What size wood stove?

[WoodChuckDad]

WoodChuckDad:

Is the orientation of the house as showed in your plan (glazing to the North ?) If so, that would definitely contribute to a significant loss in energy efficiency... If the main glazing faces south, you would get solar gain and with a heavy concrete slab would be perfectly set up for passive solar.

I personally suggest you beware of Hearthstone. Make a very careful comparison between the way a Hearthstone and a Woodstock soapstone stove is built and its operating principle. A few hints: Hearthstone has single wall soapstone and their stoves work by the secondary air principle. Woodstock stoves are double wall soapstone and for the most part are catalytic. The combination of catalytic burn and double wall makes the woodstock stoves very easy to control for heat output and low stress. Anyone who knows how compromised the secondary air stove design is, when combined with how the emissions test is done for the EPA the stoves have a tendency to run away on a full load of fuel and be very difficult to control. When combined with 1 layer of soapstove, that frequently causes cracked stones and other air leaks, making the stove run away even more.

Most complaints I have heard about were not compensated for their damaged Hearthstone stoves since the factory regards overfiring as the fault of the owner, not inherent in the design and the nature of what one gets with a tall chimney that produces good draft under cold conditions.

I have had several secondary air type stoves and all have had the same runaway issues, its just that good quality steel stoves (NC or Pacific Energy) or good quality cast iron (Morso) survive overheating better than soapstone, especially single wall.

If you don't want a catalytic stove, look at the Pacific Energy T6 stove. It has a large firebox, the steel core of the stove is of high quality and the cast iron jacket promotes convective cooling of the stove which in turn makes a big convective plume of hot air in the house. I have a T5 which is the smaller model and it heats the upper 1300 sq ft of my home here in MI through the last few polar vortexes with -30F....

I have an Appalachian stove now. Catalytic. It's over 20 years old. I am leaning away from catalytic. The main room and front door face south, southwest The reason for facing that direction is the view of the mountains.
There is no central air system, we will be using ductless AC systems

 

[westcliffe01]

If you are set on a secondary air type stove, be sure to install a damper in the stovepipe as high as you can get it above the stove and still reach it. Also a probe style flue temperature gauge (not a surface thermometer) so that you are aware how hot the inside of your stove is getting. In really cold conditions with high draft, I have seen 1200-1500F with my stove with the air intake fully closed and the stovepipe damper fully closed. In such cases I usually block the fixed (permanently open) air wash intake using aluminum foil. Ideally one would adjust the air intake stop to allow it to close more fully, on my PE T5 fully closed is leaving the first 1/2" of a 2" circular opening still open.

 

[JRobyn]

Good that you are considering your glass and high ceilings. I did not give those characteristics adequate attention!

In my experience, many wood-burning devices over-produce to the degree that they are difficult to regulate well without having it 85 deg inside. IMHO, this is because stove and furnace designers are based in the frozen north where outdoor temps below zero are common.

So our new house has about 2500sqft of floor area. Thinking of the typical over-production, and our typical worst-case outdoor temps in the teens, I figured that my Charmaster Chalet wood furnace, specified as being good for up to 2500sqft would be way more than actually needed. But our great room is like yours; about 24ftx30ft, gobs of glass, and a vaulted ceiling from 18ft to 24ft. The Charmaster can just barely keep up. I have added 3 2500w electric baseboard heaters under the main large glass areas that helps a lot.

 

[Raspy]

As mentioned.

Consider putting a heating coil in the stove that ties in with the In floor system. For circulation use a 12 volt pump that can run off batteries in those cases power is out.

This had been tried many times, but for various reasons I don't think it's a good idea. Not much useful heat is actually gained from it. It must be able to withstand having no circulation with a hot fire during a power failure or pump failure. You can send scalding hot water to the radiant tubing repeatedly and weaken it. The heat exchanger takes up useful room in the stove and is always heavily coated with creosote because it runs much cooler than the fire.

It's just hard to mix water with fire in a wood stove and expect long term operation or practicality.

 

[Raspy]

Woodchuck,

Another thing you might consider is an outside air supply. Mine is simply a 5" single wall galvanized vent pipe run to the back of the stove from outside. My stove allows for a direct connection, but if your doesn't, just terminate it close to the stove intake. Then you have a definite cold air supply without having to draw a vacuum on the house and having cold air enter through a leak somewhere else, or starving the fire.

And the ceiling fan is very important.

I like to run single wall vent pipe up to almost the ceiling because so much of the output goes up the stack. Any air movement in the room really helps extract more heat from the stack.

 

[Rustyiron]

Woodchuck,

Another thing you might consider is an outside air supply. Then you have a definite cold air supply without having to draw a vacuum on the house and having cold air enter through a leak somewhere else, or starving the fire.

This is an excelent point considering your SIP's construction! Are you installing a HRV?

 

[JRobyn]

This had been tried many times, but for various reasons I don't think it's a good idea. Not much useful heat is actually gained from it. It must be able to withstand having no circulation with a hot fire during a power failure or pump failure. You can send scalding hot water to the radiant tubing repeatedly and weaken it. The heat exchanger takes up useful room in the stove and is always heavily coated with creosote because it runs much cooler than the fire.

It's just hard to mix water with fire in a wood stove and expect long term operation or practicality.

I know that the subject is wood STOVES and not wood furnaces, but my wood furnace has a "domestic hot water loop" in the upper part of the firebox where it doesn't interfere with loading, and the manufacturer's recommended installation is to run it through a "tempering tank", which consists of an old water heater right next to the furnace, plumbed such that the hot water loop thermosiphons through it continuously. This keeps the loop inside the firebox cooled, and levels out output water temperature swings quite well. Works great for domestic HW. Don't know how it might work for radiant tubing. The hottest discharge I have ever seen from the furnace into the tempering tank was about 180-185degF,

 

[WoodChuckDad]

This is an excelent point considering your SIP's construction! Are you installing a HRV?

As I understand it, the HRV is used with duct work systems. I plan to only have the radiant floor and mini-split type AC units with no heat pump function. I will have an outside air source for the Woodstove and for ventilation but haven't found anything that addresses the HRV issue.

 

[Egon]

I know that the subject is wood STOVES and not wood furnaces, but my wood furnace has a "domestic hot water loop" in the upper part of the firebox where it doesn't interfere with loading, and the manufacturer's recommended installation is to run it through a "tempering tank", which consists of an old water heater right next to the furnace, plumbed such that the hot water loop thermosiphons through it continuously. This keeps the loop inside the firebox cooled, and levels out output water temperature swings quite well. Works great for domestic HW. Don't know how it might work for radiant tubing. The hottest discharge I have ever seen from the furnace into the tempering tank was about 180-185degF,

Lots of ways to place the exchanger. It does not even have to be in the firebox. The tempering tank would be the logical way to set it up.

 

[Rustyiron]

As I understand it, the HRV is used with duct work systems. I plan to only have the radiant floor and mini-split type AC units with no heat pump function. I will have an outside air source for the Woodstove and for ventilation but haven't found anything that addresses the HRV issue.

You are right! "duh" moment for me. Crack a window if you need it:thumbsup: