New Woodstock Keystone install

[DBoon]

My new Woodstock Keystone is finally here, installed and running very well. Thanks to all those who gave me feedback on this stove and my installation over the past few years.

It runs very predictably and in a very well-controlled way. My installation is rear-vented into double-wall stove pipe with about a 2 foot horizontal run, then two forty five degree elbows to get to vertical, then a pipe damper, and a short vertical section connecting to double-wall chimney pipe (25' straight up). Of course, there is an insulated block-off plate. Combustion air is supplied from the outside. This installation is first-class compared to the previous home's installation.

I ran they Keystone a little conservatively for the first few fires until I understood how much the draft would impact the stove top temperature. Now, the procedure is pretty simple - 1) reload stove on coals, 2) let good flames get going in the firebox and shut the bypass, 3) at 250 degrees F stovetop, shut the air down to 1, 4) close the pipe damper at 400 degrees F. Cat lights off predictably when I shut the air down to one, stove top temp climbs very gradually from 400 degrees (after I close the pipe damper) to 550 or 600 degrees (depending on load) over a period of two or so hours and remains there for two or so hours before starting to fall back. With a full load of wood, I'll get some nice secondary combustion for a couple of hours once the stove top hits 500 degrees or so, and that is a nice bonus to see that secondary combustion (I enjoyed that on my previous tube stove). I have good quantities of coals to relight after 12 hours of burning (and a 250 degree stove top temperature) as long it's not a partial load or an all cherry load. In short, this stove is everything that everyone described to me, and I am very pleased with it. It doesn't overheat my 1750 square foot well-insulated cold-climate house during a 12 hour burn.

I do have a couple of questions for those with this stove:

1. During the first couple of burns, I had some backpuffing (explosive light off of combustion gases) that would result in smoke leakage at the seams. I don't have this now. Is this normal for this stove until the seams seal during the first couple of fires? I think I have the startup and burning process figured out so I also really don't get the backpuffing now, but once in a while I do but I don't have smoke leakage anymore.
2. I still (after about 10 or so burns) have that hot cast iron smell after the stove top heats up to 500 degrees or more. Its less noticeable now than it was initially, but I can still smell it if I come in from the outside. My house is very tightly constructed (with an HRV). Is this normal with a cast iron stoveand/or will this go away after a while? I know it is the cast iron (not the paint) because it smells just like if I heat an empty cast iron pan on my kitchen range.
3. Is 600 degree stove top what you see on this stove at the peak of the burn cycle?
4. I've got a thicker coating of residue on the bottom half of the glass (conveniently behind the andirons, argh) - the top half seems to self clean pretty well with the secondary combustion. This happened during the first two or three burns as I was figuring out the stove. Once I clean that off, will that stay clean or will that residue reappear? Or should I just wait for a bunch of fires to take care of itself?

FYI, the ordering, delivery and customer service process was very smooth - placed my order in April or so and was told probably September delivery, then it became early November, then late November - all ok, I get that they are busy and also likely dealing with supply chain issues. Everyone at Woodstock was super helpful and easy to work with. Stove arrived uneventfully and undamaged.

Lastly, I can't imagine fussing with a tube stove again after having this stove. The two different tube stoves I had were well-constructed, good stoves. But the amount of control and lack of babysitting needed to get a good, clean sustained burn on the Keystone is way less than on the two Lopi stoves I ran (and I think this is true for any tube stove, not just a Lopi). And the Keystone does a great job of moderating the strong chimney draft as well.

 

[3650]

Very nice. I had a fireview. Woodstock makes top notch stoves.

 

[Todd]

Nice looking install! I burned a Keystone for many years, it’s a great little stove. I had an occasional back puff during certain weather conditions or when I turned it down too low too fast. The smell is probably just breaking in a new stove. As it gets hotter and hotter you may have some smell til she’s broke in well. I think the glass will clear up with hotter fires. Lower burns below 1 will do that. I mostly ran mine around #1, a bit above when I needed more heat or a bit below for less heat and long burns.

 

[moresnow]

Nice to hear a positive new stove story! Sounds as if you have covered the basic operation safely. Now the fine tune will come in time. Congrats.

And coming from a twice over tube stove owner/operator to boot
Nice contribution. Enjoy

 

[begreen]

The stove looks great in that setting. I've always liked the Palladian and Keystone. It's good to hear that it's working out well for you.

 

[brenndatomu]

Very nice!
Before I actually clicked on the second pic and blew it up I thought the two windows were his n hers tvs!

 

[begreen]

Very nice!
Before I actually clicked on the second pic and blew it up I thought the two windows were his n hers tvs!

They're Marvin's tvs.

 

[Woody Stover]

procedure is pretty simple - 1) reload stove on coals, 2) let good flames get going in the firebox and shut the bypass, 3) at 250 degrees F stovetop, shut the air down to 1, 4) close the pipe damper at 400 degrees F. Cat lights off predictably when I shut the air down to one, stove top temp climbs very gradually from 400 degrees (after I close the pipe damper) to 550 or 600 degrees (depending on load) over a period of two or so hours and remains there for two or so hours before starting to fall back. With a full load of wood, I'll get some nice secondary combustion for a couple of hours once the stove top hits 500 degrees or so, and that is a nice bonus to see that secondary combustion (I enjoyed that on my previous tube stove). I have good quantities of coals to relight after 12 hours of burning (and a 250 degree stove top temperature) as long it's not a partial load or an all cherry load. I do have a couple of questions for those with this stove:

1. During the first couple of burns, I had some backpuffing (explosive light off of combustion gases) that would result in smoke leakage at the seams. I don't have this now. Is this normal for this stove until the seams seal during the first couple of fires? I think I have the startup and burning process figured out so I also really don't get the backpuffing now, but once in a while I do but I don't have smoke leakage anymore.
2. Is 600 degree stove top what you see on this stove at the peak of the burn cycle?
3. I've got a thicker coating of residue on the bottom half of the glass (conveniently behind the andirons, argh) - the top half seems to self clean pretty well with the secondary combustion. This happened during the first two or three burns as I was figuring out the stove. Once I clean that off, will that stay clean or will that residue reappear? Or should I just wait for a bunch of fires to take care of itself?

Lastly, I can't imagine fussing with a tube stove again after having this stove. The two different tube stoves I had were well-constructed, good stoves. But the amount of control and lack of babysitting needed to get a good, clean sustained burn on the Keystone is way less than on the two Lopi stoves I ran (and I think this is true for any tube stove, not just a Lopi).

View attachment 306372 View attachment 306373

Wow, that looks great, DBoon! 😎
I start with the air open to 2 or 3, cutting it as more wood gets burning. I can close the bypass once the stovetop is over 150, then keep some flame going to get the cat glowing, then cut air in increments to cruise setting. I end up with the air somewhere between .5 and 1, depending on what I'm trying to do. If I need more heat I'll keep some flame in the box, which heats up the sides more. Stovetop above the cat usually peaks about 500-550, occasionally 600. When the splits get to the coaling stage, I may open the air a bit if I need heat while the coals burn down. I can keep the stovetop 300-350 doing that, and sometimes get small, blue flames depending how many volatiles are left in the splits.
Yeah. when you get the secondary burn from the airwash, as in your two pics, you'll get some gunk on the lower half of the glass.
The backpuffing may have been due to some moisture coming off the new stone, I don't know. Once it a while I'll get a flash-over in the box but I hesitate to call it a "backpuff" since it's not that forceful.
The burn I'm going for now is intermittent low flame distributed around the box and coming off the wood. I moved the magnet I had on the ash pan housing hole, to feed more air to the bottom of the load and try to get ignition further back in the box. You can somewhat control where the air comes in by stirring the ash down with a poker through certain areas of the grate.
I've toyed with the idea of a tube stove...the Lopi Endeavor has an ash grate, a feature I like on the Keystone. I also like the PE stoves for their simplicity of construction and maintenance. But those two brands don't offer rear venting, and I like that clean look. So that leaves Jotul or maybe a Woodstock Absolute. I'd need to raise the lintel one brick higher to fit the AS. And I'd have to learn more about how the secondary works on that stove.
But now you're talking me out of the tube stove idea 😆 and I really like the control over the burn that I have with the Keystone, and I find that playing with all the options is half the fun of burning wood. As it stands now, the Keystone can handle all but the coldest weather here: Then I might need a boost every few hours from the oven or a little quartz heater we have. With more weatherization of this old cabin, the Keystone will do even better.
Great review, and I hope you'll keep us updated as you fine-tune your operation of the stove. 😀

 

[Woody Stover]

I've got a thicker coating of residue on the bottom half of the glass (conveniently behind the andirons, argh) - the top half seems to self clean pretty well with the secondary combustion. This happened during the first two or three burns as I was figuring out the stove. Once I clean that off, will that stay clean or will that residue reappear? Or should I just wait for a bunch of fires to take care of itself?

My glass doesn't stay as clean as you'd see on a tube stove, but it's pretty easy to clean it using a distilled vinegar/distilled water mix and a paper towel. Or if it's stuck on a bit in a lower corner I'll use a scouring pad that's rated safe for ceramic cooktops.
Yeah, with the andirons you need to flatten your hand out to get past 'em. 😏
When I first came here asking about what stoves I should consider to get a bit more heat than the Dutchwest 2460 was giving me, the Keystone was one of the stoves begreen mentioned. I knew of Woodstock because a SIL had picked up a used Fireview a couple years previous. I liked the quality of her stove, and the ash grate and big window of the Keystone, I took the plunge, and am happy to this day. 🤗

 

[SpaceBus]

They're Marvin's tvs.

That's my favorite kind! Good looking stove install as well.

 

[Woody Stover]

That's my favorite kind!

Catch me up...what's a "Marvin's tv?"

 

[SpaceBus]

Catch me up...what's a "Marvin's tv?"

They are Marvin windows, they are usually very expensive, but well made windows.

 

[Woody Stover]

Well, DBoon, you got me to clean my glass. 😏 Fire was pretty much out, so I did it. BTW. what color is your stove, the metallic blue? Mine is, and it's more gray than blue...I like it.
It wasn't cold in the house but I had to fire up a short load to look at the clean glass. 😄
I did a top-down start and left a little space between the front log and the second, and was able to get a burn with flame in the front, and in the middle. When I cut the air and the fire got lazy, I got some cool intermittent, gentle flashovers across the bottom of the cat scoop.
The cat wasn't glowing very bright since the flames were burning some of the smoke. I didn't help seeing the cat in the pic, when I forgot to brush off the cat scoop screen after I got done with the glass. DOH!!


https://youtu.be/n7lgQlCqkdU

 

[Woody Stover]

Floater ribbon burn. 🤗

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Wraith burn.

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[DBoon]

Hi Woody Stover,

I just now saw your replies - I hadn't realized the thread was moved. Thanks for the feedback! I got a lot of good advice from you when I was looking at this stove. I get those same types of flames with my Keystone - they either sit right below the cat in the pan, or (if I have more wood in the firebox) throughout the firebox. I've had the one dancing up the middle of the glass in the front of the stove as well. If I get the perfect burn, I don't see too many of the flames. I have the metallic blue cast iron finish - this goes great with the soapstone and also with the bluestone hearth and lintel. I love using the stove - so much more predictable and less finicky than a tube stove, and the cat does a nice job of slowing the draft down in the tall chimney pipe. I would never consider going back to a tube stove.

New Questions:

1. I am pretty anal about burning cleanly, and this stove burns clean. I have found that if the stove top goes much above 600 degrees F with a stuffed full load of wood (including some smaller pieces to fill up the nooks and crannies) that I get smoke out the chimney. I think that this is because the pipe is drafting too much and pulling smoke through the cat too fast and the cat can't burn all the smoke particles. The cat is still orange and doing it's thing, but not as well as it should. Is this, in fact, what is likely happening? The two times that I saw this happening I think I might have had a wetter piece of wood in the firebox as well. I suspect that was a contributor since there were black spots on the cat in a sea of orange glow (due to moisture from a wetter piece of wood?). Any feedback is appreciated.
2. I have rear-vented my stove - can anyone tell me if it is possible to install the cat thermometer when the stove is rear-vented? I haven't found that I have needed the cat thermometer it to get a good startup/burn, but I would like to solve the mystery as to whether this can be installed with a rear-vented Keystone.
3. I have a 27' tall, 6" chimney pipe. I followed Woodstock clearance installation instructions (10" from front of hearth) but the wood floors 10-16" in front of the stove got very hot during the peak of the burn. I have since laid a piece of aluminum foil over the wood floors in front of the glass, and that solves the problem (floor cool to touch underneath that foil). Does anyone else have this experience? My previous tube stove would do this as well with really hot burns, despite meeting clearances.

Updates on my first post:

1. Startup process from coals is still pretty much unchanged from my first post. I'd say that I've tuned up the shutdown process a little more - get flames, close bypass at a 250 stove top (which is about normal when I reload), pretty quickly close air from 4 to 1 (remember, I have a 27 foot chimney), close pipe damper at 400 and also turn air to 0.5 at that point. A couple of times with a full load I've gone to 0.25 on the air supply.
2. The glass is just dirtier than my tube stove. I think this has more to do with my using a pipe damper to slow the pipe exhaust down. My wood may also be a little on the moister side than ideal.
3. To clean the glass (after cool down), I just remove the andirons with a 1/2" box wrench and scrape the harder stuff in the corners with a razor blade and use vinegar in the middle of the glass. I'll try Woody Stover's stovetop scrubber brush trick soon. I'm not sure why I bother - the glass just gets dark again after one fire.
4. I had a big backpuff last night, but no smoke leakage through the seams. I think the seam seals just needed time to heat up and expand and now that they have, the backpuff doesn't force exhaust through the seams. Glad that resolved itself.
5. I don't smell the cast iron odor anymore, thankfully. That took about two weeks to go away. It wasn't bad, but I wouldn't have wanted to live with it forever.

Just today, using the normal startup process, I was at 250 degrees bypassed and air setting to 1. An hour later the stove was at 500 degrees (pipe damper closed and air setting to 0.5 as stovetop reached 450 degrees). The stove peaked at 600 degrees and cruised above 500 degrees for two hours and fifty minutes, two hours or more of that time at 600 degrees. This was with mixed hardwoods - a piece of hickory, a piece of ash, a piece of hard maple and a piece of cherry. Stove was not stuffed - there were some oddball sized pieces and lots of empty space in the firebox. I'd be lucky to get 2 hours with that same load of wood above 500 degrees F (probably peaking at 600 F for 30 minutes or so) with an old, similar firebox sized Lopi Answer. That's why I think this stove is 25% or so more efficient than my old tube stove.

I've experimented with the magnet over the hole in the ash pan. I think I've decided that it's good to know where that air inlet is and how to cover it, but the pipe damper closed and the air set to 0.5 does what I need, and the glass is just going to darken up with the pipe damper closed - maybe with drier wood next year it will be a different story.

Just an FYI, my house is two stories and 1750 square feet - 1000 on the lower floor, 750 upstairs. The heat loss is 18,000 BTUs/hour at 0 degree F outdoor temperature. Upstairs heat loss is only 1/3 of that (better/newer windows upstairs, well-insulated attic and attic hatch). My routine is to run the stove on a 12 hour reload cycle and let the radiant floor heat pick up the slack. The radiant floors are powered by a geothermal heat pump - when I'm running the woodstove I just adjust the outdoor reset controls on the geothermal system so that the water temperature is about 15 degrees less than it would otherwise be. Then, the water circulates in the floors all the time (i.e., floors warm) and the stove does the balance to keep things warm upstairs. Downstairs is a mostly open floor plan so that is a comfortable 70 degrees on days that I run the stove (just right). This stove is basically perfectly sized. If I had to run it in a power outage (I experimented already), the upstairs would be between 60 and 62 degrees (depending on outdoor temperature) and the downstairs 70 degrees. I could run it hotter/harder to get more heat (e.g., load three times per day).

 

[Woody Stover]

New Questions:
if the stove top goes much above 600 degrees F with a stuffed full load of wood (including some smaller pieces to fill up the nooks and crannies) that I get smoke out the chimney. I think that this is because the pipe is drafting too much and pulling smoke through the cat too fast and the cat can't burn all the smoke particles. The cat is still orange and doing it's thing, but not as well as it should.

1. I have rear-vented my stove - can anyone tell me if it is possible to install the cat thermometer when the stove is rear-vented? I haven't found that I have needed the cat thermometer it to get a good startup/burn, but I would like to solve the mystery as to whether this can be installed with a rear-vented Keystone.
2. I followed Woodstock clearance installation instructions (10" from front of hearth) but the wood floors 10-16" in front of the stove got very hot during the peak of the burn.

Updates on my first post:

1. Startup process from coals is still pretty much unchanged from my first post....get flames, close bypass at a 250 stove top (which is about normal when I reload), pretty quickly close air from 4 to 1 (remember, I have a 27 foot chimney), close pipe damper at 400 and also turn air to 0.5 at that point. A couple of times with a full load I've gone to 0.25 on the air supply.
2. The glass is just dirtier than my tube stove. I think this has more to do with my using a pipe damper to slow the pipe exhaust down. My wood may also be a little on the moister side than ideal.
3. To clean the glass (after cool down), I just remove the andirons with a 1/2" box wrench and scrape the harder stuff in the corners with a razor blade and use vinegar in the middle of the glass. I'll try Woody Stover's stovetop scrubber brush trick soon. I'm not sure why I bother - the glass just gets dark again after one fire.

Just today, using the normal startup process, I was at 250 degrees bypassed and air setting to 1. An hour later the stove was at 500 degrees (pipe damper closed and air setting to 0.5 as stovetop reached 450 degrees). The stove peaked at 600 degrees and cruised above 500 degrees for two hours and fifty minutes, two hours or more of that time at 600 degrees. This was with mixed hardwoods - a piece of hickory, a piece of ash, a piece of hard maple and a piece of cherry. Stove was not stuffed - there were some oddball sized pieces and lots of empty space in the firebox. I'd be lucky to get 2 hours with that same load of wood above 500 degrees F (probably peaking at 600 F for 30 minutes or so) with an old, similar firebox sized Lopi Answer. That's why I think this stove is 25% or so more efficient than my old tube stove.

I've experimented with the magnet over the hole in the ash pan. I think I've decided that it's good to know where that air inlet is and how to cover it, but the pipe damper closed and the air set to 0.5 does what I need, and the glass is just going to darken up with the pipe damper closed - maybe with drier wood next year it will be a different story.

I could run it hotter/harder to get more heat (e.g., load three times per day).

Great, detailed update, DBoon. Thanks! 👍
Yes, you can sometimes blow smoke through the cat too fast and it won't get burned. I haven't quite figured that aspect out yet. Sometimes I can run flame and be fine, other times smoke gets through. When it's light out and I can see the stack, a lot of times I'm just gliding on coals, and don't fire a load until it cools down later in the day...and it may be dark so I don't get to see if I'm burning clean. Then again if the wind is right and the exhaust gets blown down, I can tell if it's smoky. I don't think my wood floor in front of the stove gets very hot but I'll check next time the cat is blazing. Or did you have flame in the box at the time as well? I, too, think that an occasion split that got rained on can affect how quick you can get the cat glowing, and how clear the glass stays as well. But I'm not going to burn a big flame and send BTUs outside, just to clean off the glass. It clears to some degree when I burn in the next load, and that's good enough for me.Usually the middle third stays pretty clear, side thirds may also be clear, or maybe a bit darker, depending on those factors. I'm not sure how clean these cat stoves actually are in real-world burning, vs. the EPA test burn. When cruising with the wood smoldering, creo builds up in the box. Then when you reload and fire it for a while with the bypass open, you can smell some of that stuff burning off and going straight out the bypass. There's a hole on the back of the stove, above the air control lever. You can see the probe dial on mine, with a paper clip marking 1000* since the back of my stove is flush with the masonry fireplace opening and it would be hard to see without a mirror. But you need a probe about 8" long so the cat temp is diluted, and what shows up on the dial is basically the temp at the flue collar. That is useful, but pretty much runs parallel to the reaction of the surface meter that I have lying on the tee snout, about 6" back of the flue collar. I'll get an Auber probe or something in there at some point, and the transmission line may be insulated and give a true cat temp reading...?

 

[DBoon]

Hi Woody Stove,

Re: the smoke through the cat, yes, it has happened with flames in the firebox and >600 stove top temperatures. I think that more aggressive shutdown earlier is the key, and I'm getting better at that.

Re: the cat probe, I'll try to find that access point during my next shutdown. Realistically though, that location won't be too convenient for me to look at given my slightly recessed installation. No big deal though - the stove operates very consistently and I haven't felt the need for the cat probe, or even a flue temp probe for that matter.

Update - Last night's burn (half round of hickory, two cherry splits, hard maple split):

1. Followed my procedure for startup and shutdown
2. About 55 minutes after reload, stove top was at 450 degrees.
3. One hour and 45 minutes later, stove top reached 500 degrees on the way to 550 degrees
4. Stove cruised at 550 degrees for 2 hours and 50 minutes (last 10 minutes dropping to 500 degrees)
5. Another 10 minutes and the stovetop was dropping below 450 degrees
6. All cat and no flames the entire time - 4 hours and 45 minutes above 450 degrees stovetop. Got to love that.

I have to love dry hickory in this stove. When mixed with cherry or maple, the hickory kicks in late, strong and steady and really extends the burn time. Just starting a morning burn with a similar (slightly larger load) and it seems to be going even better than what I described above.

 

[Todd]

Sometimes I miss my Keystone, it’s a great little stove. You will find that stove top temps don’t tell the whole story though. I’ve seen a black firebox with a 700 STT and you’d think the heat is just pouring off the stove but realistically it’s all on top of the cat. Get some flame in the box with a 500-600 STT and the whole stove is radiating some serious heat.

 

[Woody Stover]

I think that more aggressive shutdown earlier is the key, and I'm getting better at that.
Re: the cat probe, I'll try to find that access point during my next shutdown. Realistically though, that location won't be too convenient for me to look at given my slightly recessed installation. No big deal though - the stove operates very consistently and I haven't felt the need for the cat probe, or even a flue temp probe for that matter.

Right. Loading on a coal bed with the stove top at 250-300, I can fire the stove at a medium rate (don't wanna subject the bypass frame to too much heat,) then in about 15-20 min, after I have a sufficient amount of wood gassing, cut the air to about 1.25-1.5 to keep throwing flame heat to the cat, close the bypass and get a glowing cat in short order. Then I cut the flame back lower and let it go a while, cutting air in steps until I'm sure I can got to cruise air level without crashing the cat.
But like you said, a piece of damp wood can throw you a curve ball, so every load is different...more of an art, since the science is too complex. 🤓 Like it is for the social media armchair pundits to come up with two-sentence solutions to the world's problems. 😆 Ya know, I try not to rave about this stove too much, figuring that folks will assume that I'm just another "homer" pumping his own stove, as some on here will do from time to time with their lesser units. If they made a Keystone with a box the size of the Fireview, I'd be on that like powderpost beetles on Hickory. So how did this morning's burn go? You seemed to have high hopes for it..

 

[DBoon]

Had a nice , thick hickory coal bed to start the morning. Two big splits of hickory, an ash split, and a medium and smaller cherry split. An hour after reload, the stove was stalled out at 280 degrees stovetop temperature, so I opened the air back up a bit and the cat started glowing. 30 minutes later it was at 400 degrees stovetop, and I shut the pipe damper and turned the air down to 0.5. An hour later it reached 500 degrees, then cruised for 4 hours between 500 and 550 degrees (mostly at 550) before falling back down to 400 degrees 15 minutes after dropping below 500.

Not a bad burn! I was tempted to let it sit forever at 280 degrees and see if it the cat would ever kick in but I was worried about plugging the cat, and it was cold outside and I needed heat in the room as well.

It's a little warmer tomorrow in the morning, so I will let it burn out overnight and clean it out. It has earned its rest.

 

[DBoon]

I’ve seen a black firebox with a 700 STT and you’d think the heat is just pouring off the stove but realistically it’s all on top of the cat.

Yeah, that's what I'm aiming for - those long, slow cat-only burns. I'm getting better at regulating the stove early to let it settle in low and slow. With my tall chimney, I think it will be tough to dial it in perfectly, but I am getting pretty close.

 

[Woody Stover]

Coulda been that you didn't have enough wood burning at first, and the cat wasn't getting enough smoke to burn. In that case, the cat could still be burning, just not glowing. Should be at 280 stovetop, unless you just really fired the box initially. Hard to believe you didn't have enough wood burning at that point, though, with big flame. The fact that you opened the air and then the cat took off seems to indicate that the cat may have been wanting more smoke. Or maybe you had a damp split in there..
You'll find that the more dense woods--BL, Hickory, White Oak etc, take a bit longer to burn in initially. You'll get a better feel as you go, for whether you have enough wood burning, by eying the bottoms of the splits that are on the coals, etc.
A trick I use sometimes with dense woods is the old BrotherBart "Tunnel of Love." (Patents and trademarks apply.) 😏 Make a trough running front to back in the coals, which allows more air back there to get multiple splits burning.
But as I've said, if I keep some flame heat going to the cat, I can generally close the bypass at 125-150 and get the cat glowing in short order, provided enough wood is gassing.

Re: the cat probe, I'll try to find that access point during my next shutdown. Realistically though, that location won't be too convenient for me to look at given my slightly recessed installation. No big deal though - the stove operates very consistently and I haven't felt the need for the cat probe, or even a flue temp probe for that matter.

That's why I'm interested in the digital probe instruments and thermocouples from auberins.com. I think those will transmit the true temp, within a half inch of the cat, rather than the analog 8" Condar which ends up being a flue exit temp meter. Don't get me wrong, that temp can be useful as well, similar to but maybe a little better than a stovetop meter lying on the tee snout like I have now. I was using that tee snout meter for a while, running it up to 500 or so, holding there for maybe 10 minutes, then closing the bypass and getting a reliable glowing cat. But it's a pain to see it; You have to bend over with a flashlight, and still you are looking at the dial from an angle so it's hard to read. But as you said, you can run the stove without that stuff.
I've kind of been ignoring the cat probe (flue exit probe) since it was hard to see the face with the fireplace bricks blocking access..needed a mirror. But now that you guys have got me thinking about it again, I may put some temp marks on the back of the dial so I can try the same idea I was doing with the snout meter; Get the cat meter up to X degrees for Y minutes and get a reliable light-off every time, once I know what those numbers are.
I'm thinking that if, say, I have a damp piece of wood in the load, that meter would take longer to get to the temp I need, so I could in effect remove that variable. Once I have the required temp for X minutes, it should be good to go....maybe, we'll see. 😆
I'm also thinking that digital probe meters could refine those procedures even further. Hey, I'm a nerd, playing around with this stuff is half the fun for me. 🤓 🤗
Rigging the flue probe seems like it would be a summer project, but I can get the cat probe in there pretty easily.

 

[Woody Stover]

And with the digital probe readout for cat and flue, I can monitor the burn-in from the comfort of of my desk chair without having to get up, walk over there, and waste precious time that could instead be wasted online. 😆 Besides, I'm an old man and I have a limited number of get-ups left in me. 😉
So when I fired the night load earlier, I looked at both meters. Tee snout was at 300 or so, when flue exit was 500.

 

[DBoon]

Hi Woody Stover,

There was a guy on another forum who instrumented his Absolute Steel and reported on the burns using data acquisition systems. I am trying not to be that guy, ha ha, because if I'm not careful I will become that guy and, while it is very interesting, I want to take steps to make sure I don't become that interested . Therefore, no automated data collection.

Having said all of that, I did do some manual data collection. I have found that closing the pipe damper sooner rather than later is the key to getting longer and slower burns and cleaner burns (i.e., not so hot that smoke blows through the cat at a very high temperature burn). Here are a couple of examples (using manual data collection). We will have some well below zero temps coming up during the coming week, so I am looking forward to getting some big, squared-off hickory splits in the Keystone and seeing how long and well-controlled a burn I'll be able to achieve.

Full load - 1/2 hickory, a cherry split, an ash split on a pretty good coal bed, stove top about 250 degrees F.
I think there was some flame activity in the stove, but not too much. I probably could have shut the fire down sooner.
00:00 Loaded, left door open a little bit for a few minutes, then closed it
00:15 Closed bypass, set air to 1, stove top 300 degrees F, cat is black for a long time
01:05 Closed pipe damper, set air to 0.5, stop top 370 degrees F, cat starts to glow orange right away
01:15 Stove top 400 degrees, cat is back to black
01:35 Stove top still at 400 degrees, cat is starting to glow again
01:50 Stove top at 425 degrees
02:05 Stove top 450
02:20 Stove top 490
02:35 Stove top 520
02:50 Stove top 540
03:05 Stove top 550
03:50 Stove top 560
04:05 Stove top 580
04:20 Stove top 580
04:35 Stove top 550
04:50 Stove top 500 (cat no longer glowing, black)
05:55 Stove top 350
06:40 Stove top 310 (opened air to 1)
07:25 Stove top 320 (closed air back to 0.5)
09:10 Stove top 300

2/3 load - 3/4 hard cherry (crotchety wood) and a piece of hickory
I shut the pipe damper early to slow the exhaust through the cat - that seems to be the trick to get the cat to burn hotter and earlier. Despite this being a more marginal wood and smaller load, I get a nice extended burn (for what the load was).
00:00 Reload, door left ajar to let fire catch
00:05 Closed door, then closed bypass, but opened bypass again shortly after. Stove top 220
00:20 Closed bypass, stove top 200
00:30 Set air to 1 (from 4), stove top 250
00:35 Closed pipe damper, stove top 320
00:40 Set air to 0.5, stove top 340, cat is black, what is coming out of the chimney is clean/steam
00:50 Stove top 350
01:10 Stove top 340. I am going to be patient - cat seems to be working even though temp is dropping on stove top
01:25 Stove top 350. Patience pays off, cat is starting to glow
01:40 Stove top 370
01:55 Stove top 400
02:10 Stove top 430
02:25 Stove top 460
02:40 Stove top 470
02:55 Stove top 490
03:10 Stove top 510
03:25 Stove top 520
03:40 Stove top 530 (left house for an hour)
04:40 Stove top 480 (cat is black) (returned to house but left shortly thereafter)

 

[Woody Stover]

I remembered I had a 2" mirror on a telescoping rod, so until I get a digital cat probe installed I'm using the analog Condar probe to track temps around the flue exit. My probe is 8" but since it's only reporting flue exit temp and not real cat temp, you could just use a shorter analog probe there.
The back of the stove is flush with the fireplace opening, and the mirror makes it easy to read the probe dial, which faces back into the fireplace. I also have the rear heat shield installed to keep heat from radiating into the external fireplace masonry and exiting the house. Keeps the stove hotter, I think. The mirror can easily slip between the probe dial and rear heat shield. You can see the paperclip marker (and its shadow) that I was using, before I thought of using the little mirror. I guess I could get rid of that now.



I did a couple of partial loads, a couple of days ago. Neither was particularly long. Documentation notes aren't that great either, so bear with me. I think I'm getting a little better at it as I go. 😏
Like DBoon's reports mine sometimes have gaps where I made something to eat, left the house or whatever. Or once the load is coaling and there's not much happening, I may have some longer time gaps between readings.


First recorded load I put in a half-round of Hedge, about 5-6" thick, original diameter about 12". I put the round part against the back wall so the spaces in the back corners where the half-round curved were lost space in the little 1.4 cf box (that's what EPA says, but I though I measured it at one time and came up with slightly more volume, I'll have to check again.)
I filled in with a Cherry split on top of the Hedge, a couple little kindling and a slightly punked hard Maple split on the coals in front. These get burning fast, so when I come across them I use them to kick off new loads. Then I put a solid hard Maple split on top of that.

0:00 Stove 150, Probe --- Air 2
:10 Stove 250, Probe 325, Air 1 I guess I closed the bypass here..? 🤔
:15 Stove 300, Probe 450 Flame goes out, but I figure the cat is burning by the quickly rising temps.
:20 Stove 350, Probe 470, Air .8 After this air cut, cat begins to glow.
:30 Stove 440, Probe 480
:50 Stove 450, Probe 480, Air .5 After this cut, cat glows brighter.
1:10 Same Temps Cat fading, Air^.6 Small adjustments at low air settings can make a big difference.
2:20 Stove 425, Probe 420, Air+ .9 Only the Hedge half-round still retains its shape as it coals.
3:30 Stove 450, Probe 420
4:00 Stove 440, Probe 450 Cat glowing.
4:20 Stove 425, Probe 425 Cat black.
4:45 Stove 370, Probe 400
For some unknown reason, I have no more numbers on this burn. 🚮🥴

The next burn was all hard Maple, and another partial load. Stove was almost out, but still enough coals to start.
0:00 Stove 100, Probe 100, Air 2
:05 125, 220, Air -1.25
:10 130, 400, Air -1.1
:14 130, 420, Air -1.0 Closed bypass. Flame, cat glowing.
:18 Flame intermittent, cat part dim.
:20 200,400 Flame solid, cat all dim.
:23 240, 400, Air -.75 Flame solid, cat all bright.
:25 270, 390 No flame, cat medium glow.
:30 300, 390
:33 325, 400, Air -.5 Cat medium.
:40 400, 420 Cat bright.
:50 460, 450 Cat very bright.
1:00 500, 475 Cat bright.
1:15 500, 475 Cat bright.
1:40 480, 420, Air +.75
2:00 440, 400 Cat low.
2:45 270, 290
3:45 230, 220, Air +1.1
4:15 240, 250