Medium-size Wood Stove for Super Insulated House in Vermont
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The one thing I would say is that for wellinsulated places, that keep their heat a long time, having a BK (30 model) that you loaded up and then get more solar heat gain than you expected, your home may get too hot, for long.
A stove in which you can burn a smaller (shorter) fire may them make more sense.
Of course you don't have to load.a BK full, but I think that a more nimble stove that can a bit more easily be stopped and started, or that may function well for short and small fires, may have a bit of an advantage.
A stove in which you can burn a smaller (shorter) fire may them make more sense.
Of course you don't have to load.a BK full, but I think that a more nimble stove that can a bit more easily be stopped and started, or that may function well for short and small fires, may have a bit of an advantage.
That's why I went with a BK PE32 for my well sealed and insulated new house in Oregon. The builder/designer was concerned that a stove would make too much heat. The BK can be turned down low, so I'm not limited to running it on only the coldest days.
Boy this sure sounds like a good place for a Soapstone cat stove!
That or keep your current stove, and add another small stove in the other end of the house...2 stage heating!
And I agree that 35k btu sounds awful high...our house is just an old 2k ft (3 with basement) brick cape cod, with average insulation, and we get along just fine with a 45k BTU wood furnace
That or keep your current stove, and add another small stove in the other end of the house...2 stage heating!
And I agree that 35k btu sounds awful high...our house is just an old 2k ft (3 with basement) brick cape cod, with average insulation, and we get along just fine with a 45k BTU wood furnace
What in particular makes your home super insulated, is it made from ICF forms? Or are the walls thicker than standard 2x6? More ceiling insulation?
One that is easy breathing.
I think an easy breathing stove that also runs well (clean) on a small load, is ideal. A stove that runs well low may lead to a "shoot, I now need to run thru this load for 12.+.more hours when the sun exposure already keeps me warm".
Of course one can always open a window too.
I think an easy breathing stove that also runs well (clean) on a small load, is ideal. A stove that runs well low may lead to a "shoot, I now need to run thru this load for 12.+.more hours when the sun exposure already keeps me warm".
Of course one can always open a window too.
My Jotul 3CB was and easy breathing stove that ran clean on a small load. Heated fast, started cooling as soon as the flames died. I agree that a stove like that might work well. Now that I’m on the high thermal mass side of things, I like this and think it could work. I think the trade off is constantly trying to turn on a dime with a stove like my Jotul vs cruising along, make a fire now and then, don’t sweat it so much. On the other hand you’d definitely have to not get carried away if it was about to get sunny and warm.
When I had my passive solar superinsulated house with masonry stove, I definitely paid very careful attention to the weather forecast, both expected temperature and solar. It was more along the lines of saving wood, getting away without making a fire rather than worrying about being too hot. I don’t remember ever being too hot when making a fire when I shouldn’t, but I do remember, “alright, I can skip a fire.”
When I had my passive solar superinsulated house with masonry stove, I definitely paid very careful attention to the weather forecast, both expected temperature and solar. It was more along the lines of saving wood, getting away without making a fire rather than worrying about being too hot. I don’t remember ever being too hot when making a fire when I shouldn’t, but I do remember, “alright, I can skip a fire.”
That's in the same general size as his Rais and unfortunately discontinued. It's been stated that the Rais has not been able to keep up with the heatng needs after the addition.
This person is most certainly doing an over-fudged Manual J calculation which will way overestimate your real heating need. Super-insulated house with 1700 square feet should be well served with a 2 cubic foot firebox with twice a day loading. I'd go with a cat stove if it was my choice.
Walls are built with double rows of studs with several inch gap in between as a thermal break. There's very few places in the framing where cold can find a solid piece of wood (stud or rafter, etc..) and travel from outside to inside. Walls are 10-12" thick of blown cellulose (initial build was 10" walls roughly R-37, Addition was 12" thick walls roughly R-44).
Similar idea with older house rafters having drop down extensions with cellulose in between. And addition has an unusable attic.. with over 24" of loose fill cellulose. Blower door tests have shown very high performance for tightness. Biggest heat loss is just the cheaper windows (still not cheap) I put in 10 years ago.
It certainly didn't feel like the math matched up with real-world experience in the house.
The RAIS Mino II is so small (and 12" or smaller length logs) that even if you load it up to the max it'll be down to coals within maybe 90 min or less. So even if you're home & stoking it every 45 min all day it's still not going 24 hrs/day. And even then, we were still not able to get the entire house up above 70 in the coldest days of winter.. and waking up to high-50s in certain areas of the house.
So a stove that's capable of double the RAIS for BTU seems like it would easily get us there.
I am leaning toward exactly what you suggested.. a 2 cubic foot cat stove.
I think you'll be well served by that. For a comparison, I have a 1750 square foot very well insulated 2-story home (18,000 BTU heat loss at 0 degrees F outside temperature). My small Woodstock Keystone will carry about 80% of that load with the upstairs being 5 degrees colder than downstairs (with no supplemental heat). In a power-outage pinch, I could heat the house with this stove on a cold day to about 63 degrees steady-state. I use a little supplemental radiant floor heat upstairs mostly.
I've been watching this thread with some interest. I think that @DBoon has given some great advice from his experience with a cat stove, and @begreen has made two excellent suggestions of a Woodstock Fireview or a Blaze King Ashford/Chinook/Sirocco stove. For the Blaze King, all three stoves have the same firebox configuration, but the external cladding is different depending on the preferred aesthetic.
I just wanted to chime in and ask what sort of hearth you have in place for the Rais Mino and what kind of clearances you can comfortably achieve for a larger stove? It might be helpful as you are considering a new stove to mark out with painters' tape in your existing space what would be required. I would even suggest a cardboard box mockup, but I believe you're still burning a stove there right now, so obviously that wouldn't work while it's still cold out.
I just wanted to chime in and ask what sort of hearth you have in place for the Rais Mino and what kind of clearances you can comfortably achieve for a larger stove? It might be helpful as you are considering a new stove to mark out with painters' tape in your existing space what would be required. I would even suggest a cardboard box mockup, but I believe you're still burning a stove there right now, so obviously that wouldn't work while it's still cold out.
Current hearth is slate tile. Heat shield with copper face is 36” wide. Looking at Ashord 20 manual, it looks like the only adjustment I’d need to make is bringing tile out more in front. And I’ve already got the 4” intake coming in behind this RAIS a few inches off tile floor.
One thing I’m wondering about is minimum clearance on rear side. Manual says 6.5” to combustible rear wall. But what about to a heat shield with 1/2” concrete board & 3/4” air gap behind it with open channels at bottom & top? Could I get away with 3-4” to heat shield? (This would allow chimney pipe to remain straight from roof to stove)
Reducing the rear clearance using a ventilated wall shield would require written permission from the local inspecting authority.
Not sure if I should be starting a new thread to ask this question that's slightly unrelated to where this began. But will stick it here and hope I might get feedback.
I had a suggestion from someone in Vermont with an older Napoleon stove to install one of these cut-off gates in the outside air intake. He claims closing it at night (before sleep) helped temps stay warmer in the room overnight, and closing it did not prevent the fire from still going well for the first half of the night. But I have a feeling that for some well-sealed stoves that 99% rely on the outside air intake, closing this would only be advisable if the stove is fully cold.
Do many of you that have exterior air intakes use anything like this?
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YOu have BK and RAIS in your sigblock. Not sure for what stove you propose this.
For the BK I would not do that; this may work with a leaky stove, but your BK is not (should not be). If leaky it may suck in enough air to close this thing and have a decent burn - but using inside air, meaning the benefits of your outside air kit are not used.
Your BK is (should be) so tight that if you restrict the air coming in with something like this, you'll end up choking it too much.
Now it's not bad to have this thing installed, as long as it's open while burning. In summer when you're not burning, closing off the outside air can be a good thing.
But air inlets are generally sized to provide the air needed for the stove. Restricting that (severely) with a valve like this while burning won't be good - unless your draft is far, far too high (leading to too much air flow, that you could cut down on by *partially* closing that valve - not completely).
That's my $0.02
For the BK I would not do that; this may work with a leaky stove, but your BK is not (should not be). If leaky it may suck in enough air to close this thing and have a decent burn - but using inside air, meaning the benefits of your outside air kit are not used.
Your BK is (should be) so tight that if you restrict the air coming in with something like this, you'll end up choking it too much.
Now it's not bad to have this thing installed, as long as it's open while burning. In summer when you're not burning, closing off the outside air can be a good thing.
But air inlets are generally sized to provide the air needed for the stove. Restricting that (severely) with a valve like this while burning won't be good - unless your draft is far, far too high (leading to too much air flow, that you could cut down on by *partially* closing that valve - not completely).
That's my $0.02
EbS-P
Minister of Fire
I would only close completely when the stove is cold. I might be tempted to use it as a damper but that would take some experimenting.
If I closed it I for sure would have a CO detector in the room.
What about wrapping the OAK with mineral wool insulation so condensation isn't a constant thing in winter? I realize this would be putting insulation basically in contact with the stove.. but that extreme rear/bottom spot on the stove shouldn't be that hot if it's already in contact with a flexible 4" pipe.
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