2021/22 VC Owner thread

[Diabel]

My procedure is very similar to @RandyBoBandy s. Except, i do not do a top down & I close the bypass once my cat temp reaches 750. The rest is pretty identical, including the 100% air closing then backing off a bit.

 

[RandyBoBandy]

My procedure is very similar to @RandyBoBandy s. Except, i do not do a top down & I close the bypass once my cat temp reaches 750. The rest is pretty identical, including the 100% air closing then backing off a bit.

You leave your damper open until the cat hits 750? How do you keep your flue from melting?

 

[Diabel]

You leave your damper open until the cat hits 750? How do you keep your flue from melting?

Flue will read 400 ~ when cat is at 750. Conventional cold start

 

[clancey]

Yea I know what you mean about the moisture meter for mine I have to drill into wood to place it and then see what the level is--what a pain...clancey

 

[RandyBoBandy]

Flue will read 400 ~ when cat is at 750. Conventional cold start

That’s crazy. My flue will hit 600 way before my cat hits 750. I’m often launching the cat at 200-300 degrees.

 

[Diabel]

That’s crazy. My flue will hit 600 way before my cat hits 750. I’m often launching the cat at 200-300 degrees.

That’s crazy. My flue will hit 600 way before my cat hits 750. I’m often launching the cat at 200-300 degrees.

Sorry Randy. I dont know what went through my head when I wrote this. I close the bypass when flue reaches 400 (flue temp moves fast at this point). At 400 flue the cat will read anywhere between 250-400. Once I close the bypass the cat will move fast. Within a minute or two it will be at 750 at which point I start closing the primary air in increments. Again sorry for confusing things.

 

[arnermd]

Well that data logger is pretty damn cool. One thing I noticed is you are chopping your primary air too much too fast (in my opinion).
A typical and very general schedule of my procedure:
Cold start.
-Large splits on bottom row, then medium, small, kindling and tinder on top. Light fire top down. Primary air fully open.
-Flue probe reads 600*=>close damper
-Cat reads 800*-1000* =>close primary 25%.
-Cat reads 1200*-1300* =>close primary 25%
-Cat reads 1400*-1450* =>close primary 25%
-Cat reads 1525*-1549* => find fully closed and open primary 5%.
I find fully closed by lightly moving the air lever back and forth until I hear the flapper hitting the frame. Then I just open the air slightly. This will put the brakes on the cat on it generally settles in to something between 1100-1400. Now there are many factors that take me off my routine, however this is a general and effective method for my set up.
I’ve been playing around with leaving the primary fully open until GT reads 500-550. It’s an interesting race at times between the cat and the GT. If the cat is reaching my no go zone before I can my GT to 500 I am forced to shut the primary down in 33% increments.
Following these methods keeps my stove out of 1550* and above.

Thanks Randy, I am going to try your method and see how it works for my stove.

Data logger is working very well....

I resealed by secondary inlet yesterday with some magnetic strips on the outside. Big change in how the stove is reacting. I think the thermal event in the data above may have been because my secondary plug was leaking..... I have some neodymium magnet bars on order for a more permanent solution, will post pictures when I get it worked out.

Data from yesterday afternoon and last night below. Looks really good to me, a bit erratic because I was messing with things. I even tried the dreaded hot reload (throw in more wood when the secondary is still hot, wait a few minutes and close the bypass). In the past when I did these there was a very high probability the secondary would go nuclear. Not so this time! Secondary got hot for a short blip but came right back down. Temp bumped up to 1050F ~2 hours later as it worked through the fresh load, but settled back in for the night.

I am feeling pretty good about the changes, we shall see if it lasts, I am cautiously optimistic. Might be time to get a new cat on order.....

 

[Rusty18]

May have been mentioned above and I missed it but mine behaves much much better with a full ash pan and about 1” of ash piled above the grate.

 

[RandyBoBandy]

Thanks Randy, I am going to try your method and see how it works for my stove.

Data logger is working very well....

I resealed by secondary inlet yesterday with some magnetic strips on the outside. Big change in how the stove is reacting. I think the thermal event in the data above may have been because my secondary plug was leaking..... I have some neodymium magnet bars on order for a more permanent solution, will post pictures when I get it worked out.

Data from yesterday afternoon and last night below. Looks really good to me, a bit erratic because I was messing with things. I even tried the dreaded hot reload (throw in more wood when the secondary is still hot, wait a few minutes and close the bypass). In the past when I did these there was a very high probability the secondary would go nuclear. Not so this time! Secondary got hot for a short blip but came right back down. Temp bumped up to 1050F ~2 hours later as it worked through the fresh load, but settled back in for the night.

I am feeling pretty good about the changes, we shall see if it lasts, I am cautiously optimistic. Might be time to get a new cat on order.....

View attachment 290585

Making progress. Only thing I see in your second graph is you shut your damper too early. This is probably why you had to open your air back up

 

[RandyBoBandy]

May have been mentioned above and I missed it but mine behaves much much better with a full ash pan and about 1” of ash piled above the grate.

This is a good point. I also usually have about 2” of ash in my stove. Coals last much longer. I keep going back and forth from using the ash pan and just shoveling out ash. It seems to be cleaner shoveling out ash. Every time I open the ash pan door it goes everywhere.

 

[RandyBoBandy]

Sorry Randy. I dont know what went through my head when I wrote this. I close the bypass when flue reaches 400 (flue temp moves fast at this point). At 400 flue the cat will read anywhere between 250-400. Once I close the bypass the cat will move fast. Within a minute or two it will be at 750 at which point I start closing the primary air in increments. Again sorry for confusing things.

Ok that sounds better. I was scratching my head trying to figure out how that was even possible.

 

[gthomas785]

Glad to know I'm not insane also. Every now and then I see a post about waiting until the cat is >500 before closing the bypass which baffles me because I don't think my cat would ever get to 500 with the bypass open.

 

[arnermd]

This is a good point. I also usually have about 2” of ash in my stove. Coals last much longer. I keep going back and forth from using the ash pan and just shoveling out ash. It seems to be cleaner shoveling out ash. Every time I open the ash pan door it goes everywhere.

I think you are right as usual, I did throw the damper too early and I had to goose the air to get the temps up.... will wait for higher temps going forward. Flue was just hitting 700 (gas temp) will wait for 750 and try that. Might have to wait a bit longer with no cat as the cat will help light off at lower temps....

Ash: I empty my ash pan every 3-4 days before it gets full.... it makes a smaller mess if it is not full. Generally I have little ash on the grate, some in the corners. I do get a layer of coals that sit there above the grate. My coal bed is a lot deeper since I plugged the secondary. I am thinking my temps are generally too low now. May open up a little secondary air once I get this setup learned out and consistent.

Another thought I have been kicking around: By blocking off the secondary air flow we are eliminating the air flowing through the interior of the refractory, this air helps cool the refractory. Maybe it is not significant, but by eliminating this air flow the refractory will run hotter. Of course it is all relative, I am pretty sure no airflow through there at 1000-1400 gas temp is better than some flow with 1800F runaway cat temps..... I know for a fact the refractory does not like 1800 for long. My first two lasted ~4 years each and looked pretty stressed (flaky / spalling surface) when they came out.

 

[RandyBoBandy]

I think you are right as usual, I did throw the damper too early and I had to goose the air to get the temps up.... will wait for higher temps going forward. Flue was just hitting 700 (gas temp) will wait for 750 and try that. Might have to wait a bit longer with no cat as the cat will help light off at lower temps....

Ash: I empty my ash pan every 3-4 days before it gets full.... it makes a smaller mess if it is not full. Generally I have little ash on the grate, some in the corners. I do get a layer of coals that sit there above the grate. My coal bed is a lot deeper since I plugged the secondary. I am thinking my temps are generally too low now. May open up a little secondary air once I get this setup learned out and consistent.

Another thought I have been kicking around: By blocking off the secondary air flow we are eliminating the air flowing through the interior of the refractory, this air helps cool the refractory. Maybe it is not significant, but by eliminating this air flow the refractory will run hotter. Of course it is all relative, I am pretty sure no airflow through there at 1000-1400 gas temp is better than some flow with 1800F runaway cat temps..... I know for a fact the refractory does not like 1800 for long. My first two lasted ~4 years each and looked pretty stressed (flaky / spalling surface) when they came out.

May I suggest letting some ash build up in the box. Let a couple inches build up. I know the older stoves have epa holes just behind the front legs that let air into the ash pan cavity. Letting ash build up in the box essentially blocks this air.

 

[arnermd]

May I suggest letting some ash build up in the box. Let a couple inches build up. I know the older stoves have epa holes just behind the front legs that let air into the ash pan cavity. Letting ash build up in the box essentially blocks this air.

My stove has an EPA hole too.... It is under the ashpan at the back in the center, near where the primary air comes in. I have experimented with plugging it, did not seem to make much difference. I may try again with this new configuration.

Data plots from yesterday.
- For the evening load I tried to follow Randy's procedure, could not really get the temps up, closing air down to 50% seems to stall out the secondary. I feel like it needs more air. No doubt my stove reacts a little differently with no cat.
- Had some backpuffing 2 hours into the burn, further evidence the air was too low.

This morning the stove was acting wonky again, flue temps rocketing up to 1200, very aggressive. Checked on my secondary plug and it fell out, cheap magnets I used got cooked..... Re-sealed with some foil and all is good now. Always nice to find an obvious cause.

Where do you have your flue probe installed? How far up from the stove top? I assume you are near the center of the pipe? I noticed a fair bit of creosote coating mine this morning. I may open up the damper and burn it off....

 

[arnermd]

Well.... Nothing but good news to report, I think my stove and I have reconciled our differences. My heartfelt thanks to all who provided comments, but especially Randy.

I think the key fix was to seal the secondary air inlet at the inlet side (as suggested by several fine folks here). I mistakenly thought sealing the ports inside the stove had the same effect, while it helps, it is only a partial fix. I believe air is leaking at the secondary inlet port where the refractory mates with the cast iron base. Blocking the secondary inlet port outside the stove solves this.

• I sealed the secondary inlet with some neodymium bar magnets an aluminum foil. I favored this approach because it is easily adjustable if I do need to let a little air in some time in the future. I am concerned that the heat may de-mag the magnets over time, I am thinking some AL flashing with thin ceramic insulation as a gasket / thermal break might solve that problem.
• I reinstalled one of my old cats I had laying around. It had some holes in it (~20%) where the grid had crumbled. I took some larger pieces from my latest crumbled cat and simply set them on top of the holes in the old one. We shall see how long that lasts.
• I am amazed at how fast the cat lights off and heats up. My stove never acted this way before. I find I am closing the air down 5-10 minutes after I close the damper. Used to take 30-40 minutes.
• The peak cat temps are stable and controllable, if I close down the air the secondary temp responds. This has never happened before.
• I am burning through some smaller short pieces right now so the cat temps drop off in a few hours, I suspect if I had some bigger solid full length splits it would go longer. My burn times do not seem to be any longer than usual, but that may be because of the wood.
• Data from yesterday is plotted below. Any fine tuning tips would be appreciated. I have been dropping the flue gas temp at which I engage the cat. This morning it went off fine at 700F.

Best regards to all the fine folks in this forum.

 

[gthomas785]

Are you getting any chimney smoke with the secondary fully blocked? When I tried that my stove would continue to give light wisps of grey smoke throughout the burn so I had to make holes to let in a bit of secondary air.

 

[arnermd]

I took a series of pictures this afternoon for todays burn. Very clear cold day here in CT..... Occasional breeze but pretty still.
I specify the time since reload and the relevant temps for each shot. This load took a bit longer to crank up the cat, had some bigger splits in there, may have been higher moisture content.

There is some creosote buildup on my cap and screen, I have been running cold for much of the season trying to prevent the secondary from going nuclear. And I have run without a cat installed for a while.....

10 min, Damper open, Flue gas @ 600F, clearly grey smoke

19 minutes, Damper closed, 800F secondary, some smoke

25 min, 1000F secondary, still some smoke

60 min, 1125F secondary, still some grey

83 min, 1200F, almost all gone

120 min, 1310F, all gone.... nothing, little bit of steam once in a while

140 min, 1200F, cruising, no plume If the breeze is right I do get a very slight smell of smoke, so pretty sure it is not all burned

 

[arnermd]

That last picture (bottom right) is not correct, I got them mixed up..... Unfortunately I can't figure out how to edit the previous post.....

 

[gthomas785]

Looks like your cat is running a little rich, mine will hit 1300 much earlier with no smoke at that point (maybe 1 hour in)

 

[RandyBoBandy]

My stove has an EPA hole too.... It is under the ashpan at the back in the center, near where the primary air comes in. I have experimented with plugging it, did not seem to make much difference. I may try again with this new configuration.

Data plots from yesterday.
- For the evening load I tried to follow Randy's procedure, could not really get the temps up, closing air down to 50% seems to stall out the secondary. I feel like it needs more air. No doubt my stove reacts a little differently with no cat.
- Had some backpuffing 2 hours into the burn, further evidence the air was too low.

View attachment 290631

This morning the stove was acting wonky again, flue temps rocketing up to 1200, very aggressive. Checked on my secondary plug and it fell out, cheap magnets I used got cooked..... Re-sealed with some foil and all is good now. Always nice to find an obvious cause.

Where do you have your flue probe installed? How far up from the stove top? I assume you are near the center of the pipe? I noticed a fair bit of creosote coating mine this morning. I may open up the damper and burn it off....

Sorry for the late response. My pipe probe is 18” up from the top of stove.

 

[RandyBoBandy]

Well.... Nothing but good news to report, I think my stove and I have reconciled our differences. My heartfelt thanks to all who provided comments, but especially Randy.

I think the key fix was to seal the secondary air inlet at the inlet side (as suggested by several fine folks here). I mistakenly thought sealing the ports inside the stove had the same effect, while it helps, it is only a partial fix. I believe air is leaking at the secondary inlet port where the refractory mates with the cast iron base. Blocking the secondary inlet port outside the stove solves this.

• I sealed the secondary inlet with some neodymium bar magnets an aluminum foil. I favored this approach because it is easily adjustable if I do need to let a little air in some time in the future. I am concerned that the heat may de-mag the magnets over time, I am thinking some AL flashing with thin ceramic insulation as a gasket / thermal break might solve that problem.
• I reinstalled one of my old cats I had laying around. It had some holes in it (~20%) where the grid had crumbled. I took some larger pieces from my latest crumbled cat and simply set them on top of the holes in the old one. We shall see how long that lasts.
• I am amazed at how fast the cat lights off and heats up. My stove never acted this way before. I find I am closing the air down 5-10 minutes after I close the damper. Used to take 30-40 minutes.
• The peak cat temps are stable and controllable, if I close down the air the secondary temp responds. This has never happened before.
• I am burning through some smaller short pieces right now so the cat temps drop off in a few hours, I suspect if I had some bigger solid full length splits it would go longer. My burn times do not seem to be any longer than usual, but that may be because of the wood.
• Data from yesterday is plotted below. Any fine tuning tips would be appreciated. I have been dropping the flue gas temp at which I engage the cat. This morning it went off fine at 700F.

Best regards to all the fine folks in this forum.

View attachment 290819
View attachment 290818

This looks good. Sounds like you are gaining ground in this battle. My cap was looking good until I hit a bit of “not so great” wood in my shed. I had a few days of fighting with the stove to keep the cat temps in check while trying to also keep stove temps up.

 

[arnermd]

Looks like your cat is running a little rich, mine will hit 1300 much earlier with no smoke at that point (maybe 1 hour in)

Yeah I agree.... this burn was a little odd.... slow to heat up. I may have closed the air down too quickly.... Still learning how to control this stove in the new config.

 

[Woodsplitter67]

secondary burns in the box

 

[Woodsplitter67]

its really neat to watch when this happens.. I can say since the beginning of January we have been ripping through wood.. I can see myself burning just about 4 cords this year. unless we get a big warm up