Hearth brutha hooks me up; Cat probe ready to go!

[Woody Stover]

Todd, longtime hearth.com member and former Keystone burner, bought a secondary-burn stove for his new place. He saw me post (maybe a hundred times) about being way late on installing a digital cat probe in my Keystone, which I've been burning for many years. Maybe he thought "If I give him my old probe, maybe he'll finally get off his butt and do it." 😆 It's an Auber AT200 digital termometer kit, with two thermocouples! 🤗 Embodying the helpful, generous spirit that is the basis of the community here at hearth.com, Todd is indeed the man! My hat is off to you, sir!
It's been quite a few weeks since he shipped it to me (no charge, no less😃) but I finally got 'er done today. In my defense, I was feeling pressure since I'm still scrambling to get dry wood for two SILs for next season. But now that I've found lots of stuff that I think I can get dry in time, or already is dry, I'm feeling better about the situation and feel like I don't have to go get wood every day.
All the cards fell right for getting that probe installed today: Warm day where I could let the stove go out, me having a cold, so being a bit tired to go out and get wood, and it was windy so going in the woods coulda been unsafe. So I went with the probe install.
When I opened Todd's package, I saw that in addition to the 10" cat probe, he had also included the washer-probe sensor for single-wall pipe. 👍
First I had to take off the rear heat shield on the stove, that reflects radiant heat off the back of the stove from going into the exterior masonry chimney and heading outside. Once that was out of the way I could remove the old analog Condar probe, which can't carry the cat temp all the way back to the dial, so ends up being more of a flue exit probe. The hole for it is on the back of the stove, which is flush with the front of the fireplace opening, so was kinda hard for me to read until I remembered I had a small telescoping mirror.
First I hooked the washer probe behind a screw securing the tee to the liner. I wanted to put in under the back screw, but that seemed hard to turn when I started removing it, leading me to think it might be hard to get the screw back in again, so I opted for another screw on the side.

Then I threaded the thermocouple in, roughly in position over the exhaust side of the cat. Todd said he thought he mighta had to open up the probe hole in the back of his stove but that wasn't the case with mine, probe slipped right in, no problem. He had some foil wrapped around the base of the thermocouple, to get a more secure fit and hold it in place. I think I've got the probe about 1/2" or so above the cat face, and in the middle of the cat, front to back. Side to side, it's toward the right end of the cat, since that's the side it comes into the stove on, right of the rear-exit flue. Looked like Todd had bent the probe slightly, as I did with the analog probe, so that it wouldn't be real close to the end of the cat, but a little more toward the middle, anyway.
Not sure it will stay put where I've got it right now, but we'll soon see..


So, Todd, what do I do now? 😆 How did you use the probe...get to a certain cat temp (like 500?) and then you knew you were good to close the bypass?
And thanks once again for your generosity! Hmmm, now what could I send you...a load of Bodark, maybe?
I haven't put the heat shield back on yet, in case I have to make adjustments..

 

[Todd]

It’s about time! 😂 your going to have to experiment to see what works best. As far as I can remember I was engaging the cat around 500 and keeping the air around 2 for a bit before turning down to desired setting. Maybe look at some of our old private conversations if they’re still in there? I don’t think your Bodark would burn as good as my feather lite Aspen and Jack Pine! 😂

 

[Woody Stover]

😆 Yeah, I'm not always the speediest when it comes to getting stuff done--just ask my wife. 😏 But this job was never far from the top of the list, and it looks like I've got some good burning weather on tap for more experimenting, checking out the washer thermocouple on the flue etc. 👍
I'm not sure about how the high-output woods burn in a secondary stove, as I've supplied the T5 burner with mainly Red Maple that I could get dry in time. But I've also had some White Ash and Oak, which she said takes off slower in a new load so that getting too much wood burning early is less of an issue. I know (as you do) that high BTU woods in a cat stove result in long, high temp burns that allow for extended heat production without having to do much but open the air a bit when the load finally gets to the coaling stage.
Looks like I'll really be able to fine-tune the running of the cat with the info that the probe is providing. In the first burn with it last night, I ran the probe to 500, closed the bypass and got a glowing cat immediately. It started to drop a bit as the faster-burning starter splits were consumed, and the fire tried to eat into a huge gnarly White Oak split that was in the back. I could almost instantly see the effect that opening or closing the air had on the cat temp, so I left the air open a bit more to allow the fire to get the White Oak split gassing sufficiently.
This is more in line with realistic cat temps I expect to see.

I'm thinking I'll be able to use this to keep the cat burning as long as possible which should result in a cleaner burn among other things..
The fun has just begun! 🤓

 

[Woody Stover]

Interesting.. At the end of the burn there were a couple of White Oak splits still retaining their shape, and from the stage of coaling I would have guessed there were no more volatiles. But checking the meters, stovetop was 275 and probe was 575, seeming to indicate that the cat was still active. Maybe the dense woods still have more solid wood in the center, despite looking on the outside like they're about tapped out? I coulda rapped them with a poker hook and see if they woulda split apart, and what was inside, but I didn't think of that 'til later. This is the kind of feedback you don't get from a stovetop meter, even it it's positioned over the cat.
Now, maybe the analog cat (flue) probe somewhat indicated the same, since it was pretty late in the coaling stage before the stove and analog probe temps became close to the same temp. But I just figured that was because the probe, being inside the box, was getting more direct heat than the stovetop meter was and that the same would happen even if all volatiles were gone and only coals were burning down the rest of the way. Maybe I can get a better handle on what's happening as I observe more.

 

[huauqui]

This should be fun, I have my popcorn ready. Can't wait to read how things are going with this. This is also why I love these forums. Some of the best people out there.

 

[begreen]

I don't think the surface probe's wiring is meant for this high temp environment. It would be better to purchase a probe from Auber and replace the analog probe. They are inexpensive. Or has this already been done?

 

[Woody Stover]

I don't think the surface probe's wiring is meant for this high temp environment. It would be better to purchase a probe from Auber and replace the analog probe. They are inexpensive. Or has this already been done?

I had the anolog Condar cat probe going in through the hole meant for it, in the back of the stove. But as I've said, it can't transmit true cat temp back to the dial over the 8" length, so it functions as a flue meter of sorts, getting to about 500-600 or so before I close the bypass. Now, it's off to the side a bit as shown in the pic, so probably isn't reading as high as if it were in the direct exhaust stream. You can still run the stove with it, though.
I haven't had a chance to see what's available in a probe thermocouple for in the tee or liner. but thought that would give more immediate feedback than the washer. In any case, I'd need another thermometer to plug in an addition thermocouple.
Todd sent me the AT200, and both the 10" cat probe and the washer thermocouple. I too wondered about the washer cable, but looked it up on the Auber website and it looks like no problem. Oops, forgot to post that original pic of what was in Todd's package..

 

[DBoon]

At the end of the burn there were a couple of White Oak splits still retaining their shape, and from the stage of coaling I would have guessed there were no more volatiles. But checking the meters, stovetop was 275 and probe was 575, seeming to indicate that the cat was still active. Maybe the dense woods still have more solid wood in the center, despite looking on the outside like they're about tapped out?

Hi Woody Stover, I suspect your white oak is not much different than my bitternut hickory in that there seems to be a second stage of the off-gassing with these really dense woods, and it's not uncommon with a load of big hickory splits (with the Keystone or my old tube stove) to get a second temperature rise. My tube stove would just go nuclear for 20 minutes or so, whereas my cat stove will drop from 550 to maybe 475, then go back up to 500-520 for another 20-30 minutes before finally dropping rapidly to 350 once the final off-gassing occurs.

 

[Woody Stover]

Right, these burns aren't a linear progression; They all do their own thing, depending on what woods are used, how they're loaded, how the fire happens to burn, and a bunch of other factors too involved to figure out.
After the front went through this afternoon and temps started to drop, I fired a load in a barely-warm stove. I had mostly White packed in, then a good-sized Maple split in the front to kick it off. I kept flame going after closing the bypass to make sure the Oak was catching well, and it was a slow gain in cat temp over a period of time. The cat eventually got glowing pretty brightly and it looked like plenty of Oak was burning so I cut the air to under 1. After a while, cat temp started dropping. I think that was due to the Maple split finally breaking in half, and maybe taking more of the available oxygen, because where the Maple had broken in half, it was glowing pretty good.
Really, I wouldn't have had to cut the air at all probably...cat wasn't glowing super-bright and was only low 1200 temps. So I'm going to try a more hands-off approach on a few burns instead of micro-managing, and try just letting the burn take its course, just opening the air up a bit at the end to keep the coals throwing good heat until it's time to reload.

 

[Woody Stover]

The White blocks I had stacked against the back wall finally fell forward and flamed up, producing a pretty blue-flame fire. 🙂

 

[Woody Stover]

Oh, cool. I clicked the three-dot menu (or settings) on that vid and slowed it down to . 5 speed--really gives a good look at the flames.
Probably everybody knows more than me about YouTube. 😆

 

[Woody Stover]

I don't think the surface probe's wiring is meant for this high temp environment.

As I said, I think the probe is OK, but reading again the instructions for the meter itself, they want operating range 0-100°F. I know that, generally, heat is an enemy of electronics but didn't really make the connection. 😴
I moved it around to the side of top brick under the mantel.

 

[begreen]

As I said, I think the probe is OK, but reading again the instructions for the meter itself, they want operating range 0-100°F. I know that, generally, heat is an enemy of electronics but didn't really make the connection. 😴
I moved it around to the side of top brick under the mantel.
View attachment 310629

I wasn't referring to the Auber unit. The washer-style probe end is designed for surface reading on the outside of the stove. The concern is about the wire inside the stove. A probe-type hi-temp thermocouple is what is used inside the stove where only the probe enters the stove, not the probes connecting wiring.

 

[Woody Stover]

The White blocks I had stacked against the back wall finally fell forward and flamed up, producing a pretty blue-flame fire. 🙂

I wasn't referring to the Auber unit. The washer-style probe end is designed for surface reading on the outside of the stove. The concern is about the wire inside the stove. A probe-type hi-temp thermocouple is what is used inside the stove where only the probe enters the stove, not the probes connecting wiring.
View attachment 310633

Right, "on the surface of the pipe or stove." Not sure if I used a #10 screw, though..
In post#1 pics, you'll see that the washer is mounted to the pipe. In post#7, you see that Todd sent both the washer probe and the 10" cat probe--No wires inside the stove.

 

[Highbeam]

That keystone is a handsome stove.

 

[begreen]

That keystone is a handsome stove.

Yes, the Keystone and the Palladian have always been my favorite Woodstocks.

n post#1 pics, you'll see that the washer is mounted to the pipe.

Ah you are right, I was seeing something very different with that picture until just now when I enlarged it.

 

[Woody Stover]

That keystone is a handsome stove.

It was destiny that I get the stove, since as begreen once pointed out, that's a keystone above the lintel. 😏

 

[Todd]

So how’s it performing? Have you had time to burn it hot and see higher cat temps? I don’t think I ever remember mine going over 1600. With a good cat glow I think it was 1200-1400.

 

[Woody Stover]

So how’s it performing? Have you had time to burn it hot and see higher cat temps? I don’t think I ever remember mine going over 1600. With a good cat glow I think it was 1200-1400.

It's working great, thanks again Todd! I think it got up to 1400 once...several 1200s. Been closing the bypass at around 500 or so, then keeping some flame heat going to the cat for a solid light-off, and to get more wood gassing.
Last few nights, been burning partial chill-buster loads. I've put in maybe four splits on those, White Oak, Mulberry and a hard Maple to kick 'em off. It's been kinda hard to get the cat light strong when I've only got a few splits in there, and not much wood gassing. Couple nights ago I left after starting a little load, and my wife texted me that the stovetop had only gotten to a little over 400.
I did a similar load last night but burned it in a little harder to get more gassing, and it peaked out at 500 stovetop. Cat probe went to 1100, a dull red glow that time.
The probe is a little too long to be able to put the rear shield back on the stove with the stock bolts/spacer sleeves, so I just hung it in place with a piece of annealed wire draped over the top of the tee snout and stuck through the bolt holes in the shield. I could get longer bolts/sleeves, but this wire setup is sure a lot easier when taking the shield off and on.

It's 76 here right now--Crazy, I tellya! 😵 Not great weather for burn experiments, but it's getting wood drier, so there's that! 👈
But it's going to 42 tonight with wind, so I'll probably light another chill-buster load later this evening.
It's been informative and fun so far with the cat probe, it's great to finally be onboard! Like begreen has said, the probes change the way you run the stove. I'm at the beginning of the curve, though, still lots to observe and learn. 🤔

 

[Todd]

76 sounds so nice but I’d hate to see what happens at those temps with our 30” of snow we have on the ground. Had another 6” today. 😒

Yeah that probe should help a lot when it comes to cat engagement with your setup. Glad someone could put it to use again.

 

[Woody Stover]

30” of snow we have on the ground. Had another 6” today. 😒

30", wow! Do you get lake effect snows there, or are you too far from the lake for that?

 

[Todd]

30", wow! Do you get lake effect snows there, or are you too far from the lake for that?

We get some lake effect but the wind has to be just right. Most of the snow this year was system snow. Way above normal this year.

 

[Woody Stover]

Last night I loaded 3/4, and used some Cherry, with only one dense split..maybe a BL? Cherry got going easy and gassed nicely. I've been leery of using it; My glass was gunking a bit, and both the Cherry and hard Maple I'm using now sat in rounds for a couple or three years before I split it over the summer. Both of those may need another summer drying in split form, not sure. Might be running into a damp one now and then, and that could be complicating operation a bit. Come to think of it, the BL sat in rounds for five years, but was also just split last summer, so it maybe could use a bit more time in the stack. I split that pretty small, though, and with five years in rounds you'd think it'd have to be drier than the Cheery and hard Maple at two years.
I have some Red Maple out there that's really dry, stacked a couple summers, so when I reload the on-deck circle, I'll bring some of that, and some White Oak that's been split five years or so.
Anyway, last night's load with mostly Cherry started and burned nice, with cat temps around 1100 and stove 500.
We are in for a couple cool, breezy nights with lows in the 30s.. full-load time. 👉

 

[Woody Stover]

A little over an hour ago I loaded pretty much full, mainly Cherry plus a smaller BL and some other split..possibly Red Elm? Once the bypass was closed, the burn settled in and I was off the timer, I looked over after a time and a top split had rolled forward into the andirons and was flaming up pretty good. Cat probe was like 1240 and the cat glowed about medium. I cut the air a little, flame subsided a good bit, and even though the cat started glowing more brightly, temp dropped under 1200 fairly quickly. Flame heat theory holds water I guess.
Then after a while I looked over and had the "flame behind the cat screen" thing going on, cat bright. Probe temp was back up in the 1200s. I cut a little more air, flame behind the screen decreased and probe temp dropped again into the 1100s for a while, then headed back up. Cat was glowing about medium but then went up into the 1200s as the right side where the probe is started getting more smoke.
Now, about three hrs. in, I've got a little "cave" in there, with part of that split wedged against the andirons, and ash pan housing air glowing and eating the cavern in the bottom splits. Something different every time with these loads.

I guess I should work on the taxes a little more. I already got a nice break when I had to go for printer ink. 🤣 Well, I'll at least make a token effort yet tonight, anyway...😏

 

[Woody Stover]

37* and breezy here so I got a running start on the remnants from last night. 150 STT, 250 probe. Loaded mainly Cherry again, one semi-flat split White Oak in the middle of the bottom row, and a 3" round of something, not super-dense, top front. Maybe Red Elm? Several decent-sized coals left, I pulled them forward.
I opened the air, wood quickly caught and I burned it in for about 5 min. Probe was at 350 when I closed the bypass and kept flame going, air at about 2. Cat started to dimly glow in the back, about a minute later. After a couple more minutes I cut air to 1.5. Flame went out and cat quit glowing but the probe was 600 and climbing, so I just let it go. I might have been inclined to get the flame going again, if not for the probe information...gee, this makes running the stove a lot easier.
Probe is now 1247, air is cut to .9, and intermittent flame is floating in front of the cat screen. Life is good. ☺️