Vermont Casting Aspen C3 - How hot should it run

[wjohn]

I think the steel top hit 900-950 easily at the hottest point, but the glass top hits above 1000f. My Morso gets up to 800 sometimes, but I've stopped measuring STT and just go by flue temps now, and I don't measure anything on my cooker. The Morso has an insulated blanket over the whole length of the firebox, so I'm not surprised I have a bit lower temps despite having such a similar design.

The Aspen C3 has a single piece cast stovetop. There is an insulation blanket under it except for the front, where it has a cutout that matches the shape and size of the cooktop circle, so that area gets direct heat as it comes up around the baffle. Your 800 on your 2B lines up pretty nicely with the hottest stovetop temp I have measured over the insulated area.

Sounds like maybe the temps aren't unreasonable when compared to what you have seen on your stoves. It would still be good for us Aspen C3 owners if we could get confirmation from VC/HHT on where to measure stovetop temps and what is acceptable.

 

[Todd]

My little 602 has seen hot plate temps of 900+ and is usually 100-150 degrees less between it and the flue collar.

 

[72Rover]

While I have no knowledge of the Aspen and it's operating temps, 750 seems pretty hot. I have been using a VC Resolute for 42+ years and by my estimates, it has consumed 80+ cords of wood. (It stands inside my fireplace, with a little VC-branded 'muffin' fan moving air around the firebox. The still-working fan is also 42 years old....) More important would be the stack temp - or even the areas behind the insulation, as opposed to the cooktop itself.

What were the fuel and draft conditions when running hot? Small, very dry wood with a brisk breeze increasing draft? From what I gather from a cursory search of the web is that the Aspen's major complaint is that the air damper came improperly adjusted *from the factory*. Only a few factors can cause any stove to run too hot: an increased draft, too much air or tinder-dry wood. Many folks bought their Aspens when the original owner had no idea how to adjust/fix the draft issue. The automatic air damper on my Resolute is it's *best* feature. When properly 'tuned', I only see wiggles of heat vapors and an occasional wisp of smoke exiting the stack. I've got 20+ feet of stainless pipe inside a tile-lined brick chimney, so draft is outstanding....

Other than my '72 Land-Rover, the Resolute is the best purchase I have even made. Bought it even before I closed on the house. I did have to do a major rebuild three years ago, but I'd expect it would be good for another 40 years. Me, not so much....

Cheers

 

[wjohn]

While I have no knowledge of the Aspen and it's operating temps, 750 seems pretty hot. I have been using a VC Resolute for 42+ years and by my estimates, it has consumed 80+ cords of wood. (It stands inside my fireplace, with a little VC-branded 'muffin' fan moving air around the firebox. The still-working fan is also 42 years old....) More important would be the stack temp - or even the areas behind the insulation, as opposed to the cooktop itself.

What were the fuel and draft conditions when running hot? Small, very dry wood with a brisk breeze increasing draft? From what I gather from a cursory search of the web is that the Aspen's major complaint is that the air damper came improperly adjusted *from the factory*. Only a few factors can cause any stove to run too hot: an increased draft, too much air or tinder-dry wood. Many folks bought their Aspens when the original owner had no idea how to adjust/fix the draft issue. The automatic air damper on my Resolute is it's *best* feature. When properly 'tuned', I only see wiggles of heat vapors and an occasional wisp of smoke exiting the stack. I've got 20+ feet of stainless pipe inside a tile-lined brick chimney, so draft is outstanding....

Other than my '72 Land-Rover, the Resolute is the best purchase I have even made. Bought it even before I closed on the house. I did have to do a major rebuild three years ago, but I'd expect it would be good for another 40 years. Me, not so much....

Cheers

72Rover, you can read back through the posts to see the conditions. Nothing that should've caused this if it is indeed too high of a temp - low wind, actually short on flue length, etc. for my setup and it's even happened with some ~30% MC wood I tried just for kicks to see if it made a difference. There are two other guys who also posted on here who have different setups than I do.

But, hearing how hot the Jotul F602 and Morso 2B are getting from the above posts makes me think this may not be totally out of line. Maybe these small NS loading cast stoves are just designed for it?

 

[SpaceBus]

The Aspen C3 has a single piece cast stovetop. There is an insulation blanket under it except for the front, where it has a cutout that matches the shape and size of the cooktop circle, so that area gets direct heat as it comes up around the baffle. Your 800 on your 2B lines up pretty nicely with the hottest stovetop temp I have measured over the insulated area.

Sounds like maybe the temps aren't unreasonable when compared to what you have seen on your stoves. It would still be good for us Aspen C3 owners if we could get confirmation from VC/HHT on where to measure stovetop temps and what is acceptable.

When I first installed the Morso I was hitting it with my IR laser and checking magnetic thermos constantly. I even emailed the customer support at Morso NA and they gave me basically the same answer as HHT gave you.

I do think our narrow box stoves are just going to burn hotter than a larger stove. I think that is also part of the higher efficiency our small stoves enjoy over larger stoves, especially cat stoves. I can't recall exactly, but I think the Aspen C3 is rated 80% for efficiency, and my 2b classic is 85%, I think because of the large heat exchanger.

My stove also has the single piece cast top, albeit with holes on either end for the arch. My stove peaks right where the flames go around the baffle, usually a good 50-100f hotter than even just a few inches closer to the back of the stove. Unless you see it glowing I think you are good to go.

Speaking of glowing, my adapter from the double wall chimney pipe to my appliance collar on my cookstove was glowing in a few spots not long ago. With the high wind some embers set the film of creosote on the inside of the pipe alight. I'm glad I cleaned my chimney last week and installed everything to code!

 

[wjohn]

I can't find the 2020 2B Classic in the EPA database, or least not any test recent enough to have an efficiency value listed. The 2B Standard shows 80% HHV vs. 75% for the Aspen C3. Definitely impressive values for non-cat stoves. I bet the LHV lined up with the numbers you're remembering. I wouldn't doubt that the Classic could be even higher. I don't regret getting the Aspen C3 but would've loved to take a look at a 2B standard if we'd had a dealer around here.

The Aspen C3 manual just says stop if things start to glow. Guess I will keep on burning.

 

[SpaceBus]

I can't find the 2020 2B Classic in the EPA database, or least not any test recent enough to have an efficiency value listed. The 2B Standard shows 80% HHV vs. 75% for the Aspen C3. Definitely impressive values for non-cat stoves. I bet the LHV lined up with the numbers you're remembering. I wouldn't doubt that the Classic could be even higher. I don't regret getting the Aspen C3 but would've loved to take a look at a 2B standard if we'd had a dealer around here.

The Aspen C3 manual just says stop if things start to glow. Guess I will keep on burning.

I love the vagueness in a manual for a box that holds literal fire.

 

[wjohn]

I am at the winding down stage of "hitting it constantly with the IR thermometer" and saw 920 at the cooktop last night and 475 on the exterior of the stove pipe. We had 25 MPH sustained winds with 50 MPH gusts, so obviously I expect the stove to be cranking and I was keeping a close eye on things. I shut the blast gate I added on the intake down totally at that point until it dropped to 800 and then cracked it back open.

At 900 plus degrees at night with all other lights off, you can just barely make out a faint orange/red glow from the cooktop area. Everything else is ~800 or less and not glowing at that point. I think I'd prefer to keep it under 900 (and therefore not starting to glow) so that may be what I target as my max temp there going forward.

 

[SpaceBus]

I am at the winding down stage of "hitting it constantly with the IR thermometer" and saw 920 at the cooktop last night and 475 on the exterior of the stove pipe. We had 25 MPH sustained winds with 50 MPH gusts, so obviously I expect the stove to be cranking and I was keeping a close eye on things. I shut the blast gate I added on the intake down totally at that point until it dropped to 800 and then cracked it back open.

At 900 plus degrees at night with all other lights off, you can just barely make out a faint orange/red glow from the cooktop area. Everything else is ~800 or less and not glowing at that point. I think I'd prefer to keep it under 900 (and therefore not starting to glow) so that may be what I target as my max temp there going forward.

It was a windy night and it's just now calming down a bit. This morning I got distracted after reloading the stove and the flue got a bit hotter than I normally like. It's hard to manage a stove when it's constantly pushing 25 mph for hours on end. Sounds like you have a good system with the blast gate preventing the thermostat from letting things go too crazy. At least you get a quick response from adjusting the gate.

 

[wjohn]

I had some time to dig around and found the Jotul F 602 V2 EPA test report. They measured top temps of just over 1000 degrees. Plenty of the report is illegible due to poor quality scanning, so I can't see all the runs. Page 25 was readable and where I saw 1000.

Jotul F 602 V2 EPA Test Report

It's just an interesting reference point, not necessarily what is okay for an Aspen C3... But I would think they should be in the same ballpark at least, both being small cast iron stoves. Maybe this is further confirmation that the 920 degrees I have seen on my Aspen C3 is fine, and none of us should be that concerned, lining up with SpaceBus' and Todd's thoughts and input.

I checked the Morso 2B STT as well but it seemed to be much lower during testing - 770 degrees was the highest I could find (converted from 410 C in the report).

 

[MikeGraz]

Interesting reading. Its too bad that VC support is so unresponsive.

I am happy with my Aspen C3, although I use the blast gate on the outside air intake to control the stove top temp to 600 - 650 degrees. At these temps the stove throws off a lot of heat and the glass stays clean. If I let the stove control itself, as other have indicated, it gets much hotter and my room overheats. Have had a couple of -20 nights and the stove has done well. Load it up, let it reach 600-650 then close the blast gate most of the way . It will run overnight and still be warm in the am.

 

[wjohn]

I wanted to add something to at least check off the list for anyone that is experiencing very hot burns. Pull up your stove pipe and make sure your temp probe is not buried in ash/creosote. It will take longer to get up to temp because it's effectively insulating it, and therefore close the air intake later in the burn. Pics below show the accumulation that had flaked off the inside of my flue (and this was before any cleaning). I attribute this to my early cool break-in fires, an occasional piece of honey locust that probably had higher MC than I initially thought, and my general learning curve getting used to how to run the stove.

The stove will still sometimes briefly run up to around 900 on the cooktop but not for long and I don't worry about it, from the prior discussion in this thread. After cleaning this stuff up, it is noticeably quicker to shut the air down as the flue temp comes up when starting a fire.

I'd also note you probably don't want to vacuum this stuff out as that would probably destroy the insulation blanket. I carefully scooped it out with a narrow putty knife.

 

[SpaceBus]

I wanted to add something to at least check off the list for anyone that is experiencing very hot burns. Pull up your stove pipe and make sure your temp probe is not buried in ash/creosote. It will take longer to get up to temp because it's effectively insulating it, and therefore close the air intake later in the burn. Pics below show the accumulation that had flaked off the inside of my flue (and this was before any cleaning). I attribute this to my early cool break-in fires, an occasional piece of honey locust that probably had higher MC than I initially thought, and my general learning curve getting used to how to run the stove.

The stove will still sometimes briefly run up to around 900 on the cooktop but not for long and I don't worry about it, from the prior discussion in this thread. After cleaning this stuff up, it is noticeably quicker to shut the air down as the flue temp comes up when starting a fire.

I'd also note you probably don't want to vacuum this stuff out as that would probably destroy the insulation blanket. I carefully scooped it out with a narrow putty knife.

View attachment 291541 View attachment 291542

I use a very gentle ash vac on my insulation blankets and such. A shop vac would definitely be too much.