Vermont Casting Aspen C3 - How hot should it run

[MikeGraz]

wjohn
I was looking at your pics of the damper in the stove. Interesting that both the primary and secondary air have holes so that even with the stove damper shut, a fair amount of air would still be allowed into the box. I guess this is to keep the stove hot to burn/dilute the smoke and pass emissions.

FYI 3" double wall pellet stove pipe (3.5" OD) fits the outside air intake on the stove. VC simply states a 3" pipe, which is misleading

I thought about a blast gate, but don't have much room and didn't want plastic close to the stove. I found an inexpensive 3" aluminum blast gate (Woodstock W1141) and have ordered one to install in my outside air intake.

As you use your stove, let me know how it works out and what kind of temps your seeing.

 

[wjohn]

MikeGraz, glad you found my pics in that thread. I have not had very large fires so far but I don't think I would dial the air down any further even if I could, based on my observations of the fire once the cooktop is up to 600+ degrees. I may have to take a peek back there next time I remember and see if I can figure out about what temp corresponds to the bimetallic spring allowing the damper to completely close on the air intake. I guess I am not sure it is completely closed yet once up to that 600+ at the cook top or not. As you said there is still some amount of air let in through those holes; I guess I am not that concerned about it but I come from a household that ran an old Baron welded stove and we never completely closed the dampers in the front door, ever. I'll reserve judgment until I get a big long fire or two out of the Aspen C3.

Thank you for the tip on the pellet stove pipe! I never even thought to try that. As you said the manual just says 3" and I sure as heck wasn't coming up with any 3" stuff that would fit. When I redo my air intake I will get at least a piece of that to connect to the stove inlet. I've been keeping tabs on the plastic blast gate and I'm not at all worried. I have more than double VC's minimum clearance from the stove to the wall though, and on top of that it's a corner installation.

So far I have not seen more than 650ish at the center of the cook plate but with those small barely 1/3 full fires. We are supposed to be back in the 60s and 70s here for the next week so it may still be a while before it's cold enough for me to actually load it up. I'll be curious to see your temps going forwards too. We'll both have to post back here. So far I am very pleased with my stove.

 

[EddyB]

Thank goodness I found you guys! I just had my Aspen installed a few weeks ago and it's been an interesting experience so far. I don't have an external draft connected on it so I can see/feel the draft door on the back. Basically what John has mentioned is pretty well spot on, except I haven't had a significant fire in it to go to those high 700-800 temps. Having said that, I'll share my experience. My stove is a corner installation meeting the clearance specs, 8 foot ceiling, double wall pipe and chimney totaling 14 feet. Also, I had a Napolean 1400 for years prior.

The "super-wool blanket", as they call it, does have a notch cut out of it near the front where the hot-plate is located. The probe for the thermostat is located just in front of the flu opening where the gases are exiting the stove. I saw about a 100 degree difference between the hotplate and back close to the flu opening using both an IR and stove top thermometer.

I have to say, the temps were definitely getting my attention as well. I'll come back to that. But for a reference, with a stove top temperature of 500 degrees by the flu (closer to 600 at the cooktop plate in the front), the lower half of the double wall flu reached 170 and the top half was 130. Did I see the temps go higher than that on the stove? I did. But, I haven't made a "mature" fire yet lasting more than 2 hours and the usual big chunks in it.

Just so you can compare, I've done several small burns to condition it and get the "smells" out of it from paint, etc. I paid close attention to the "behavior" of the stove each time. I was on my third small burn and could still smell the factory odors coming off it. A little better each time. The fourth burn was longer and hotter and saw the stove top reach close to 700 and then stabilize around 600. During all this, I would feel the draft door around the back.

One thing I noticed apart than the usual stuff that you experience when operating a wood stove. Yes, the door has to be just cracked open when starting and for awhile after that... and I mean JUST cracked open. Smoke came out any more than that. Once it was going (but still in the early stages of feeding it with bigger kindling) and no issues of it going out, a few times I closed the front door and watched the fire die down fairly quickly and stayed that way. I cracked it open again and it was fine. Then, with a good kindling fire going with some larger pieces (but still not fully mature with large chunks), I decided to close the door and wait. The flames died down significantly for a few seconds, and then it slowly came alive again and was consistent. It was burning well, no wild draft of a flame per se, but it was definitely going and I was quite satisfied with the result. I felt the draft opening in the back and the door was fully closed. The temperature seemed to stabilize around 550-600 (again with the condition that I haven't fully loaded it up with big chunks yet).

So, I think there is a sweet spot with that stove where you have to watch the temps closely and get that door closed as soon as possible, but at the risk of losing the momentum. I know this sounds kind of redundant because it's pretty well like any wood stove in terms of shutting down the draft and walking away. My old 1400 was quite forgiving that way. But, I think this particular stove is fussy and (IF you have a decent draft to begin with and dry wood), you should close the door as soon as you can and let it do its thing. I will update when I make a long burn into 2-4 hours with big chunks and see how it goes. One thing is certain, it gives off an amazing heat and cast iron stays warm for a long time. We love it. Whew, thank you for being here guys!

 

[SpaceBus]

Things will become easier as the winter gets colder and you use the stove some more.

 

[wjohn]

EddyB thanks for sharing your experience so far. Time will tell if the Aspen C3 will be a good stove but I am cautiously optimistic so far. It sure seems simpler than some of VC's previous stoves that ended up being maintenance nightmares, from what I've gathered. It does really put out the heat for such a small stove on so little wood.

 

[EddyB]

Look what VC provided me. We knew much of this already, but it validates what has been said about the system. But still no luck in getting “acceptable” temperature limits. They didn’t budge on that request. I reviewed every number and every word in the third party test document done a few years ago. They do reach temps into the 800s.
Did anyone notice any warpage in your refractor board? It was sitting perfectly flat on the side rails and the back when I got it, but it’s not doing that now. I’ll post a picture this evening.

 

[begreen]

EddyB, how tall is the flue system on this stove? Have you added a key damper above the flue outlet to reduce draft?

 

[wjohn]

Did anyone notice any warpage in your refractor board? It was sitting perfectly flat on the side rails and the back when I got it, but it’s not doing that now. I’ll post a picture this evening.

Thanks for sharing that VC documentation!

I have not noticed any warpage in my baffle so far. I just took a look. I have not had enough fires to say it won't happen, though.

 

[EddyB]

The flue from the stove to the ceiling is about 6 feet, then another 8 feet to the top outside. There is no key damper, in fact, supposedly there’s liability issues here in Canada and insurance as well if you use them on certain stoves that don’t require them or you “shouldn’t” use one and you have an accident with it. They don’t advise on a damper with this particular stove, even though people do install one anyway. So, I’m going to hold off and see how it goes. It was part of the reason why I got this stove so that it would be easy to operate with my better half because she isn’t really comfortable with wood stoves to begin with. So I figured this one would help address that concern. Having said that, I like the finer manual control myself and get it just right.
One thing I would consider using is what has been talked about in the forum and a limiter of some kind on the external draft intake on the back. Draft is not an issue here for me. If you could slow it down a little more, then I think it would cap those high temps at a more comfortable level. It’s getting colder here so it’ll be interesting to see how the performance goes. It should be better, but will that increase the temps even more with the increased performance. Time will tell in the coming weeks.

 

[wjohn]

I have still only run about 1/3 full (so I still haven't seen over 650ish at the center of the cooktop thus far) but I took some notes of temps and rear intake damper position in my install thread. Here's a direct link to the specific post for anyone's reference: Aspen C3 Temp vs. Intake Damper Position

 

[MikeGraz]

EddyB
Thanks for the VC documentation. Wish I had seen it earlier. VC should supply that with the stove. Don't remember for sure, but I don't think my thermal probe is showing above the insulation blanket. My stove definitely runs hot if left on its own, but now I have it under control.

Installed an aluminum blast gate on the cold air intake. By varying the opening I can control it to any temp I want. Before I installed the gate, I marked it to determine precisely how far it is open. Have run it a couple of times checking the temp every 10 -15 minutes by IR. At just under 50% open the stove seems to be running well. Stove top temp runs 500 - 550, center of cook top 550 - 600, flue temp up ~ 18" 350 degrees.

I have a key damper in the flue, but leave it fully open now. I would rather be able to control intake rather than outlet. It may not matter either way, just don't like the idea of closing off the flue. The blast gate also give me a total shutoff of the intake, if I need it

I also set up a small fan by the stove and tied it into a temp controlled outlet. Setup seems to be working will. I still have only loaded the stove about 1/2 way. Waiting for colder weather for the final test, but am pretty confident this setup will work

 

[EddyB]

That looks great! I think we may be on the right track regarding controlling the cold air intake a little more. A blast gate may do just the trick.
Is the fan meant to provide some extra draft towards the cold air intake when the stove cools down and needs a little more air to burn a little more, even though you may not be around or asleep to manually open up the blast gate?

 

[SpaceBus]

I probably would worry about putting a damper on the flue rather than controlling the intake air.

 

[MikeGraz]

The fan is simply to move more hot air around the room once the stove gets hot, instead of just relying on natural circulation. The air intake runs thru the blast gate and then out thru the outer wall so that I am drawing in outside air, not air from inside the house.

 

[EddyB]

So up til now, I’ve been kind of limited with being able to do a prolonged burn with the new Aspen because of renos being done in the house. I’ve done around 6-7 fires starting with 3-4 smaller ones to burn off the paint, etc. which I described in an earlier post, and noticed the high temps. Those experiences really gave me a strong sense of how the stove behaves and how to operate it with little problems. No damper, no external air intake, lots of draft. Lack of draft is definitely not an issue. You can feel it with ease at the intake on the back.

I’ll start with the fact that the stove is truly simple to use, love the heat, love the look, etc. Would be very content just based on that.

Last night really caught my attention and I would like to get feedback from the Aspen owner’s especially please, because it would be a deciding factor as to whether or not the retailer & VC needs to address it.

I had it started nicely, and after the flu was conditioned, it was a nice slow burn. Temperatures didn’t jump too quickly and eventually came up to around 500-600 stove top. During all this, I was feeling the position of the flap on the back at the air intake and it was gradually closing. It stabilized there for awhile while feeding it a couple of smaller chunks at a time, and at no time were the flames slowing right down to a trickle as what some people remark when the stove is up to normal temperature. Eventually, I put in a couple of larger chunks for the night. They caught right away and the door was closed. I felt the flap and it was around 80-85% closed.

Eventually, the stove got up to over 850 degrees and the flames were not slowing down to that barely visible trickle that Ive heard about. I felt around to the flap, it hadn’t changed. Still about 80-85% closed. At this point, I would assume that it should be all the way down. As a footnote, the stove has probably expanded so much with some of those hotter burns that have taken place up till now, that when it was cooling down last night (and still talking around 500 degrees), the noise from the contraction was quite something, which makes me think that those really high burns really pushed the cast iron and joints… maybe.

I know that some people have dampers and even blast gates at the intake. According to VC and the retailer, if you have decent draft, you shouldn’t need any modifications like those to control things.

So, before I go and really push the issue, I was wondering if the Aspen owners could tell me if the flap on your cold air intake is completely closed at the hotter temps on your stove. I know some of you have external air intakes and can’t really feel the gate to see how open or closed it may be, but if you do know, could you give me some feedback. It would be so appreciated.

Perhaps all that needs to be done is disconnect the chain, lengthen or slacken it a tad, then reconnect it. Not sure. It won’t be me doing it because it’s a brand new stove and the retailer should be taking care of the problem.

There’s my story and you guys have been instrumental in getting things to this point, so if you have some data to provide regarding the gate at the cold air intake and whether or not it’s fully closed at peak, please share. I’m feeling a little disillusioned because I love the stove and don’t need this right now. Thank you so much Everyone!

 

[MikeGraz]

Eddy
I have the OAK installed so I can't see the damper. My experience with the stove was similar and I assume it was because the flap either didn't close soon enough or didn't close completely, that is why I started this thread. Even with a partial load the stove took off. My IR themometer only goes to 750 degrees and it was reading over that. Putting a damper in the flue only helped minimally. Putting a blast gate on the intake got it under control.

If I only load 1 or 2 logs I can leave the gate open. Anything more than that and I close the gate down to about 25% and then let the thermostat do its thing.

I contacted VC several times about this and never got any useful information. Contacted my dealer and never heard back from them. Told VC I never heard back from my dealer, and they had no response. I am very unhappy VC customer support.

Its very unfortunate because by controlling with the gate, I am very happy with the stove so far, but should not have to do that.

 

[EddyB]

Eddy
I have the OAK installed so I can't see the damper. My experience with the stove was similar and I assume it was because the flap either didn't close soon enough or didn't close completely, that is why I started this thread. Even with a partial load the stove took off. My IR themometer only goes to 750 degrees and it was reading over that. Putting a damper in the flue only helped minimally. Putting a blast gate on the intake got it under control.

If I only load 1 or 2 logs I can leave the gate open. Anything more than that and I close the gate down to about 25% and then let the thermostat do its thing.

I contacted VC several times about this and never got any useful information. Contacted my dealer and never heard back from them. Told VC I never heard back from my dealer, and they had no response. I am very unhappy VC customer support.

Its very unfortunate because by controlling with the gate, I am very happy with the stove so far, but should not have to do that.

Thank you so much for the feedback Mike. It really put it into perspective what’s going on. The stove is the perfect size and normally doesn’t require a lot of work, and the price point is just right versus some of the more expensive ones of a similar size. The North-South orientation is perfect for our space. It’s such a shame.
So, I’ll see if others share their thoughts and see what the retailer says (good luck with that one I guess) and go from there. Thank you!

 

[wjohn]

EddyB, you'll get better responses if you keep your posts in one spot and don't duplicate (I noticed you also posted in my Aspen C3 installation thread). I will reply here since this thread is pretty well focused on the stove temperatures.

My intake damper is completely closed - like resting completely flat against the big plate it's mounted on - by the time my cooktop center hits 550 degrees or the insulated spot between the cooktop surface and the flue exit hits 470 degrees. I would expect this to vary somewhat depending on how fast the fire gets up to temp from cold as the probe for the bimetallic thermostat that pulls on the intake damper chain is sitting between the insulation blanket and the top casting of the stove, so really it's whatever temperature that gets up to that sets the flap closing. I am reading from the outside of the stove so it's a bit of a secondary reading and there's somewhat of a delay.

Regardless, it should be completely closed at higher temps so that the only air that can get in is through the two holes in that intake damper. Sorry for the terrible pictures but the one with my finger in it is what it looks like when the stove is up to temp and that intake damper is dropped flat against the big plate. I have verified this visually and carefully with my fingers on my last couple of burns (the intake stays pretty cool at least on stove startup... No promises after it's been burning for hours, ha).

If your thermostat/chain are not letting it close down completely flat then I would say something needs to be fixed.

 

[wjohn]

And I agree the blast gate shouldn't be necessary as long as you have close to the ideal chimney height (16' from the floor the stove is sitting on to the chimney cap, per the current manual). I added one in mine per some feedback from members on here just in case I get a crazy day where the wind is forcing a ton of extra air into the cold air intake, and need to reduce that a little. Since the holes are fixed size when the intake damper of the stove fully closes, it makes sense that if you have a lot more pressurized air being forced into them (say from a 40 MPH wind, instead of a 0 MPH calm day where the only air going into the stove is being sucked in naturally by the fire/draft) you may need a way to cut that down.

I guess the analogy to a windy day is like having a supercharger on your air intake, pressurizing the air. It can push in more air than the stove needs and increase the burn rate, and potentially lead to an overfire. For $4 or whatever the black ABS blast gate was it seemed silly not to mount it in the wall. I wouldn't think a blast gate or similar would be needed with no outside air intake as there isn't any way for the intake to get pressurized from wind if it's just hanging out inside your house, sucking in room air. BUT, that intake damper flap needs to be completely closing. I am not a VC design engineer but it makes sense that the holes in the intake flap are sized for the long-term, up to operating temp burn rate so that the flap is closed and there is a set amount of air coming in through those holes.

I haven't had to contact VC customer support yet but that is very disappointing to hear. Maybe they are scared to point people to the previous EPA test report since they are supposedly waiting on retesting due to some sort of missing information from the 3rd party test lab. I am still taking those temperatures as references, albeit not 100% sure they were measuring over the insulated or uninsulated (cooktop) area of the top of the firebox. I still haven't had a proper sized fire in mine yet to push even the cooktop temps past 650ish yet.

 

[EddyB]

Thank you so much for the feedback on your experience. Everything you’re saying makes perfect sense and you’re right, it should be closed and I am 100% certain that it is not fully closed, and it shouldn’t require those additional mods to get it into an acceptable operation.
I was talking to the retailer manager today and he said he sells a lot of Aspens, which is true because I’ve seen their storage of them when they’re delivered and sold. He’s never had any issues that I described. So, it’s possible I’m dealing with a faulty thermostat or assembly within the stove. His rep who deals with VC is going to call me Monday. It’ll be interesting to see what he says.
Thank you for that very helpful input and yes, I’ll stay on the designated thread for our issue. Have a good warm weekend!

 

[MikeGraz]

Sound like your dealing with a good retailer. Keep us posted, would love to hear how it turns out.

 

[EddyB]

While I’m waiting to hear back regarding the temp situation, for the Aspen owners, before going to sleep for the night for example, how many moderate to large chunks do you thrown in? Just so my expectations are not unrealistic! Thanks!

 

[MikeGraz]

Eddy
At night I usually load 3 pieces, which fills the Firebox about 3/4 full. Close my blast gate to about 25% open. Stove will reach about 500 degrees on this setting. Overnight for me is about 7-8 hrs. In the morning the stove have a little bit of red coals left and the temp of the stove is about 100 degrees. A little bit of kindling and a couple small spilts, with the door barely open for a couple minutes, and it starts right up

Hope this helps, Mike

 

[EddyB]

Mike, this sounds more like it. Obviously something is amiss. I’m happy to hear that, even though you have a damper and a blast gate. The irony in all this is up till I got the stove, almost all my homework ahead of time consisted of reading about people complaining of not enough air going in, especially with all the references to the excess cement getting into the air pathways during manufacturing of the earlier C3s that came off the assembly line.
So, the dealer is going to come and somehow extend the chain coming from the thermostat at the flap in the air intake. Not sure if there is enough slack there to do that, but that’s the plan I guess. He thinks that should allow the flap to sit down all the way closed. Then we’ll take it from there. But, if I can get that much wood into the stove without causing a major increase in temps again, then I will be very content. Thanks Mike!

 

[MikeGraz]

Eddy
Last night was 18 degrees, so I did a full load, 4 large pieces of wood. Set my blast gate to about 25% open. Stove got hotter than I would like, (720 degrees on the cook top, flue temp at 400 degrees) about an hour into the burn, so I closed the gate a bit more. In the morning, 9 hrs later, stove was still at 100 degrees with a little bit of red coals left. Will have to try initially closing the gate a little more to try and limit the max temp. These stoves definatly throw off some heat, 82 degrees in the room where the stove is located. The room is 24 ft x 16 ft.

Let me know what info you get from your dealer and how it works out lengthening the chain. I assume he will have to take the plate off the back of the stove to access the thermostat and chain.

I am very curious to find out how hot other peoples aspens C3 are getting with a full load. If anyone has that info, please let me know.