2025/26 VC performance discussion thread

[Smokey Da Bears]

This is how I do it. STT, I have 3 magnetics on it in 3 different positions. Don't ask me why...I trust the one on the griddle the most. The other 2 are cheap amazon ones and they just ended up there and I kind of like it so they've stayed there. But as you can see from the picture of the stove top, they all are reading around 500 right now. I do have an IR gun, I rarely use it. But I just scanned near all 3 of those magnetics and I'm getting readings from those locations between 460-520 degrees F. If I have a left to right burn going on, I'll see the left most magnetic hotter than the other 2 which then fades as the burn progresses. Vice versa if I have a right to left thing going on, but my stove seems to almost always burn left to right.

So yesterday it was warm here, in the 40s. And I did end up taking the time to sweep my chimney, mostly soot, not a lot. I also emptied my ash pan which we'll see if that comes back to bite me or not. I put the brand new catalyst in and decided I'd light a fire this morning which I did around 5am. Colder here today in the 20s and windy. The new Cat lit off like a rocket and scared the poop out of me. The Auber was counting up by like 30 and 40 degrees at a clip which I hadn't seen in a long while. I thought ohh great, here we go - I'll be emailing midwest hearth by the end of the week. But she trailed off and hung out in the high 1200s and I was able to relax. I've been running some smaller loads today (3-4 medium splits) in consideration of that ash pan and a brand new cat. I'll probably put in a similar sized load in after dinner tonight but I'm not expecting that to heat all night and the oil will take over at some point. Stove glass is a bit boogered up but it'll either burn off or I'll clean it tomorrow.

 

[dmccoole]

Thinking the stove has been going well with the cold air so far this December, I had an interesting over night burn and afternoon burn today.

Ash pan is full, I emptied the box 2 days ago. New ceramic cat about 1 month old. Outside temps in the 20s with winds 20 mph.

At 9pm, I loaded the stove 3/4 full of med/large dry maple on a hot reload. At 1000, I turned primary down to 50%, at 1200 I turned it down to 10% open and let it go for the night. All seemed well at 11pm. I woke at 3am and noticed the cat temp was 374. So I went and checked. Stove was all black charcoal. I tried to add another split thinking it might all crumble, but had to push the split in as the box was still quite full. I turned the primary up to 30%, in a few minutes the cat hit 800 and I went back to bed. My wife got up at 6am and the cat was at ~600, she opened the bypass, burned off the glass, added a few splits and closed the bypass.

Why did the temp crash but still have a full charcoal load in the box? I've not had that happen before.

I let the wood in the stove burn down today, This afternoon I wanted test out a full load as I typically only do 3 splits at a time during the day. At 2:20pm I loaded the stove at least 3/4 using the same med/large dry maple on a hot reload. I tested a fresh split, the middle was 14.5%, closer to the ends was < 14%. Within 5 minutes the cat hit 1000, I turned the primary down to 50%. A few minutes later the cat hit 1200, I turned the primary down to 10% open. The cat continued to climb over the next 30 minutes. It hit 1600, so I closed the primary. Cat continued to climb. About an hour into the burn, the cat hit 1684 and then over the next 5 minutes it went down to 1660. I thought I was in the clear, but then over the next 5 minutes it quickly rose to 1702. STT 510. It then quickly dropped in 8 minutes to 1500 at which time the stove started back puffing. At 1450, I turned primary up to 50% and it stopped back puffing. STT 550. Cat continued a steady drop and at 6:30pm it was at 600 and the box was mostly burned down. I then added 3 more splits. So a 4 hour burn time.

Did I not learn my lesson and I should have left the primary at 10% open? Choking it down causes more smoke which causes the cat to rise. But then when the temp was coming down to 1500 why did it start back puffing?

Is the wood too dry?

Whatever is feeding or not feeding air to the cat is still a mystery! I can clearly hear the cat accelerating like when you open the door and the fire surges.

Two similar burns but two very different results.

 

[arnermd]

Thinking the stove has been going well with the cold air so far this December, I had an interesting over night burn and afternoon burn today.

Ash pan is full, I emptied the box 2 days ago. New ceramic cat about 1 month old. Outside temps in the 20s with winds 20 mph.

At 9pm, I loaded the stove 3/4 full of med/large dry maple on a hot reload. At 1000, I turned primary down to 50%, at 1200 I turned it down to 10% open and let it go for the night. All seemed well at 11pm. I woke at 3am and noticed the cat temp was 374. So I went and checked. Stove was all black charcoal. I tried to add another split thinking it might all crumble, but had to push the split in as the box was still quite full. I turned the primary up to 30%, in a few minutes the cat hit 800 and I went back to bed. My wife got up at 6am and the cat was at ~600, she opened the bypass, burned off the glass, added a few splits and closed the bypass.

Why did the temp crash but still have a full charcoal load in the box? I've not had that happen before.

I let the wood in the stove burn down today, This afternoon I wanted test out a full load as I typically only do 3 splits at a time during the day. At 2:20pm I loaded the stove at least 3/4 using the same med/large dry maple on a hot reload. I tested a fresh split, the middle was 14.5%, closer to the ends was < 14%. Within 5 minutes the cat hit 1000, I turned the primary down to 50%. A few minutes later the cat hit 1200, I turned the primary down to 10% open. The cat continued to climb over the next 30 minutes. It hit 1600, so I closed the primary. Cat continued to climb. About an hour into the burn, the cat hit 1684 and then over the next 5 minutes it went down to 1660. I thought I was in the clear, but then over the next 5 minutes it quickly rose to 1702. STT 510. It then quickly dropped in 8 minutes to 1500 at which time the stove started back puffing. At 1450, I turned primary up to 50% and it stopped back puffing. STT 550. Cat continued a steady drop and at 6:30pm it was at 600 and the box was mostly burned down. I then added 3 more splits. So a 4 hour burn time.

Did I not learn my lesson and I should have left the primary at 10% open? Choking it down causes more smoke which causes the cat to rise. But then when the temp was coming down to 1500 why did it start back puffing?

Is the wood too dry?

Whatever is feeding or not feeding air to the cat is still a mystery! I can clearly hear the cat accelerating like when you open the door and the fire surges.

Two similar burns but two very different results.

Welcome to the nightmare..... I empathize completely, I have experienced the same over the years. Might be time to call a priest.

• Near full box of charred wood: I have had this happen before, but it is pretty rare. I do not know why.... I think typically it happens on low draft days.
• Backpuffing with Cat > 1500: this happens to me quite frequently, in fact it is happening right now.... I do not know why.
  • A theory: Maybe there is so much hot smoke going through the cat and secondary passages that the pressure in the primary box is not low enough to draw enough air in consistently?
• Wood too dry?: I doubt it. 14% seems fine to me, but @Woodsplitter67 is my go to expert on wood drying....
• Cat Noise: There is a distinctive combustion noise that many have reported hearing when cat temps run away. For me it has been a very reliable indicator, if I hear the noise it is going to be a hyper active burn.... no noise and it will be nice and easy.
  • I suspect the noise may be related to my theory above, maybe the noise indicates elevated gas velocity in the secondary combustion and thus more pressure drop through the cat?

Sadly I do not have the answers we all seek.... would be really nice if VC would explain it. The inconsistency is maddening.

 

[arnermd]

If I remember correctly @arnermd has a STT probe that runs a little cooler, I could be wrong but I think that was the case. @Smokey Da Bears, what does your STT typically run at when you're cruising? When I'm cruising my STT is usually about 475-500 with the Auber TC-K-MAG probe but an IR gun says that range is 575-625. So which one is right?

Wow! What a memory! You are correct that my STT reads on the low side. Since last year though I have calibrated it with my IR gun and a bimetal (which both agree within ~30F) and I now correct the reading in my spreadsheet. The legend says "Corr Griddle" which is short for corrected. So the temps in the plot should be accurate as is. I have found a lot of temp variation across the griddle though depending on what kind of burn is happening. I have found variations of 100F between left, right and center as well as front to back.....

 

[AsylumResident]

Things have been going pretty well so far this year. I've let the ash pan fill up and haven't put more than 3 splits in at a time so the cat hasn't had the chance to run away on me. Today the high is 1 and I don't plan to be anywhere so I may load er up and see how it goes.

So far the most exciting part of this year is my 10 year old son has taken quite the interest in the whole process of the stove. He's been starting it, loading it, and watching the thermometers. Having him involved in this hadn't even crossed my mind before.

 

[Woodsplitter67]

Welcome to the nightmare..... I empathize completely, I have experienced the same over the years. Might be time to call a priest.

• Near full box of charred wood: I have had this happen before, but it is pretty rare. I do not know why.... I think typically it happens on low draft days.
• Backpuffing with Cat > 1500: this happens to me quite frequently, in fact it is happening right now.... I do not know why.
  • A theory: Maybe there is so much hot smoke going through the cat and secondary passages that the pressure in the primary box is not low enough to draw enough air in consistently?
• Wood too dry?: I doubt it. 14% seems fine to me, but @Woodsplitter67 is my go to expert on wood drying....
• Cat Noise: There is a distinctive combustion noise that many have reported hearing when cat temps run away. For me it has been a very reliable indicator, if I hear the noise it is going to be a hyper active burn.... no noise and it will be nice and easy.
  • I suspect the noise may be related to my theory above, maybe the noise indicates elevated gas velocity in the secondary combustion and thus more pressure drop through the cat?

Sadly I do not have the answers we all seek.... would be really nice if VC would explain it. The inconsistency is maddening.

Iv had wood.in my stove as low as 3% and it burned fine.. it was a hot fire but not out of control back puffing and super high cat temps

 

[Woodsplitter67]

Thinking the stove has been going well with the cold air so far this December, I had an interesting over night burn and afternoon burn today.

Ash pan is full, I emptied the box 2 days ago. New ceramic cat about 1 month old. Outside temps in the 20s with winds 20 mph.

At 9pm, I loaded the stove 3/4 full of med/large dry maple on a hot reload. At 1000, I turned primary down to 50%, at 1200 I turned it down to 10% open and let it go for the night. All seemed well at 11pm. I woke at 3am and noticed the cat temp was 374. So I went and checked. Stove was all black charcoal. I tried to add another split thinking it might all crumble, but had to push the split in as the box was still quite full. I turned the primary up to 30%, in a few minutes the cat hit 800 and I went back to bed. My wife got up at 6am and the cat was at ~600, she opened the bypass, burned off the glass, added a few splits and closed the bypass.

Why did the temp crash but still have a full charcoal load in the box? I've not had that happen before.

I let the wood in the stove burn down today, This afternoon I wanted test out a full load as I typically only do 3 splits at a time during the day. At 2:20pm I loaded the stove at least 3/4 using the same med/large dry maple on a hot reload. I tested a fresh split, the middle was 14.5%, closer to the ends was < 14%. Within 5 minutes the cat hit 1000, I turned the primary down to 50%. A few minutes later the cat hit 1200, I turned the primary down to 10% open. The cat continued to climb over the next 30 minutes. It hit 1600, so I closed the primary. Cat continued to climb. About an hour into the burn, the cat hit 1684 and then over the next 5 minutes it went down to 1660. I thought I was in the clear, but then over the next 5 minutes it quickly rose to 1702. STT 510. It then quickly dropped in 8 minutes to 1500 at which time the stove started back puffing. At 1450, I turned primary up to 50% and it stopped back puffing. STT 550. Cat continued a steady drop and at 6:30pm it was at 600 and the box was mostly burned down. I then added 3 more splits. So a 4 hour burn time.

Did I not learn my lesson and I should have left the primary at 10% open? Choking it down causes more smoke which causes the cat to rise. But then when the temp was coming down to 1500 why did it start back puffing?

Is the wood too dry?

Whatever is feeding or not feeding air to the cat is still a mystery! I can clearly hear the cat accelerating like when you open the door and the fire surges.

Two similar burns but two very different results.

Me personally I probably would have done nothing. Just let it run it's course

 

[Turbo89]

use the boil water test, if practical. 212 F degrees

That’s the best way to check, boiling water and a bucket of ice water!

 

[arnermd]

Yesterday I switched from my ceramic cat back to my old tired metal cat (has about 1 season on it). Notice the difference in the two burns.....

• Ceramic Cat: this was a 3/4 load, cat rocketed up to 1600 and stayed there for an hour..... Flue gas temp hit 800+
  • Temp dropped a lot after reducing the air, I probably closed it down too fast, but I had sh*t to do!
  • I did close my key damper to bring draft down from 0.15 to 0.8 iwc at 8:10. It helped for a bit but the temps slowly climbed back up to 1600+ before relenting.
• The metal cat run was a full load, took a lot longer to come up to temp and it only saw 1600 for a short period of time. I would call this a good burn.