2023/24 VC Temperature discussion thread

[Hbob]

My probe sits below the catalyst and it measures exit gasses. I found a diagram I attached that shows the VC airflow. This is why the probe digital or bipedal, will have a low or innactive reading before the damper is closed. There is very minimal air flow down there until the closed damper forces the air down through the cat then back out the back of the stove. When you think about it, it's a complex and probably over-engineered design in my opinion. But it works if the setup is right.

View attachment 325768

Thank you so much for this......that is what I thought I found when I investigated inside. Do folks using the thermocouple digital thermometer use the same factory location? It is interesting that the the heat goes down through the catalyst as it is contrary to the typical heat rises scenario. But good draft must counter the rise.

 

[JohnDaileyNH]

Thank you so much for this......that is what I thought I found when I investigated inside. Do folks using the thermocouple digital thermometer use the same factory location? It is interesting that the the heat goes down through the catalyst as it is contrary to the typical heat rises scenario. But good draft must counter the rise.

Yup same location. I use an Auber digital probe

 

[arnermd]

I am posting on this thread something I started on another but not hearing back from the VC Encore gurus. Is the factory probe location (the predrilled hole in the back of the stove) and sits below the catalyst on the down stream side of the catalyst? What is the actual path of air/gases starting in the main fire box and ending in the chimney? My guess is up out of the back of the firebox into the opening of the refractory wall and then down through the catalyst, past the probe, and then back up to the flue. The air holes in the bottom of the refractory wall, appear to be air to the main fire box only....no opening into the refractory or catalyst area. Am I seeing this right?
Before I got the stove, I assumed the air went up through the catalyst.

Agree with all in the post above by @JohnDaileyNH

I put these together last year to explain flow paths.

Schematic
Defiant Air Flow Paths

 

[skb31]

I have a similar pattern to each reload of wood so that’s good to see. Hot reloads are superior for consistent, more even temp burning. Had to start from cold today as it’s been warm and really noticed how much longer it takes to settle into a good pattern.

Stove top runs colder early in a reload and the cat hotter. Cutting air back to less than 25% before 1k on the cat probe and all the way shut at 1k or so. Cat chamber will rise to 1300+ and hang there for a good stretch while the griddle stays cooler. (~400). This takes 90 minutes to 2 hours. I’d say this is low to moderate heat.

Then the griddle temp will rise towards 500 as the cat temp settles between 1100 and 1300. Running what I would call 2/3 full (3-4 good size splits) I can get 4-6 hours of really nice moderate to high heat with peak STT readings of 550. I work the air open as it burns down. 6-8 hours between reloads works for me.

A metal cat came stock with this encore 2040 cat-c. I’ve seen the discussions about ceramic versus metal so I figured it’s worth a mention.

 

[Woodsplitter67]

The days I have been running the stove, its ran good with the ceramic cat installed. I took out the metal a few weeks ago with warmer weather coming. Ran a a steady 1383 last night

 

[arnermd]

Another crap show this morning..... Thought the restricted secondary inlet was working, guess not....

• Let the stove go out last night, had a few coals left this morning to light off a small load to heat things back up
• Had nice bed of hot coals when I loaded 4 med size splits, all Ash. About a 1/2 load.
• Cat was hot so engaged the damper right away and left air at 20% open.
• Cat went to 1400 and I though all was good.... Nope.
• At 1700 on the cat and 1350 stack temp I closed down the air and stack damper, but it was ineffective.
• Opened up the bypass damper to let it burn off some.
• When stack temps came back to earth I re-engaged the cat and all was fine after that.
• Googled Blaze King Ashford 30.0 and looked up IRS energy tax credit info.

I don't get it....

 

[AsylumResident]

Another crap show this morning..... Thought the restricted secondary inlet was working, guess not....

• Let the stove go out last night, had a few coals left this morning to light off a small load to heat things back up
• Had nice bed of hot coals when I loaded 4 med size splits, all Ash. About a 1/2 load.
• Cat was hot so engaged the damper right away and left air at 20% open.
• Cat went to 1400 and I though all was good.... Nope.
• At 1700 on the cat and 1350 stack temp I closed down the air and stack damper, but it was ineffective.
• Opened up the bypass damper to let it burn off some.
• When stack temps came back to earth I re-engaged the cat and all was fine after that.
• Googled Blaze King Ashford 30.0 and looked up IRS energy tax credit info.

I don't get it....

View attachment 326080

But hot damn, she's a good lookin' stove! Right?! This is such a perfect example of, "Looks aren't everything."

 

[JohnDaileyNH]

I am convinced this is more of a Defiant thing than Encore. My stove has been cruising, cat has stayed below 1450 running a week straight.

I know we've discussed this before, but the Defiant and Encore both use the same exact catalyst right? I believe this to be the biggest design flaw. You could argue the catalyst is undersized in the Encore. If it is the same with more fuel in the Defiant, this is always going to be an issue

 

[AsylumResident]

I am convinced this is more of a Defiant thing than Encore. My stove has been cruising, cat has stayed below 1450 running a week straight.

I know we've discussed this before, but the Defiant and Encore both use the same exact catalyst right? I believe this to be the biggest design flaw. You could argue the catalyst is undersized in the Encore. If it is the same with more fuel in the Defiant, this is always going to be an issue

I don't have an in depth knowledge of how the catalysts work and how that relates to surface area. But I do know that the Blaze King has a massive cat compared to the Defiant.

 

[arnermd]

I am convinced this is more of a Defiant thing than Encore. My stove has been cruising, cat has stayed below 1450 running a week straight.

I know we've discussed this before, but the Defiant and Encore both use the same exact catalyst right? I believe this to be the biggest design flaw. You could argue the catalyst is undersized in the Encore. If it is the same with more fuel in the Defiant, this is always going to be an issue

I believe they both use the same catalyst and the refractory engine is all identical.

Interesting that blaze king has a bigger cat.....

 

[gthomas785]

I am convinced this is more of a Defiant thing than Encore. My stove has been cruising, cat has stayed below 1450 running a week straight.

I know we've discussed this before, but the Defiant and Encore both use the same exact catalyst right? I believe this to be the biggest design flaw. You could argue the catalyst is undersized in the Encore. If it is the same with more fuel in the Defiant, this is always going to be an issue

I would believe that. I have an Intrepid which is a small stove but it has an even smaller catalyst. Temps are always out of control. My Encore is mostly well behaved, and it has a 2x larger catalyst for what is basically a ~1.5x larger stove. I would think the larger cat spreads the heat over a larger area so it makes sense the temp would be lower. The Defiant could certainly use a larger cat. If you go bigger, cost becomes a challenge as well as how to keep cat temps from stalling at the super low end of output.

 

[arnermd]

My latest experiement.....

Couple bar magnets restricting the primary air inlet. I have a sneaky suspicion my flapper is not shutting off and this results in the runaway condition.

This past week I ran with the magents more towards the center than in the pic below (more restrictive). I found:

• Loads were all ash, 3-4 large solid splits.
• No overtemp events, I was able to take the cat up to 1450 wide open and it dropped when I closed the air down
• Running less than 50% will completely choke out the fire even with a hot bed of coals and cat at 1300, if I drop air to <50% I wake up to charred wood in the box and cat at 300.
  • Makes sense as the air was severely restricted.....
  • This proves to me I have no significant leaks else where
• When lighting off cold I had some significant backpuffing even with the air wide open.
  • Makes sense as the stack was cold (low draft) and air was severely restricted.
• With the stove hot and air > 50% it seemed to run well on reloads, very controllable. Cat settled in around 900 - 1200.
• EPA hole was not plugged

I opened up the restriction a bit this morning, we shall see if I can dial it in and find the sweet spot.

 

[AsylumResident]

My latest experiement.....

Couple bar magnets restricting the primary air inlet. I have a sneaky suspicion my flapper is not shutting off and this results in the runaway condition.

This past week I ran with the magents more towards the center than in the pic below (more restrictive). I found:

• Loads were all ash, 3-4 large solid splits.
• No overtemp events, I was able to take the cat up to 1450 wide open and it dropped when I closed the air down
• Running less than 50% will completely choke out the fire even with a hot bed of coals and cat at 1300, if I drop air to <50% I wake up to charred wood in the box and cat at 300.
  • Makes sense as the air was severely restricted.....
  • This proves to me I have no significant leaks else where
• When lighting off cold I had some significant backpuffing even with the air wide open.
  • Makes sense as the stack was cold (low draft) and air was severely restricted.
• With the stove hot and air > 50% it seemed to run well on reloads, very controllable. Cat settled in around 900 - 1200.
• EPA hole was not plugged

I opened up the restriction a bit this morning, we shall see if I can dial it in and find the sweet spot.


View attachment 326310

How do the magnets restrict the air flow? Do they hold the flapper tight? Isn't there an air gap between the back of the magnet and front kmof the flapper?

 

[arnermd]

How do the magnets restrict the air flow? Do they hold the flapper tight? Isn't there an air gap between the back of the magnet and front kmof the flapper?

Yes there is a gap but it forces the air to make a turn. The magnets do not seem to hold the flapper closed, I was worried about that.

Unfortunately it reduces air flow at all flapper positions, which is not what I really want. But it was quick and easy.... This will be temporary until I can get in there and really see what is going on with the flapper.

 

[Woodsplitter67]

I make sure when I turn mine back I hers the flapper click against the body of the stove

 

[arnermd]

I make sure when I turn mine back I hers the flapper click against the body of the stove

Yeah others have told me that..... On mine I only hear it if I slam it back quickly, and I noticed sometimes I can pull on the cable and I will feel it seat, just a little. Hence my suspicion it is not closing all the way.

I know last time I rebuilt the stove I played with it to make sure it was seating and it seemed OK. Maybe not.

Once the burning season is over I am going to see if I can take that flapper assembly out without tearing down the stove. I think it will come out the hole but I may have to finagle the arm out.... We shall see.

 

[AsylumResident]

Last night we had a bad storm role through. Very heavy snow, very heavy winds. Thinking the power might go out I got a fire going. I burned a couple small and a couple medium splits down to a nice bed of coals then loaded it up with some bigger splits that barely fit lengthwise. I would say about 3/4 full of all ash. Once the cat hit 1000 I put the primary air to about 40% closed and walked away. A little over an hour later I hit 1400 on the cat. Not that big of a deal, but I haven't seen anything above 1300 in over a month. From there it hovered between 1450 and 1550. Not that big of deal.

What I am interested in is the flue temp (I measure internally). I had my alarm for the flue set at 750. At about 1:00am my alarm went off and my flue went from a little less than 750 to 950 in a matter of a few minutes. The cat bumped up a little and the STT temp didn't really change. I was able to increase the primary air some which created a consistent drop in the cat and the flue. Why would my flue temps all of sudden spike? Typically I will see a big spike in the cat in correlation with the flue. Not this time. Any idea what causes this event?

By the way, we didn't lose power but municipalities all around us did. Downed power lines and power poles snapped off.

 

[arnermd]

Last night we had a bad storm role through. Very heavy snow, very heavy winds. Thinking the power might go out I got a fire going. I burned a couple small and a couple medium splits down to a nice bed of coals then loaded it up with some bigger splits that barely fit lengthwise. I would say about 3/4 full of all ash. Once the cat hit 1000 I put the primary air to about 40% closed and walked away. A little over an hour later I hit 1400 on the cat. Not that big of a deal, but I haven't seen anything above 1300 in over a month. From there it hovered between 1450 and 1550. Not that big of deal.

What I am interested in is the flue temp (I measure internally). I had my alarm for the flue set at 750. At about 1:00am my alarm went off and my flue went from a little less than 750 to 950 in a matter of a few minutes. The cat bumped up a little and the STT temp didn't really change. I was able to increase the primary air some which created a consistent drop in the cat and the flue. Why would my flue temps all of sudden spike? Typically I will see a big spike in the cat in correlation with the flue. Not this time. Any idea what causes this event?

By the way, we didn't lose power but municipalities all around us did. Downed power lines and power poles snapped off.

View attachment 326429

Hmmm that is interesting.... I have seen flue spikes like that too but as you said I think it is always accompanied by a spike in cat temp.

Wondering if maybe you have an air leak in between the cat probe and the stack probe... like maybe at the oval to round adapter? My thinking is if you have a fresh source of oxygen and excess smoke downstream of the cat maybe you are getting combustion in the stack?

I usually use stove cement where the oval insets into the cast iron adapter, late in the season it cracks and chips due to the thermal cycles and is probably leaking some air into the stack.

Also interesting that it occurred right after the cat was falling off from the peak..... Maybe the flapper thermostat was just starting to open? Not sure why that would cause another spike in stack gas temp and not cat temps though.....

Another VC mystery.....

 

[AsylumResident]

Hmmm that is interesting.... I have seen flue spikes like that too but as you said I think it is always accompanied by a spike in cat temp.

Wondering if maybe you have an air leak in between the cat probe and the stack probe... like maybe at the oval to round adapter? My thinking is if you have a fresh source of oxygen and excess smoke downstream of the cat maybe you are getting combustion in the stack?

I usually use stove cement where the oval insets into the cast iron adapter, late in the season it cracks and chips due to the thermal cycles and is probably leaking some air into the stack.

Also interesting that it occurred right after the cat was falling off from the peak..... Maybe the flapper thermostat was just starting to open? Not sure why that would cause another spike in stack gas temp and not cat temps though.....

Another VC mystery.....

A leak is possible. I had to pack in a thicker rope gasket around the oval adapter because of a decent size gap at the connection. Maybe that has shifted or something. When I'm done burning for the year I'll take it apart and see.

 

[gthomas785]

Last night we had a bad storm role through. Very heavy snow, very heavy winds. Thinking the power might go out I got a fire going. I burned a couple small and a couple medium splits down to a nice bed of coals then loaded it up with some bigger splits that barely fit lengthwise. I would say about 3/4 full of all ash. Once the cat hit 1000 I put the primary air to about 40% closed and walked away. A little over an hour later I hit 1400 on the cat. Not that big of a deal, but I haven't seen anything above 1300 in over a month. From there it hovered between 1450 and 1550. Not that big of deal.

What I am interested in is the flue temp (I measure internally). I had my alarm for the flue set at 750. At about 1:00am my alarm went off and my flue went from a little less than 750 to 950 in a matter of a few minutes. The cat bumped up a little and the STT temp didn't really change. I was able to increase the primary air some which created a consistent drop in the cat and the flue. Why would my flue temps all of sudden spike? Typically I will see a big spike in the cat in correlation with the flue. Not this time. Any idea what causes this event?

By the way, we didn't lose power but municipalities all around us did. Downed power lines and power poles snapped off.

View attachment 326429

Maybe a little bit of crud burning off in the pipe? Just a thought

 

[Eman85]

Might have done a chimney cleaning on it's own.

 

[JohnDaileyNH]

Last night we had a bad storm role through. Very heavy snow, very heavy winds. Thinking the power might go out I got a fire going. I burned a couple small and a couple medium splits down to a nice bed of coals then loaded it up with some bigger splits that barely fit lengthwise. I would say about 3/4 full of all ash. Once the cat hit 1000 I put the primary air to about 40% closed and walked away. A little over an hour later I hit 1400 on the cat. Not that big of a deal, but I haven't seen anything above 1300 in over a month. From there it hovered between 1450 and 1550. Not that big of deal.

What I am interested in is the flue temp (I measure internally). I had my alarm for the flue set at 750. At about 1:00am my alarm went off and my flue went from a little less than 750 to 950 in a matter of a few minutes. The cat bumped up a little and the STT temp didn't really change. I was able to increase the primary air some which created a consistent drop in the cat and the flue. Why would my flue temps all of sudden spike? Typically I will see a big spike in the cat in correlation with the flue. Not this time. Any idea what causes this event?

By the way, we didn't lose power but municipalities all around us did. Downed power lines and power poles snapped off.

View attachment 326429

Storm rolled through here and been without power all day. Stove has kept the house at 70 the entire team. 2nd time this thing has saved my ass during an extended power outage

 

[Woodsplitter67]

I Think I have finally learned how to run my stove

 

[Woodsplitter67]

Storm rolled through here and been without power all day. Stove has kept the house at 70 the entire team. 2nd time this thing has saved my ass during an extended power outage

Self-reliance goes a long way.. I didn't realize how much I was a slave to the system.. Until I started providing more for myself

 

[Eman85]

I Think I have finally learned how to run my stove

I thought the same thing the other night, and it showed me what I know. Same batch of wood as previous burns that had me feeling good. Reloaded over a good hot coal base that burned down after cat reaching peak temps and dropping to just below 900. Left the air wide open after reload and engaged the cat with the box roaring. Watched the cat temps slowly drop into the 600's where in the past it would rise and I could shut the air back and not have to do any adjustments. It did rebound and give me a good overnight burn but it's a good thing I reload a couple of hours before bedtime to allow for any problems.