2024/25 VC performance discussion thread

[Turbo89]

You guys like living on the edge, I had 1 event about 1700-1750, and I went crazy troubleshooting.

Are you guys burning soaked wood or bad gaskets? Maybe try plugging a few secondary holes?

 

[56knoise]

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.

Thank you. I know it could be better, there are some bugs that I need to work out related to the remote monitoring and loss of internet connection but it has been extremely reliable so far. I'm sure I could get better control too with a better approximation of airflow and a better tune on the controller. I've managed to get the pid to hold tighter temperatures but the movements of the servo become aggressive and loud, the dog hates it and will run and hide in the other end of the house under a desk. The current values of kp 0.2, ki 0.1 and kd 0 keep it moving slowly and gradually and silent. I could replace the servo with something else like a stepper and an encoder but I've got too many other projects at the moment.

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.

That is the same conclusion I have reached. Any time the flame goes completely out and it smolders the cat wants to climb as high as it can and the stove cools down significantly. Good for overnight burns if you can control it but playing with the air and ensuring there is active flame in the firebox is much better for actual heating and keeping the cat under control.

Does your stove have the EPA holes near the front legs? They are 1/4 diameter and on both sides going into the ashpan area, always letting some air into the system which might explain your closed primary air and rising temps. I've plugged one of the holes on mine and it helped, I keep another plug ready for the other side just in case it decides to runaway due to an air leak or something.

 

[arnermd]

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

My exhaust pipe has never glowed.... Thats usually not my problem. I have seen exhaust temps in the 1200 region but they are pretty short, maybe 10 min max. My exhaust alarm is set to 850 and it rarely goes off. If I have a runaway cat and open the damper the stack temp will launch very quickly to 1000 - 1200 but that's expected.

 

[arnermd]

You guys like living on the edge, I had 1 event about 1700-1750, and I went crazy troubleshooting.

Are you guys burning soaked wood or bad gaskets? Maybe try plugging a few secondary holes?

I don't think anybody "likes" living on this edge... been troubleshooting for 12 years..... Plugged secondary's and it helps calm things down but not 100% effective.

 

[arnermd]

Thank you. I know it could be better, there are some bugs that I need to work out related to the remote monitoring and loss of internet connection but it has been extremely reliable so far. I'm sure I could get better control too with a better approximation of airflow and a better tune on the controller. I've managed to get the pid to hold tighter temperatures but the movements of the servo become aggressive and loud, the dog hates it and will run and hide in the other end of the house under a desk. The current values of kp 0.2, ki 0.1 and kd 0 keep it moving slowly and gradually and silent. I could replace the servo with something else like a stepper and an encoder but I've got too many other projects at the moment.

That is the same conclusion I have reached. Any time the flame goes completely out and it smolders the cat wants to climb as high as it can and the stove cools down significantly. Good for overnight burns if you can control it but playing with the air and ensuring there is active flame in the firebox is much better for actual heating and keeping the cat under control.

Does your stove have the EPA holes near the front legs? They are 1/4 diameter and on both sides going into the ashpan area, always letting some air into the system which might explain your closed primary air and rising temps. I've plugged one of the holes on mine and it helped, I keep another plug ready for the other side just in case it decides to runaway due to an air leak or something.

Control loop tuning is always balancing act.... Looks like you got a good system there.

EPA Holes: My stove has one in the bottom just in front of the primary flapper. I think its about 3/8" dia. I have plugged it with no real noticeable effect. Just to be clear, my over-temps are never on the primary side, Griddle is always 350 - 650.

 

[GrumpyDad]

Still havent finished the floors thus haven't installed the baseboards. Was to be a spring time project in this cabin I built but then our world was turned upside down so everything was put on hold.
Little Dauntless loves oak. Even though the stove looks like it's consumed most of the wood that was in there, it could run like this for several more hours without touching it. This is my window thermometer so the room was probably more like 74. It went down to -11 that night.
Cat probe sits perfectly in the middle. Air control at 70%.
For such a little stove, it loves to cruise.

 

[badgerfire]

So I'm wanting to get one of the fancy cat thermometers for my VC Dauntless from Auber Instruments.

A couple questions - are these the right things to get?

Is there an installation guide anywhere for how to set this up with a Dauntless? I have saved a couple threads on here where people are discussing these thermometers so I could probably just piece it together from there...

In an "explain it to me like I'm five" situation - the "thermocouple" (WRNK-191) goes in the stove where the current thermometer is and then some wire(s) come from that to the AT100TC thermometer and that displays the temp.

What is generally a good operating range for the cat? Reading the VC Dauntless manual, it says it starts working at 500F but no upper range and of course the "thermometer" included with the stove doesn't have numbers (just a white shaded zone labelled "Operate Catalyst"). Once we get this thing working, I want to have some sort of idea what an optimal range is. 800-1000?

Thanks!

 

[Turbo89]

So I'm wanting to get one of the fancy cat thermometers for my VC Dauntless from Auber Instruments.

A couple questions - are these the right things to get?
View attachment 336188
Is there an installation guide anywhere for how to set this up with a Dauntless? I have saved a couple threads on here where people are discussing these thermometers so I could probably just piece it together from there...

In an "explain it to me like I'm five" situation - the "thermocouple" (WRNK-191) goes in the stove where the current thermometer is and then some wire(s) come from that to the AT100TC thermometer and that displays the temp.

What is generally a good operating range for the cat? Reading the VC Dauntless manual, it says it starts working at 500F but no upper range and of course the "thermometer" included with the stove doesn't have numbers (just a white shaded zone labelled "Operate Catalyst"). Once we get this thing working, I want to have some sort of idea what an optimal range is. 800-1000?

Thanks!

it looks like you picked the meter and added a sensor option, so you don’t need to buy another sensor.

There’s lots of folks on here with more experience than me, but folks seem to like to keep temps below 1650 as to not damage the catalytic element and run them between 1000-1450. I belthe VC manual says they start to be active above 800 deg, but I’m going from memory.

I posted some pics a few weeks ago about installing one in an Encore. Perhaps they’ll be useful for you, but it’s a different stove?

 

[Woodsplitter67]

So I'm wanting to get one of the fancy cat thermometers for my VC Dauntless from Auber Instruments.

A couple questions - are these the right things to get?
View attachment 336188
Is there an installation guide anywhere for how to set this up with a Dauntless? I have saved a couple threads on here where people are discussing these thermometers so I could probably just piece it together from there...

In an "explain it to me like I'm five" situation - the "thermocouple" (WRNK-191) goes in the stove where the current thermometer is and then some wire(s) come from that to the AT100TC thermometer and that displays the temp.

What is generally a good operating range for the cat? Reading the VC Dauntless manual, it says it starts working at 500F but no upper range and of course the "thermometer" included with the stove doesn't have numbers (just a white shaded zone labelled "Operate Catalyst"). Once we get this thing working, I want to have some sort of idea what an optimal range is. 800-1000?

Thanks!

This looks correct, I didn't look it up but before you order make sure your k type thermocoupler is to 2k degrees.. as the sell the same one only to 1000 I believe

 

[Megunticook]

What is generally a good operating range for the cat?

According to Condar, the North Carolina company where I get my cats from, 1000-1700 is the operating range. I've followed that (mostly!) and my cats have lasted years (except for year 1 when I blew through the cat out of ignorance). They say to go ahead and close the damper at 500, but it takes a while to get the probe up to 500 on my Encore with the damper open, so I generally close it when griddle reaches 500 and then the cat probe will reach 500 in a minute or two. Usually after about 5-10 minutes I'm up at 1000 and I try to settle things in at 1000-1300.

 

[badgerfire]

Super! Thanks for the replies! I'll get it ordered (make sure to just get one sensor and a thermocouple that is good to 2k).