondary channel. In the same photo #5 above, where you see the plate with the row of holes; we would have flames dancing through those holes and down from the top of the firebox when previously burning without the catalyst, or heat shield - we unknowingly didn’t help the cracks burning like that ourselves. In the newer Buck 91 manual it shows a diagram which suggests the cat exhausts through that channel to the flue.

bholler; I appreciate the input! When I next remove the cat for inspection, could I install 2 housing gaskets to compensate for the warpage if they will compress enough over the carriage bolts to tighten the housing in place? Like you said, we’re going to run it, and keep watch, until safety and/or efficiency is compromised beyond our tolerance level - safety comes first!

An extra gasket certainly wouldn't hurt

 

[tebenhoh]

UPDATED here:

Buck 91 cracks in metal - UPDATE

Greetings all! Here is our stove update as promised; I’ve started a new thread in order to keep the photos separated, but admins feel free to combine this with the original thread if that is preferable. I’ve pulled the cat and housing, and to me it looks like the two rear corners are the worst...

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