2024/25 VC performance discussion thread

[AsylumResident]

Have you tried running a higher air setting? I generally find I get lower temps with more primary air, typical overnight for me is 40 - 60% setting. The STT is hotter but the cat peaks are shorter.

Running with really low airflows gives you a longer, smokier primary burn and it creates a lot of fuel for the cat. So it effectively shifts the combustion load from the primary to the cat and leads to higher secondary temps for longer and low STT's. When I run low airflows my glass blacks out and if I open the griddle a crack I get a huge cloud of smoke out....

I found things are more controllable with higher airflows, but my metal cat is also peaking at 1550 - 1600 on a full load.

Yes, this year has all been with an air setting greater than 50%. It has been frustrating.

I have been running hotter with higher STT's than normal to see how it would go.

 

[Eman85]

It's been cold! 24/7 burning and using quite a bit of wood. I am now part of the don't empty the ash pan crowd. I have been building large heap of ashes in the box and the stove is more user friendly. I let the coals burn to ash and stir them and only dump the pan if there's enough in the box to fill it again. I leave the pan full and a fair amount in the box and load on top of the coals. I haven't opened my front doors in many weeks. Even when it warmed up for a few days weeks ago I built and lit the fire from the top. With as cold as it's been I'm going for more heat in the room and running the cat hot and when it drops I've been opening the air and keeping it hot. Even opening the air in the middle of the night when nature calls. Still getting 12hr burns out of a full load.

 

[Woodsplitter67]

So stove performance has been excellent. Its been cold here and we are really ripping through the wood. This will definitely be a season were we burn alot of wood. Last year Im pretty sure I barely burned 3 cords. This year Ill probably burn 4. Normally I sweep in January, mid season but with all of the snow on the roof Ill most likely not.

The house has definitely been warm getting it to 70. I did set the gas fireplace to turn on at 66 at night. I set the fireplace because the house cools at night with the stove getting low on coles. The fireplace keeps the house getting to cold and having to work the stove hard to get the temperature back up. Ths week Iv been burning the coals down some and raking the ash into the pan to keep it from building up.
Normally I load in the morning and turn the air all the way back and let it Cruise the rest ofthe day. Now its load it all the way up and set the air about halfway, then reload like 3ish.

This stove is an excellent heater, long burn times and throws heat. Im happy to have it

 

[U235]

So I’ll preface this by saying I admire everyone’s tenacity in the pursuit or mysterious discovery of extended burn times. What I do won’t work for most, but it might for some. I’ve found clean glass/refractory, no catalyst over temps, and heat my home needs with acceptable fuel usage. I’ve abandoned run time.

Catalyst/flue(internal)/griddle. Every 1-2 hours, I’ll drop a chunk of ash or locust on an ever-growing bed of coals with a handful of splinters and bark. Catalyst recovers and burn continues. My limiting factor is griddle temps. At ~575 from the thermocouple, I’m seeing 650-700 on magnetic stove top coil.

 

[AsylumResident]

So I’ll preface this by saying I admire everyone’s tenacity in the pursuit or mysterious discovery of extended burn times. What I do won’t work for most, but it might for some. I’ve found clean glass/refractory, no catalyst over temps, and heat my home needs with acceptable fuel usage. I’ve abandoned run time.
View attachment 335621
Catalyst/flue(internal)/griddle. Every 1-2 hours, I’ll drop a chunk of ash or locust on an ever-growing bed of coals with a handful of splinters and bark. Catalyst recovers and burn continues. My limiting factor is griddle temps. At ~575 from the thermocouple, I’m seeing 650-700 on magnetic stove top coil.

This is exactly my method this year.

 

[Eman85]

And just about the time you think you can control the beast!
Single digits this AM, ran with air open about 1/2 and the box had burned down pretty low by the time I reloaded. Loaded box about 1/2 and it was beautiful, cut air back to 1/2 and enjoyed all of the warmth. When it had burned down pretty good I opened the damper, cat about 800, and loaded a full box. Gave it a few minutes and engaged the cat, cat rose nicely and cut the air to 1/2 and it stabilized. Went out to get the mail and when I walked back in cat was off to the races, 1350 and climbing. No stopping this runaway train, tried air fully closed kept going opened air and it paused and then back off to the top to 1650. Air shut and we started the backpuffs past the griddle. Opened the bypass and let the cat drop and kept an eye on flue outlet which had gotten pretty high. Played the game of letting the cat dop as flue temps rose then flipping the bypass and the cat goes up as the flue temps drop. Finally got it where I wanted burning it like a smoke dragon with the air closed down.
I need to do some checking later today. I can hear and see the air flap close completely but see some flareups in the box. I might have developed an air leak somewhere. Still have a good ash base and the pan is loaded, thought I was really on to something.

 

[dmccoole]

Last night was stressful. Stove had been running great especially in these cold temps. Starting on Sunday I got into some maple I cut 2 years ago. It's dry but it's not the oak I've been running. Loaded the stove to the top at 10pm. The steel cat steadily climbed to 1600 at 1/4 primary and then started to come down. At 12:15 it started climbing again and was at 1725. The stove looked like it was back puffing so opened the primary for a second to let some of that gas out. Big puff of smoke and I quickly closed the primary fully. Then it really took off. Cat went to 1746 and the pipe went red hot. Griddle was 650, behind the griddle was 700. The cat temp stayed like that for about 10 minutes and then started dropping. The black pipe section in the pic is because I have a section of black pipe wrapped around where the stainless liner connects to the T coming out of the stove for aesthetics. My wife got the fire going this morning as she got up before I did. All seems ok with cat at 800 with a few splits. I'll let this burn down and then open it up to check out cat.

Learned 3 things:
1. I'm really liking the Aubor AW-TMB-Deluxe wifi monitor so I can monitor the stove remotely and receive alerts on my phone which is what got me up at 12:15.
2. Don't stuff the stove full of maple.
3. Don't play with the primary at high temps. In the past I've noticed when the cat hits say 1500 and I close the primary, the cat will take off quickly for a spell. Really seems counterintuitive.

Lastly,
I'm still unsure what controls the secondary air and how it allows the stove to take off like this.

Stay Warm!

 

[weee123]

Now THAT’S a night light. I guess this pic reinforces what they were talking about yesterday with not messing with the primary air.

 

[Eman85]

Since my overheat I haven't engaged the cat been running it like a basic stove. Plenty of heat and it did a nice overnight burn just like it always has. Plenty of coals this morning, threw a few splits on and it took off, turned the air down when the flue got hot and it's been cruising since.
I'm almost tempted to pull the cat and run it with the damper in bypass and no cat, I've never done that to see how it will burn.

 

[dmccoole]

Here's what my steel cat looks like after 1746 degrees. No frame warpage. Only one side dropped a little in the middle. I flipped it over and rotated it left to right. I cleaned out the ash and restarted a fire. Once I got a good bed of coals I added 3 medium splits. Once those lit and the griddle at 550, I closed the bypass. Cat lit right off and 15 minutes later it's at 636 and climbing.

I was able to get it back up to temp before the oil heat kicked on in the house. That's a plus.

I'm home during the day and typically add 2-3 med splits at a time like several of you stated. I'll keep doing that during the day and only add 1 or two more for the overnight burn until I get through this maple.

 

[Megunticook]

Since my overheat I haven't engaged the cat been running it like a basic stove. Plenty of heat and it did a nice overnight burn just like it always has. Plenty of coals this morning, threw a few splits on and it took off, turned the air down when the flue got hot and it's been cruising since.
I'm almost tempted to pull the cat and run it with the damper in bypass and no cat, I've never done that to see how it will burn.

Last night was stressful. Stove had been running great especially in these cold temps. Starting on Sunday I got into some maple I cut 2 years ago. It's dry but it's not the oak I've been running. Loaded the stove to the top at 10pm. The steel cat steadily climbed to 1600 at 1/4 primary and then started to come down. At 12:15 it started climbing again and was at 1725. The stove looked like it was back puffing so opened the primary for a second to let some of that gas out. Big puff of smoke and I quickly closed the primary fully. Then it really took off. Cat went to 1746 and the pipe went red hot. Griddle was 650, behind the griddle was 700. The cat temp stayed like that for about 10 minutes and then started dropping. The black pipe section in the pic is because I have a section of black pipe wrapped around where the stainless liner connects to the T coming out of the stove for aesthetics. My wife got the fire going this morning as she got up before I did. All seems ok with cat at 800 with a few splits. I'll let this burn down and then open it up to check out cat.

Learned 3 things:
1. I'm really liking the Aubor AW-TMB-Deluxe wifi monitor so I can monitor the stove remotely and receive alerts on my phone which is what got me up at 12:15.
2. Don't stuff the stove full of maple.
3. Don't play with the primary at high temps. In the past I've noticed when the cat hits say 1500 and I close the primary, the cat will take off quickly for a spell. Really seems counterintuitive.

Lastly,
I'm still unsure what controls the secondary air and how it allows the stove to take off like this.

Stay Warm!

Who knew wood burning was such an adrenaline sport?

Damn, that glowing stove pipe is impressive/terrifying! Haven't seen anything quite like that before (outside of a foundry, that is).

My Encore 2550 has been running very well this winter (23rd year). I suspect I have a small air leak where the top joins one of the sides, so I'm being a bit cautious with it--I never load it to the hilt under any circumstances and for overnight burns just a couple large splits of red oak will generally leave coals for the morning rekindle.

Will bite the bullet this summer and do a full teardown/rebuild. Makes me nervous not being able to really shut things down with the primary air control when needed. I can knock the flames way back with it fully closed but can't extinguish them fully. I'm sure if the firebox was right full of dry wood or I had a bunch of smaller stuff in there it would run away on me.

Hope everyone's staying warm and enjoying their stoves. Been quite a cold snap here in Maine this week (-2 the other morning). Great weather for splitting firewood.

 

[Woodsplitter67]

stove performance

 

[Crab]

Who knew wood burning was such an adrenaline sport?

Ain't that the truth

 

[Woodsplitter67]

Filled the box this morning and let it rip.. hers a picture of sustained secondary burs in the box.. cat was 1422

 

[arnermd]

Decided to start it up for the first time in a year, everything is still working smoothly.

Impressive you can keep cat temps that tight. I can tell the thing wants to go nuclear by all the dithering. I think your control loop could definitely benefit from some tuning. Loosen up the cat limits a bit and go to a proportional control loop with less gain.

Very impressive.

 

[arnermd]

Last night was stressful. Stove had been running great especially in these cold temps. Starting on Sunday I got into some maple I cut 2 years ago. It's dry but it's not the oak I've been running. Loaded the stove to the top at 10pm. The steel cat steadily climbed to 1600 at 1/4 primary and then started to come down. At 12:15 it started climbing again and was at 1725. The stove looked like it was back puffing so opened the primary for a second to let some of that gas out. Big puff of smoke and I quickly closed the primary fully. Then it really took off. Cat went to 1746 and the pipe went red hot. Griddle was 650, behind the griddle was 700. The cat temp stayed like that for about 10 minutes and then started dropping. The black pipe section in the pic is because I have a section of black pipe wrapped around where the stainless liner connects to the T coming out of the stove for aesthetics. My wife got the fire going this morning as she got up before I did. All seems ok with cat at 800 with a few splits. I'll let this burn down and then open it up to check out cat.

Learned 3 things:
1. I'm really liking the Aubor AW-TMB-Deluxe wifi monitor so I can monitor the stove remotely and receive alerts on my phone which is what got me up at 12:15.
2. Don't stuff the stove full of maple.
3. Don't play with the primary at high temps. In the past I've noticed when the cat hits say 1500 and I close the primary, the cat will take off quickly for a spell. Really seems counterintuitive.

Lastly,
I'm still unsure what controls the secondary air and how it allows the stove to take off like this.

Stay Warm!

My theory on why closing the primary increases cat temps....

You have a thermal mass in there that is outgassing and making visible flame, when you reduce primary there is not enough oxygen to sustain the primary fire so what you get is a lot of smoke. That smoke encounters oxygen and a hot cat and combusts there. Temps go up until the thermal mass cools down and stops making so much smoke.

I think if you reduce the air slowly, in smaller bits overtime it will mitigate this.

What I can't explain is why sometimes I close the primary down and the cat temp goes up and stays up.... for hours.

 

[dmccoole]

My theory on why closing the primary increases cat temps....

You have a thermal mass in there that is outgassing and making visible flame, when you reduce primary there is not enough oxygen to sustain the primary fire so what you get is a lot of smoke. That smoke encounters oxygen and a hot cat and combusts there. Temps go up until the thermal mass cools down and stops making so much smoke.

I think if you reduce the air slowly, in smaller bits overtime it will mitigate this.

What I can't explain is why sometimes I close the primary down and the cat temp goes up and stays up.... for hours.

Makes sense but what controls the secondary air? I would expect that if it's too hot, the secondary air would throttle down and not allow it to go nuclear. The oxygen has to be coming from some where as the primary is closed.

 

[arnermd]

Makes sense but what controls the secondary air? I would expect that if it's too hot, the secondary air would throttle down and not allow it to go nuclear. The oxygen has to be coming from some where as the primary is closed.

Right... so this where I would love the hear from VC with regards to the design approach. As you know there is no active control of the secondary air so my guess is they designed the secondary combustion to run lean (excess air) all the time. The way they control Cat temps is buy reducing the fuel (smoke) which gets controlled by the thermostat which controls primary air. If you have a clean burning primary the cat temps will be low, if your primary is smokey then cat temps will be high. This explains why I tend to see higher cat temps with low griddle temps.

The oxygen for the secondary burn is always there as there is no active control. I suspect that the air mass flow might be reduced a little as the air is heated it becomes less dense and thus you get less oxygen going through the same size passages.

The oxygen for the primary burn comes through the primary flapper, unless it is closed then it comes through the epa hole in the bottom of the stove under the ashpan. That hole is also uncontrolled so it always allows some airflow for primary combustion. Plus any leaks we might have in the firebox.

All this is just my opinion of course.....

 

[dmccoole]

Thanks arnermd That all sounds logical. I was thinking there was some sort of steel spring coil that opens and closes a secondary flap somewhere. I read something like that about another stove, sometimes when it gets too hot the steel spring starts to go past the closed position and starts to open the flap again.

I've read many of your graphs over the last couple of years and can't imagine going through that so frequently. All I know is that I don't want to ever see my stove pipe glowing red hot again. I'm keeping the maple to 2-4 splits per reload and I'm getting through the stack. I'll make sure to keep a separate pile of oak for over night burns from now on. I'm on my 5th year with this stove and still learning! I had 25 years with my previous woodstove and never had these types of issues.

 

[arnermd]

Thanks arnermd That all sounds logical. I was thinking there was some sort of steel spring coil that opens and closes a secondary flap somewhere. I read something like that about another stove, sometimes when it gets too hot the steel spring starts to go past the closed position and starts to open the flap again.

I've read many of your graphs over the last couple of years and can't imagine going through that so frequently. All I know is that I don't want to ever see my stove pipe glowing red hot again. I'm keeping the maple to 2-4 splits per reload and I'm getting through the stack. I'll make sure to keep a separate pile of oak for over night burns from now on. I'm on my 5th year with this stove and still learning! I had 25 years with my previous woodstove and never had these types of issues.

The older VC stoves had secondary air control. If I had it to do all over again I would buy one of those used and rebuild. My buddy has two and he said the cat temps are really stable. In those stoves the secondry air never mixes with the primary combustion, it is all separated. Makes a lot more sense to me.....

Hope you got some use out of my plots and posts.... I am on year 12 I think with this stove and it has never run right, very inconsistent. Some days I can't get the cat hot no matter what I do, other days it goes stright to 1400 in 10 minutes.... crazy.

I have never burned maple, but I know ash tends to overheat my cat more so than red oak.

Somehow @Woodsplitter67 has it figured out.... most of the time. lol. He is my hero.

 

[Woodsplitter67]

The older VC stoves had secondary air control. If I had it to do all over again I would buy one of those used and rebuild. My buddy has two and he said the cat temps are really stable. In those stoves the secondry air never mixes with the primary combustion, it is all separated. Makes a lot more sense to me.....

Hope you got some use out of my plots and posts.... I am on year 12 I think with this stove and it has never run right, very inconsistent. Some days I can't get the cat hot no matter what I do, other days it goes stright to 1400 in 10 minutes.... crazy.

I have never burned maple, but I know ash tends to overheat my cat more so than red oak.

Somehow @Woodsplitter67 has it figured out.... most of the time. lol. He is my hero.

Whats up my friend.. I haven't been with my ups and downs. So far this burning season I had 1 major spike going over 1700 degrees and my temperature probe went bad.. man was that annoying with the alarm going off. I.had a spare so I put that on and been good ever since and somehow I killed a steel cat..

As a side note I dont think that my stove has run this long without going cold more then once.. its a new Woodsplitter67 record. This stove overall has .what I think.. run well all heating season. I've been out back splitting.. well because thats wat a Woodsplitter67 does.

 

[Woodsplitter67]

I thought this fireplace was super cool.. I said to my wife we need to put this in our 5000 sqft log cabin in the mountains when we build.it

 

[Eman85]

Good luck to those trying to figure out the secondary air system on a VC stove. Mine is old and I have never been given a clear explanation of what it does. I've replaced the probe/coil and it still closes when first heating up and then opens when the cat gets very hot. My guess is that it's supposed to cool the cat and lean out the mixture so there isn't as dense of an amount of combustibles in the smoke. All of that said the cat will still go crazy high.
I can't say I've ever run my stove continuously as much as I have this year since living in this house. Burning through a lot of wood.

 

[arnermd]

Whats up my friend.. I haven't been with my ups and downs. So far this burning season I had 1 major spike going over 1700 degrees and my temperature probe went bad.. man was that annoying with the alarm going off. I.had a spare so I put that on and been good ever since and somehow I killed a steel cat..

As a side note I dont think that my stove has run this long without going cold more then once.. its a new Woodsplitter67 record. This stove overall has .what I think.. run well all heating season. I've been out back splitting.. well because thats wat a Woodsplitter67 does.

Seems very odd you would use up a cat that fast, maybe you got a weak one? Mine is still working after routinely hitting 1650 and a few 1750's.... 3 months of 24/7 burning, so far but it is showing signs of stress for sure.

Nice pile of wood there. Still trying to burn through my stockpile of 15 cord.....

Dragon fireplace.... very cool. I showed the wife, she looked at the pics, she said "cool!" She looked at me and said, "No!" thats it, end of conversation.

 

[dmccoole]

Seems very odd you would use up a cat that fast, maybe you got a weak one? Mine is still working after routinely hitting 1650 and a few 1750's.... 3 months of 24/7 burning, so far but it is showing signs of stress for sure.

Nice pile of wood there. Still trying to burn through my stockpile of 15 cord.....

Dragon fireplace.... very cool. I showed the wife, she looked at the pics, she said "cool!" She looked at me and said, "No!" thats it, end of conversation.

"a few 1750's" Does your pipe go red hot like mine did? I think mine only got to 1746 or maybe 1748.