Vermont Castings Burn Observations

[Smokey Da Bears]

I also rake them around with the Defiant and try not to overload the back. @AsylumResident I like those percentages. Will you be providing calibration weights for our scales and the appropriate PPE? (sorry - I work in a laboratory)

With all this catalyst talk over the last 2 weeks, the algorithm has been strong! All I'm getting on social media lately is pictures of crumbling catalysts (all stove models, not just VC) and in the VC groups they are specifically talking about pulling the catalyst and going full secondary through the refractory. Anyone else? Or am I losing it?

 

[AsylumResident]

I am thinking about cleaning my flue sometime soon for a fresh start and then running the rest of the year without the cat. Then I can compare the first part of the burning season with the cat and the second part of the burning season without the cat. The real world is not a controlled laboratory setting so this won't be a perfect apples to apples comparison since there are other variables out of my control but it will at least give me an idea of what to expect in my flue if I decide to run without the cat.

 

[Woodsplitter67]

I am thinking about cleaning my flue sometime soon for a fresh start and then running the rest of the year without the cat. Then I can compare the first part of the burning season with the cat and the second part of the burning season without the cat. The real world is not a controlled laboratory setting so this won't be a perfect apples to apples comparison since there are other variables out of my control but it will at least give me an idea of what to expect in my flue if I decide to run without the cat.

One of the things you need to watch for with out the cat is your stove stalling. To avoid this you can't turn your primary air all the way back. You will need to keep the air open. Your flue temps will drop with out the cat and the air all the way closed.

 

[bullittman281]

Howdy,
I like the accurate weight distribution for maximum performance and agility. I understand they handle better closer to 50-50..... Or was that mass centralization???

The stove stall is a real concern and a catalyst's ultimate trophy if they can be made to work. This is their magic. Look at the likes of blaze king. My first knowledge of "down draft" style stoves was the Lopi Leyden and its magnificent spec sheet. Time proved that stove very hard to run and fragile as well. Operators at the time had a hard time with them stalling and leaking tar as is smolder to death, A cat that is operational can prevent that.
In other news I have thermocouple parts on order....

 

[Woodsplitter67]

Me personally I wouldn't be doing long burns or overnight burns without a cat.

The reward of having the cat helping the stove burn correctly out ways anything else. We've all experienced high cat temps and some have even warped the cat. Other then that nothing else happens. I don't understand why people panic.

Keep the stove pipe clean, burn dry wood and if the cat goes to 1700 oh well.

If you have any concerns keep a stick of chimfex handy. Everyone should have one anyway

 

[arnermd]

Merry Christmas all, I hope you all had a peaceful and warm day.

Some general observations over the past week, nothing too shocking I think.....

• I have been running my old metal cat, I suspect it is mostly, if not entirely inactive.....
• Raking coals evenly kept my peak cat temps lower as opposed to piling them up at the secondary inlet, which frequently resulted in temps over 1600. Level seems to work best as @Woodsplitter67 has said before....
• Sometimes I struggle to get the secondary temps up over 650.... but other times it goes right to 1100 - 1200 no problem.
  • This morning I opened air to heat up the coals, raked level, reload at 450F, full load, 100% air
  • STT climbed up to 650 lots of flame in the box.
  • Cat temps only go to 550 - 600, even after sitting for an hour, fair bit of smoke out the stack.
  • I suspect there may not have been enough coals to get secondary combustion. Maybe on this reload I should have raked coals to the back.....
  • After 3 hours secondary is up to 750F with air set to 60% open, STT = 550.

Always something.....

 

[bullittman281]

Good Morning.......
Temperature measuring is real!!
The setup is home brew so take the accuracy for what you think it could be....
The probe is a type K from Auber instruments, the amplifier is a MAX31855 being run by a Raspberry PI pico and interfaced to a regular raspberry pi but any computer running thony could interface with the controller. The end plan is a small standalone thermometer with digital display. I wanted results now.......


The probe is in the flue collar adapter directly above the stove. This spot was chosen because there was already a screw hole and I'm lazy.
So, after a couple of days testing the results of what I see are:
The initial bypass kindling fire I see temps 650 on up. I'm sure with enough wood things could get hot enough to melt.
Bypass closed I'm seeing a minimum temp of 650-700 degrees, with seconday burn.
Early in a burn, a secondary stall leads to temps of 350 or less. I took action to not smoke the hole town out so I don't know how low it would go. This was with plenty of active fire. I did not get images.
Once everything settles in outlet temps run 750-800 degrees.
Below are images/samples from today's start. These were all taken after the second reload with a hot ceramic burning and a good amount of coals. Current air temps is around 10*. This is the first time I'm been home to run the stove when its this cold. Most of my burns are in the 30s and 40s or even warmer.

After closing the bypass and the air control the stack temp jumped up to ~1050-1100 degrees. Toasty. Burner noise was obvious. This is normally as closed as I can get the primary without back puffing. After a bit I closed it one more to 6 clicks closed. Again, typically this is a no-go because of back puffing but it settled down and quieted down. The EGTs settled to 850 and as I type this have drifted down to 750. It will coast along there until it runs out of wood. I may give it a click more air in a bit as I am NOT interested in back puffing the house full of smoke, but right now there are still some active flames so its ok for now..... The picks show what its doing.

In this setup I would be surprised to see a catalyst having much work todo and should not be a great deal hotter that what I'm seeing for temps, assuming all the combustion can happen before the catalyst. My stove isn't drilled for the cat probe so my temps will be somewhat lower that right at the throat of the burner where the catalyst would sit. Not sure if any of this proves anything or not or if anybody else even finds it interesting.

There's more to come......
Up next is surface temps. lasers vs surface thermometers vs a thermocouple.