2023/24 VC Temperature discussion thread

[arnermd]

I think there are some good nuggets of advice here, could you clarify a couple things for us:

So I stay away from doing it like. I dont like doing it tats was cor a couple reasons the most important is.. alot of smoke is getting into the stovepipe.

So what do you normally do? Do you reload with cat hotter than 350? Or do you wait and let it come down more?

If the catalyst is like 350 the stove is still pretty warm so it shouldn't take long to get it back up to temperature.. I normally will reestablish draft, SST and then re-engage the cat.

• How do you re-establish draft?
  • Do you throw a couple sticks in and let if warm up with cat bypassed? Or do you load it up and burn in bypass?
• How do you know when draft is reestablished?
  • Are you looking for a flue temp?
  • How are you measuring flue temp? Magnetic? How far above the stove top?
• SST? Not sure what that stand for...

Sometimes I do rake the.coals to the back to help things along. Once I get close to the draft I need, Ill move things around in the box, add wood and close the bypass to ensure it kicks off quickly.

• How do you know when you have the draft you need?
• When you move things around in the box what are you trying to do there?
  • I will try to keep fresh wood away from the bottom back corner, right at the secondary inlet. I suspect active flames there will get sucked up into the cat and stress the refractory. So I try to keep it out of that area.

 

[JohnDaileyNH]

I think there are some good nuggets of advice here, could you clarify a couple things for us:


So what do you normally do? Do you reload with cat hotter than 350? Or do you wait and let it come down more?

• How do you re-establish draft?
  • Do you throw a couple sticks in and let if warm up with cat bypassed? Or do you load it up and burn in bypass?
• How do you know when draft is reestablished?
  • Are you looking for a flue temp?
  • How are you measuring flue temp? Magnetic? How far above the stove top?
• SST? Not sure what that stand for...

• How do you know when you have the draft you need?
• When you move things around in the box what are you trying to do there?
  • I will try to keep fresh wood away from the bottom back corner, right at the secondary inlet. I suspect active flames there will get sucked up into the cat and stress the refractory. So I try to keep it out of that area.

I typically reload around 600-650 thats been my sweet spot to get my cat back up to temp and not go nuclear. I've noticed sub 500 it needs to to catch and get hotter before it will re-engage properly.

I stopped raking coals to the back and just stir and spread. Seems to be easier to control this way.

 

[AsylumResident]

I did not say I was doing a hot reload, you may have been thinking of the post by @AsylumResident. Hard to keep all the posts straight....

I avoid hot reloads, for the reason you stated.,... nuclear.

Plenty of good posts flying around. When I say hot reload I’m typically under 500 for a cat temp. To me a hot reload is being able to use the coals to get things going again. I’ve been doing so many cold starts with the way the weather has been.

 

[Woodsplitter67]

I got lucky this morning.. Im doing the ultra low burn today and this should carry me into this afternoon.. I was trying to make sure the stove didn't take off on me

 

[Woodsplitter67]

I did not say I was doing a hot reload, you may have been thinking of the post by @AsylumResident. Hard to keep all the posts straight....

I avoid hot reloads, for the reason you stated.,... nuclear.

I miss read the post.. reading tons of stuff.. my error..

 

[arnermd]

Plenty of good posts flying around. When I say hot reload I’m typically under 500 for a cat temp. To me a hot reload is being able to use the coals to get things going again. I’ve been doing so many cold starts with the way the weather has been.

Ah ok.... just to avoid confusion...

• For me a hot reload is when the cat is over 500, thick bed of coals you load it up and immediately engage the cat and it takes off to 1000 in less than ~ 10 minutes. The goal is to keep the cat rolling at >1000F and for my stove it is a higher likelihood of cat over fire, so I avoid it when I can.
• Using coals to light off the next load, with cat 200-400 is "normal / typical" for me
• "Cold" start is when I need to strike a match.

 

[AsylumResident]

Ah ok.... just to avoid confusion...

• For me a hot reload is when the cat is over 500, thick bed of coals you load it up and immediately engage the cat and it takes off to 1000 in less than ~ 10 minutes. The goal is to keep the cat rolling at >1000F and for my stove it is a higher likelihood of cat over fire, so I avoid it when I can.
• Using coals to light off the next load, with cat 200-400 is "normal / typical" for me
• "Cold" start is when I need to strike a match.

I have yet to establish a normal. Now that I'm able to track things imperically I am doing the same thing over and over to get a baseline I am comfortable with. Then I'll start doing specific variations to see if the effect is overall better or worse (one variable at a time). The only thing I haven't set up yet is to track draft. Been crazy with life in this household lately. Three young boys and dog just past the puppy stage.

 

[arnermd]

Burn from yesterday.

• Started burning my "good" wood, ash / red oak, 13-16% MC
• Had a heavy bed of coals, opened air to cook that down and heat the stove back up
• Added two smaller splits to bring stack temp up, waited 30 min for them to catch good (I do not normally do this)
• Added more wood, full load
• Engaged the cat, very quick light off.... Got distracted and forgot to bring the air down
• Remembered to bring air down and set to 50%, cat temps came back down, which was a pleasant surprise.
• Burn was going well, Took a couple draft readings as noted below
• at 11:50 I heard the stove was starting to surge, no smoke out the griddle gasket but I could hear it and see it on the flue temps. I have no idea why.... Burn was good for many hours and then it started.
• Reduce air very slightly to 40%, surging stopped.
• 5.5 hours of cat hot time seems very good to me, overall the burn was excellent except for the surging.....

VC has said back puffing is a result of reducing air to fast or insufficient draft. I did not touch the air and draft was healthy at 0.1+ iwc, so I don't get it.... Wondering if maybe my air flapper is not set right or thermostat is not working correctly???

Last I checked a few weeks ago, flapper was just closed with a cold stove and lever all the way back.

 

[AsylumResident]

For my burns this weekend I would open the bypass and air to let the coals burn down some when it was time to reload. I typically do a reload when the cat drops under 500. When I loaded it back up I have been playing with different flue gas temps on when is the best time to engage the cat. I found that engaging the cat when the flue is at 600, the cat doesn't peak as high. I waited until the flue was 700 a couple times and that resulted in the cat to peak somewhere north of 1,600 each time. If I engaged cat with flue temps below 600, the cat will barely reach 1000. Right now it seems that flue temps of 600-650 to engage the cat is the sweet spot.

 

[AsylumResident]

Burn from yesterday.

• Started burning my "good" wood, ash / red oak, 13-16% MC
• Had a heavy bed of coals, opened air to cook that down and heat the stove back up
• Added two smaller splits to bring stack temp up, waited 30 min for them to catch good (I do not normally do this)
• Added more wood, full load
• Engaged the cat, very quick light off.... Got distracted and forgot to bring the air down
• Remembered to bring air down and set to 50%, cat temps came back down, which was a pleasant surprise.
• Burn was going well, Took a couple draft readings as noted below
• at 11:50 I heard the stove was starting to surge, no smoke out the griddle gasket but I could hear it and see it on the flue temps. I have no idea why.... Burn was good for many hours and then it started.
• Reduce air very slightly to 40%, surging stopped.
• 5.5 hours of cat hot time seems very good to me, overall the burn was excellent except for the surging.....

VC has said back puffing is a result of reducing air to fast or insufficient draft. I did not touch the air and draft was healthy at 0.1+ iwc, so I don't get it.... Wondering if maybe my air flapper is not set right or thermostat is not working correctly???

Last I checked a few weeks ago, flapper was just closed with a cold stove and lever all the way back.

View attachment 318597

Nice long time over 1000! I haven't had back puffing yet.

This weekend I did a full load and went to close the bypass. The bypass wouldn't close. Slight bit of panic, I didn't realize I placed the top piece of wood in just the right spot to not let the bypass close.

 

[arnermd]

Nice long time over 1000! I haven't had back puffing yet.

This weekend I did a full load and went to close the bypass. The bypass wouldn't close. Slight bit of panic, I didn't realize I placed the top piece of wood in just the right spot to not let the bypass close.

hahahaha.... this happens to me all the time. Just this morning I was trying to shoehorn in big split at the top..... Had to close bypass with the griddle open while holding the split forward.

Another trick, sometimes it is easier to load the last few pieces from the front, open the doors. This is fine if you got a lean bed of coals, but if you have a nice hot bed of coals things get interesting..... Lots of flames...

I used to cut all my wood to 20" and I would split them them as big as I thought would fit to try and get longer burns. I have since learned that a mix of short, small / big is the best because I can mix and match when I load to make it all fit. Wood stove Tetris....

Interesting observation on the flue temps, @Woodsplitter67 has advocated this as well.... How are you measuring the flue temp? And where?

When we gonna see some draft readings? Inquiring minds want to know.

 

[AsylumResident]

hahahaha.... this happens to me all the time. Just this morning I was trying to shoehorn in big split at the top..... Had to close bypass with the griddle open while holding the split forward.

Another trick, sometimes it is easier to load the last few pieces from the front, open the doors. This is fine if you got a lean bed of coals, but if you have a nice hot bed of coals things get interesting..... Lots of flames...

I used to cut all my wood to 20" and I would split them them as big as I thought would fit to try and get longer burns. I have since learned that a mix of short, small / big is the best because I can mix and match when I load to make it all fit. Wood stove Tetris....

Interesting observation on the flue temps, @Woodsplitter67 has advocated this as well.... How are you measuring the flue temp? And where?

When we gonna see some draft readings? Inquiring minds want to know.

Tetris for sure.

I have a type k thermocouple inside the flue about 18" up from the stove top. My data tracker only takes two thermocouples so I have the STT and the cat on that with the Auber meter hanging on the wall for the flue temps. I got my data tracker through ThermoWorks. I originally bought the wrong one but they called me and spent quite a bit of time discussing what I wanted to use it for so they could best fit my needs. Great customer service. I told them the only issue I have now is that I need it to have more than two thermocouple connectors. We'll see if they decided to develop a new one or not.

On Sunday I got the magnehelic gauge set up and then I found out it wasn't working. I grabbed an older one from work that ended up taking a crap. I'm grabbing a newer one today but temps are going to be pretty warm this week so not too much burning. I would think by this weekend I should have it all set up and burning again to get some results.

 

[arnermd]

Tetris for sure.

I have a type k thermocouple inside the flue about 18" up from the stove top. My data tracker only takes two thermocouples so I have the STT and the cat on that with the Auber meter hanging on the wall for the flue temps. I got my data tracker through ThermoWorks. I originally bought the wrong one but they called me and spent quite a bit of time discussing what I wanted to use it for so they could best fit my needs. Great customer service. I told them the only issue I have now is that I need it to have more than two thermocouple connectors. We'll see if they decided to develop a new one or not.

On Sunday I got the magnehelic gauge set up and then I found out it wasn't working. I grabbed an older one from work that ended up taking a crap. I'm grabbing a newer one today but temps are going to be pretty warm this week so not too much burning. I would think by this weekend I should have it all set up and burning again to get some results.

What dia is your TC? I have an 1/8". You must get to 600-650 pretty quick if you are measuring exhaust gas temp.

With the cat bypassed I can get 600-650 gas temp in ~15 min from cold start, Not nearly enough time to get the griddle hot....

 

[AsylumResident]

What dia is your TC? I have an 1/8". You must get to 600-650 pretty quick if you are measuring exhaust gas temp.

With the cat bypassed I can get 600-650 gas temp in ~15 min from cold start, Not nearly enough time to get the griddle hot....

Mine is also 1/8". For a reload I get the flue to 600-650 and hit the bypass usually takes 20ish minutes to get there. My STT is usually in the mid 300's at this point and takes awhile to rebound with a full load of wood.

 

[arnermd]

Interesting.... my manual says to look for griddle temp > 450F to engage the cat. 350 seems a little on the cool side to me, but if that is working for you, go with it. I need to try it again myself, but in the past when I engage cat with griddle < 400 I end up with cat overfires a couple hours later, very smoky primary burn..... I seem to do better (less chance of cat overtemps) with a hotter primary burn before throwing in the cat.

You may also be benefitting from a brand new cat... very active. Very curious to see how your burns go as it ages....

 

[Woodsplitter67]

Interesting.... my manual says to look for griddle temp > 450F to engage the cat. 350 seems a little on the cool side to me, but if that is working for you, go with it. I need to try it again myself, but in the past when I engage cat with griddle < 400 I end up with cat overfires a couple hours later, very smoky primary burn..... I seem to do better (less chance of cat overtemps) with a hotter primary burn before throwing in the cat.

You may also be benefitting from a brand new cat... very active. Very curious to see how your burns go as it ages....

I fined that the manual can be a little off. I think it has more to do with each person's setup and what there putting in to it.

As far as flue temps.. Im using a magnetic bi mettle.. heres the weird thing.. its a double wall so the temperatures are not accurate and the readings aren't true because of the double wall.. After time I have figured out that I can engage the bypass between 250 and 300 and the catalyst will light off every time.. but what the actual flue gasses are I dont know..

 

[AsylumResident]

When we gonna see some draft readings? Inquiring minds want to knknow.

Today looked at how I would install this. The magnehlic gauge comes with a thin aluminum pipe about 3/16 in diameter and 5" long. That connects to a rubber hose that connects to the gauge.

Two things; should I find a different metal tube, maybe copper? I will have to drill into my stove pipe, which is double walled. How do I keep the metal pipe secured? Drill the hole to fit the pipe as tight as possible or is there some sort of a fitting I can use to put in the hole that would hold the metal tube and keep things relatively air tight?

 

[xanadu1797]

Couple of questions that I'm sure have been discussed many times:
what is the ideal temp range for VC Encore flexburn cat?
why does my cat run better with the factory air supply blocked off?
i'm seeing temps of 1000-1300 with it shut but if i run it like it's designed to be run my cat hovers at 600-800....

 

[Woodsplitter67]

Couple of questions that I'm sure have been discussed many times:
what is the ideal temp range for VC Encore flexburn cat?
why does my cat run better with the factory air supply blocked off?
i'm seeing temps of 1000-1300 with it shut but if i run it like it's designed to be run my cat hovers at 600-800....

so with the air off 1000 to 1450 are good temp.. with the air up say mid way 800 to 1200 is good.. To me .. really temperature doesn't make a big difference as long as there is no smoke coming out of the stovepipe.. and the cats not going nuclear..

Look at it like this.. if your catalyst is at 800 degrees and no smoke coming out of the chimney.. well that's a good burn.. good burns are burns that are clean and doesn't overheat the house or under heat the house..

 

[xanadu1797]

Yeah, makes sense to me.

 

[xanadu1797]

so with the air off 1000 to 1450 are good temp.. with the air up say mid way 800 to 1200 is good.. To me .. really temperature doesn't make a big difference as long as there is no smoke coming out of the stovepipe.. and the cats not going nuclear..

Look at it like this.. if your catalyst is at 800 degrees and no smoke coming out of the chimney.. well that's a good burn.. good burns are burns that are clean and doesn't overheat the house or under heat the house..

Oh, I'm talking about the air supply for the catalyst which on my stove is a port distinct from the air feed you control with a lever on the side of the stove. seems like when the cat air supply is blocked off (with a piece of tin secured by a magnet) the cat temps are signifigantly higher.
My cat went nuclear years ago and I refitted/rebuilt the stove- see profile pic. Maybe I didn't quite put it back together right...

 

[arnermd]

Today looked at how I would install this. The magnehlic gauge comes with a thin aluminum pipe about 3/16 in diameter and 5" long. That connects to a rubber hose that connects to the gauge.

Two things; should I find a different metal tube, maybe copper? I will have to drill into my stove pipe, which is double walled. How do I keep the metal pipe secured? Drill the hole to fit the pipe as tight as possible or is there some sort of a fitting I can use to put in the hole that would hold the metal tube and keep things relatively air tight?

Bunch of thoughts here.....

• 5" is not nearly enough length, the end of the tube is going to get hot and it will melt that gage.....
• You really want something that is not conductive and thin, aluminum / copper are very conductive, steel or stainless would be slightly better (less conductive).
• I use 1/8" soft copper tube but it is about 18" long and I do not leave it in the flue, I use the same hole as my TC. I remove my TC, insert my copper tube about centered in exhaust pipe, take a reading, remove the tube and reinstall my TC.
• If you leave the tube installed permanently it will get hot, unless you have enough length or add some fins.
  • An easy way to add some fins would be to create a stack of alternating regular/fender washers that fit snug on the OD of the tube.
  • Another idea: Use several feet of tube and coil it up so it can cool. Like the old steam fitters used to do.
• If you leave the tube installed permanently it is going to plug up, the tube will be cold relative to the exhaust gas so you will be collecting creosote there and eventually it will plug up.
  • My exhaust TC is a great burn indicator, I will pull it out and look at it, if it is grey and relatively clean I know my burn was clean, if it comes out black and crunchy I know I was not burning clean, if it comes out black and wet/sticky with lots of buildup I know it was a real bad burn (wet wood)
• Where to install: I assume you have an oval to round adapter coming out of the stove? I expect you have some screws at the top of the adapter to secure the round end to your stove pipe? Take one of those screws out and insert your tube there. This is what I do.
  • Air leaks: I do not worry about it, I have 3 holes in my stovepipe (2 for my key damper and 1 for the TC) air leaks into those holes all the time. A little air leak is not going to affect anything.
  • If you are worried about it you could slap some Aluminum tape on it or pack insulation over it, but honestly I think it will be fine as long as it is relative small....
  • I have an 1/8" TC and the hole for it is about 3/16" so there is not much air leaking past that.

My suggestion: Do not permanently install it, get an 1/8" tube and just insert / remove it through a screw hole to take a reading.

Pics below of my setup and how I do it.

 

[arnermd]

Oh, I'm talking about the air supply for the catalyst which on my stove is a port distinct from the air feed you control with a lever on the side of the stove. seems like when the cat air supply is blocked off (with a piece of tin secured by a magnet) the cat temps are signifigantly higher.
My cat went nuclear years ago and I refitted/rebuilt the stove- see profile pic. Maybe I didn't quite put it back together right...

Sounds like you have too much secondary air to me.... but as @Woodsplitter67 says, if you are burning clean that's the major concern.

It can be hard to tell if you are getting smoke or steam sometimes..... I found it is best viewed against a clear blue sky. If it is pure white and dissipates quickly it is steam, if it is gray and tends to hang around it is smoke. Very hard to tell sometimes.....

Are you burning small fires? If so the secondary air may be diluting the burn, try a bigger fire.

I have also seen this happen with wet wood, all the moisture quenches the secondary burn.

 

[Woodsplitter67]

Sounds like you have too much secondary air to me.... but as @Woodsplitter67 says, if you are burning clean that's the major concern.

It can be hard to tell if you are getting smoke or steam sometimes..... I found it is best viewed against a clear blue sky. If it is pure white and dissipates quickly it is steam, if it is gray and tends to hang around it is smoke. Very hard to tell sometimes.....

Are you burning small fires? If so the secondary air may be diluting the burn, try a bigger fire.

I have also seen this happen with wet wood, all the moisture quenches the secondary burn.

wet wood kills a secondary.. any.. catalyst burn tube..

 

[AsylumResident]

Here's my run from last night:
- Cold start
- Once I had a good bed of coals I loaded up about 3/4 full with ash
- Let that catch with air open 100% until flue temp reached 650
- When flue hit 650 I closed the bypass. Took about 20 minutes to reach 650.
- Kept air at 100% open until the cat reached 1000.
- When cat hit 1000 I dialed the air back to 50% and let it burn.



I've been able to replicate this burn pretty consistently. I would like to see a little longer burn time with a 3/4 load. I know I don't have the air closed down as far as I could but with this burn my STT peaked at 429 I'm not too interested in a much lower STT.