Buck Stove Model 91 Troubleshooting

[Jenlwhi2]

Hello,

My husband and I recently purchased this model wood fireplace insert. We have used it for about 1 week as our only heat source and it's working fantastic heating our 2200sf home! We are very pleased with the heat output.
The issue is, the first day we used it the glass door immediately blackened up. We realized this was due to our improper use of the bypass damper which we have since learned should be open during the heat up phase and closed when the catalyst is active. There was a LOT of smoke that day trying to figure things out.

Yesterday, while the stove was cool I scraped all the black off the glass with a razor blade and had it cleaned up. It burned fairly well and clear for a few hours but by the end of the day the glass was black again. Any time we shut the air intake down to control the heat there would be a lot of smoke in the chamber. The entire inside of the Insert is also coated in black creosote.

I re-scraped the black off again this morning and same story by the end of today.

We have aimed to keep the heat of the combuster right around 1200 all day so we don't feel that it has insufficient heat. Why is it doing this and not burning off the black build up?

A few ideas of things we were doing wrong were that could be a problem are a) we did load logs side to side vs front to back. We have changed that this afternoon.
B) we have been adding a log here and there and opening the door more often..is this an issue and causing excess smoke? How much should we load at a time? C) we were closing the bypass damper immediately after refueling (it says to do this in the manual) but I've read elsewhere that you should leave it open for awhile after reloading. So we aren't sure which is the better way...

Also, our wood is over 1 year old hard wood (mainly red oak).


Any ideas of what we are doing wrong? I realize some is just trial and error to figure things out but this isn't an issue I see most people having so we aren't sure what we are doing wrong!

Would anyone share in detail what your method is?

Picture 1 is yesterday afternoons fire after I cleaned the glass and picture 2 is tonight. The cat temp currently reads 1500°.

Thanks!

 

[Jenlwhi2]

Here's a picture update this morning. I rescraped part of the glass. The black you see if where I didn't scrape.

Before we went to bed the cat probe read 1500. I shut off the left intake and cracked the right intake. Waking up the probe read 600...still lots of coals. The blower had shut off so our house was down to 64°. (In the warmest places).

I just refueled it and leaving the intakes open til it heats up good.

 

[tebenhoh]

Our Buck 91 came with our house; we were not stove owners, nor wood burners, previously, and I am hardly an expert now! This will be our fifth season using it; we only burn when we’re home, weekends and holidays.

First question; are you burning DRY WOOD? Do you have a Moisture Meter? 20% or less seems to be the standard for a catalyst stove.

(Our experience with dirty glass:
We ran our stove overnight one time with both air sliders (left and right) fully closed, and awoke to the black glass shown in your photo. We now leave only the right air open just slightly, and we only get the bottom corners dirty - see my photo. After scraping and cleaning the entire door glass that day, I don’t want to do it again. We did, however, get our best (longest and warmest) overnight burn with the air fully closed! The residue in the corners comes clean with a damp paper towel dipped in the ashes. Scrub with ashes, wipe excess, and then scrub with crumpled newspaper. The side glass always gets dirty, we don’t mess with trying to keep them clean anymore.)

I’ve never seen 1500 deg on our cat probe, maybe 1300-1400 once or twice. Without checking the manual, I believe 1500 is about maxed out. Normal for us is around 1200 as you mentioned.

 

[Jenlwhi2]

Our Buck 91 came with our house; we were not stove owners, nor wood burners, previously, and I am hardly an expert now! This will be our fifth season using it; we only burn when we’re home, weekends and holidays.

First question; are you burning DRY WOOD? Do you have a Moisture Meter? 20% or less seems to be the standard for a catalyst stove.

(Our experience with dirty glass:
We ran our stove overnight one time with both air sliders (left and right) fully closed, and awoke to the black glass shown in your photo. We now leave only the right air open just slightly, and we only get the bottom corners dirty - see my photo. After scraping and cleaning the entire door glass that day, I don’t want to do it again. We did, however, get our best (longest and warmest) overnight burn with the air fully closed! The residue in the corners comes clean with a damp paper towel dipped in the ashes. Scrub with ashes, wipe excess, and then scrub with crumpled newspaper. The side glass always gets dirty, we don’t mess with trying to keep them clean anymore.)

I’ve never seen 1500 deg on our cat probe, maybe 1300-1400 once or twice. Without checking the manual, I believe 1500 is about maxed out. Normal for us is around 1200 as you mentioned.

View attachment 303329

Thanks for the reply!
Our has only stayed as clean as in your picture is when our air intakes are both wide open. As soon as we start to shut them the smoke starts and we end up with black glass.
This morning the picture above was how it looked when we left for church. I closed the intakes all the way on the left and kept the right cracked open. When we arrived home from church the whole glass is black all over again.


Can you walk me through your loading process and how open do you tend to leave your air intake? How often do you have to refuel it?

We do not have a moisture meter so maybe that should be our next step. Our wood is roughly 1 1/2 years old and is mostly split red oak logs so I wouldn't think it would be too wet but maybe I'm wrong!

 

[tebenhoh]

This is how we use our Buck 91; please understand your mileage may vary! It was a lot of trial and error to get comfortable with its operation. Our homes are similar size, though we have a second floor and an open stairway - without running the upstairs furnace, it stays right about 68 up there with the stove going. The first floor where the stove is stays 70-73 depending on the outside temps. We’ve had it 80+ before, but can usually regulate the temp pretty well with the fan/blower.

Here we go…
COLD START
1. Load stove. I start the season with ends and chunks left over, which is what we’re burning now. They get loaded however they best fit to fill the firebox. When we get to the splits, we load N/S (front to back).

Friday after work when I first load for the weekend, I may not pack it full so I have time and space to reload before bedtime. Otherwise we pack it full anytime we’re opening the door.

2. Light the fire.
Damper open. Right and Left air fully open.
I twist a few pieces of newspaper and stuff it in the gaps, then light. I keep the door cracked open while I’m watching it until the wood catches, then close and latch the door.

3. Monitor temperature.
When the cat probe hits 100, I fully close the Left (shotgun) air. Right is fully open. Damper is open.

4. Adjust air.

I’ll continue this after I answer what you just posted… be right back.

 

[tebenhoh]

Thanks for the reply!
Our has only stayed as clean as in your picture is when our air intakes are both wide open. As soon as we start to shut them the smoke starts and we end up with black glass.
This morning the picture above was how it looked when we left for church. I closed the intakes all the way on the left and kept the right cracked open. When we arrived home from church the whole glass is black all over again.


Can you walk me through your loading process and how open do you tend to leave your air intake? How often do you have to refuel it?

We do not have a moisture meter so maybe that should be our next step. Our wood is roughly 1 1/2 years old and is mostly split red oak logs so I wouldn't think it would be too wet but maybe I'm wrong!

I would check your wood, I’ll add a photo of the meter we use which was suggested by someone here. The smoking issue is what leads me to ask about the wood; we really only see smoke at initial startup or reload, and as soon as we have flames the smoke is gone.

Our glass will get dirtier the less air we allow, maybe we’ve found our sweet spot? If you look upside down underneath the little shelf below the door, on each side where the air sliders are, you can see the plates which cover the air intake - you may need a flashlight. During our trial and error I would mark on the slider where we got the best results. I’d say 1/8” open looking at the plates is as far as we close it. We draft very, very well though a 30’+ chimney, so this may not be your sweet spot. I’ll take a photo of this, too. Stay tuned, hope we can help!

 

[tebenhoh]

 

[tebenhoh]

This is the right side slider - we only use the left for cold starts. The gold line to the left in the photo is halfway of the sliders full travel.

 

[tebenhoh]

4. Adjust air continued…
From here on, we only adjust the Right air slider. How quickly the cat probe temp is rising determines when we begin turning the air down - closing the slider. Usually every 200 deg or so I’ll gradually adjust it down. And once it’s hovering around 400 I’ll close the slider to either the middle, or right hand in my photo, mark and leave it until we get 500. (If it will help, I can retake the photo with a tape measure in view, but I don’t want you to think you have to run your stove exactly as we do ours.)

5. Close damper.
We close the damper, engage the catalyst, at 500on the cat probe - recommended by FireCat Combustors (Applied Ceramics), which is what we have in our stove, and the brand noted in the Buck manual. If we haven’t already closed the air to the last mark, we’ll close it that far once the cat climbs to 600.

6. Adjust blower fan, enjoy the heat.
We wait to turn the fan on until 600 on the cat probe since it does pull heat from stove. The temp will drop from 600 when the fan starts, but then slowly begin to rise. Again, that’s our sweet spot. From here I adjust the fan in stages as the cat temp rises if we want the extra heat or faster warm up. Normally we run the fan on it’s lowest setting because it provides enough heat and keeps the stove hotter longer.

The blower (fan) is OFF for our starting, and reloading, procedures.

Disclaimer and additional info…
We burn whatever wood we can get except pine and cedar, but we make sure it’s DRY. I have no idea what’s in the stove now, or for most loads. We’ve found if it’s dry, the Buck will burn it. Given that, I understand different species burn differently, and we don’t necessarily know what we’ll get each time we load. Hopefully this is an easier process for you if you’re consistently burning the same type wood.

I’d say on average we get a decent 6-8 hours of good heat on each full load. And we try not to reload until the cat is below 500. If it’s a sunny day, we have south facing windows, we’ll let it burn down to 200-300 on the probe. Really it depends on the heat we want, and I try to make reloads fit with our schedule, especially bedtime.

For reference, we’ve had our stove running since Friday evening, and the glass still looks like my photo. Often it’s hardly noticeable until the second or third load. We’re right at 500 on the probe now, after a mid morning reload at 9-10am if I remember correctly, and my grill thermometer shows 80 deg air still blowing from the stove. I may add a partial load , and then a full load before bed. We try to keep the door closed as long as possible once a burn has started.

I’ll add how we Reload here in a bit. Cheers!

 

[Jenlwhi2]

This is the right side slider - we only use the left for cold starts. The gold line to the left in the photo is halfway of the sliders full travel.View attachment 303352

Thanks so much for all of your information and for taking the time to type it all out!


We hauled up some wood that is several years old tonight to give it a fresh try tomorrow to see if that helps the black. I guess I'll (once again) scrape all the black off tmrw morning 😆

It has been running right at 1300-1400 for the past 4 hours keeping the left air closed and right air med/low. (My newer one has high, med/high, med/low, low and closed marks on the sliders.) The fan is on low and Our thermostat reads 73 .

Hopefully tmrws wood burns clean without the smoke and the glass with stay clear!
I'll try to update with how it goes.

 

[tebenhoh]

How cool that they labeled the sliders now!
Besides the hassle of the black glass, it sounds like you’ve got it figured out; that’s a great burn you have going. I’d have to say keep doing what you’re doing, and hopefully the wood was damp unless there’s some break-in to the stove I’m unaware of - ours was well used by the time we got to use it.

Other thoughts… have you contacted Buck, or your dealer about the glass issue?
If it’s true, it’s been our experience, that less air = more soot on the door glass, maybe you can mess around with a little more air and still get the burn you want? That would also depend on how well your stove drafts - pulls air through and out the chimney. There does seem to be a sweet spot, it took us a long while to find it. 🙄

Wish you the best, and I hope it’s just the wood. (I’ll still add our reload info if it would be helpful.)

Here’s the link to the “Buck” Wood stoves by Manufacturer forum on here in case there’s something that would help…

Buck Stove

This forum is for discussions and information regarding Buck Stoves

www.hearth.com

 

[Jenlwhi2]

How cool that they labeled the sliders now!
Besides the hassle of the black glass, it sounds like you’ve got it figured out; that’s a great burn you have going. I’d have to say keep doing what you’re doing, and hopefully the wood was damp unless there’s some break-in to the stove I’m unaware of - ours was well used by the time we got to use it.

Other thoughts… have you contacted Buck, or your dealer about the glass issue?
If it’s true, it’s been our experience, that less air = more soot on the door glass, maybe you can mess around with a little more air and still get the burn you want? That would also depend on how well your stove drafts - pulls air through and out the chimney. There does seem to be a sweet spot, it took us a long while to find it. 🙄

Wish you the best, and I hope it’s just the wood. (I’ll still add our reload info if it would be helpful.)

Here’s the link to the “Buck” Wood stoves by Manufacturer forum on here in case there’s something that would help…

Buck Stove

This forum is for discussions and information regarding Buck Stoves

www.hearth.com

Yes I would appreciate you adding the reload Info!


This morning the temp in the stove was around 900-1000 still and lots of coals. I scraped the glass off again and reloaded. I opened both air sliders for a bit and shut down the left side when it got to about 1100. Then I shut down the right one to med low once it got to 1200. Right now we are sitting right at 1500 but there is zero flames unless i open the shot gun air (and sometimes i need to open bypass damper to get flames). I also think there is already a tad of darkening in the corners happening and I can see a small amount of smoke.

Even though I don't have a moisture meter this wood has been out there for a few years so should be extremely dry.

I'm not sure what else to do since the heat is already running pretty high. If I open dampers to get some flame it's gonna get too hot in there.


Does your flame most of the time or most of the time no? I'm okay without constant flame as long as it's not just smoldering and causing blackening.

I have not called the dealership or manufacturer yet. My plan was to try out this dryer wood and see how that goes and call if we are still not figuring it out.


Attached is picture of stove this morning when I firsr reloaded(some flames) and then again a few minutes ago with the temp around 1400-1500°(no flames)

 

[moresnow]

Soooo. Just to clarify for anyone following. Your listed temps represent Catalyst temp. Not stove temp. Your zero flame burns are very normal in many Cat equipped stoves. This is how they get such exceptional long burns.
Dirty glass can be caused by a few different issues. Turning down air to soon. Turning down air too far. Wet fuel. Wet fuel being most suspect.
Not sure if you have a moisture meter? Get one. Bring a nice selection of your splits indoors to get them up to room temp. The next day take them back out and re-split them. Immediately test the freshly exposed inner face with the meter pins inline with the grain. This will give you an accurate moisture content.
Sounds like you are getting things worked out. Good luck.

 

[Jenlwhi2]

Okay I called the distributor where we bought our insert and they are saying that our chimney flue isnt drawing well and that we need to install a pipe to heat and draw better. Does this sound right to anyone?

My dad suggested simply not using the catalyst and leaving the bypass open because once we do that we get flames and no more smoke..

Thoughts? We really hate spending the $750 on flue pipe if it doesn't end up fixing our issue.

 

[tebenhoh]

I believe you’ll need some of the professionals here to chime in on this; I’m not qualified to comment on installations other than the basics, and what the Buck manual says is required.

Is there any type of flue pipe attached to the top of your stove?

 

[Jenlwhi2]

I believe you’ll need some of the professionals here to chime in on this; I’m not qualified to comment on installations other than the basics, and what the Buck manual says is required.

Is there any type of flue pipe attached to the top of your stove?

No, we simply Installed the insert directly into our existing fireplace with a regular brick chimney. When we purchased it they said we might need to pipe and that it was recommended to draw better but my dad didn't think it would be necessary.


What's confusing to me is this: why are we getting good draw and no issues when we leave the bypass open? Would a pipe really solve our issues? Maybe I should start a new thread with my direct question about this.

 

[tebenhoh]

Look at pages 8-9 in the manual; if you don’t have one, here’s the link. Scroll to the bottom and there’s a pdf of the manual.
(We have a fully insulated liner from the stove up the full length of our chimney.)

Buck Stove, New Buck Corp

buckstove.com

When you close the damper, it redirects the way air flows through the stove so it all goes out (exhausts) through the catalyst. With the damper open, everything goes straight out the top of the stove - no restrictions.

You may get more/better responses with a new thread, you can certainly try it. I’ll still add the rest of our operating info here.

Please get a carbon monoxide detector if you don’t have one, and plan to continue using the stove… there is nothing to prevent fumes from entering your living space with your current installation.

 

[tebenhoh]

5. Close damper.
We close the damper, engage the catalyst, at 600. If we haven’t already closed the air to the last mark, we’ll close it that far once the cat climbs above 600.

I’ve edited this to remove the 500 deg catalyst engagement, it should read 600 deg on the cat probe to close the bypass. I misread the FireCat Combustors recommendation of 500 deg “firebox” temperature in their FAQ’s section. Please pardon my misinformation. 🤦‍♂️

 

[tebenhoh]

Buck 91 Re-Load:
Again, you’re mileage may vary! For reference, we have 300 on the probe, and I’m getting ready to reload. It’s 74 in the house right now after burning overnight, and reloading at 7am with 3 big chunks - I didn’t pack it full since it’s 45-50 outside and raining here. It’s just after 12pm now. If it was a bedtime reload it would be the same, but I’d pack the stove full. I’m going to pack it the full width, but there will be space in front and behind the chunks.

1. Load wood.
Turn off fan blower, open bypass, give it a minute before opening the door.
We spread out the coals since it makes reloading easier, especially trying to reach to the back when burning the chunks and ends- yes, we use long fireproof gloves!
Load the wood as quickly and evenly as is safe, and close the door.

You’ll get some turbulence and ashes flying when you first open the door, but ours calms down once the door is fully opened. Be careful!

2. Monitor temp, Adjust air.
From here it’s basically the same as a cold start except we don’t need the left air slider if there’s coals. Open right air slider all the way, and then close it back in stages as the cat probe temperature rises. You may choose to use the Left air slider also, whatever your preference.

3. Engage catalyst, Close damper/bypass.
At 600 on the cat probe, close the damper. Again, we’re usually at our cruising air setting when we hit 600, so we close the damper, let the temp rise a bit, and turn the fan back on. That’s it… enjoy!

That is our normal, preferred, reload. IF it’s necessary to reload with the cat above 600, I do it as quickly as safely possible - I know what piece(s) of wood I want where before I open the door, and they’re close at hand. AND, you absolutely have to use DRY wood for this!

Fast Fire Re-Load:
Put on gloves. Turn off blower. Open bypass. Air slider stays as it is.
One hand on door handle, other hand is holding the piece of firewood.
Open door, place wood, close door. Repeat as needed.
Close damper, watch cat temp.
If for some reason the cat temp falls below 600, I’ll open the bypass, which also pulls more draft, and get the temp back up. Usually I can leave the air slider where it’s set. And usually we don’t drop below 600, often the temp will rise slightly from opening the door.

Hope that helps you guys along… Cheers and Happy Thanksgiving!