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Community and Q&A

Wood stove with water jacket in a well insulated house

OdinRoll | Posted in Energy Efficiency and Durability on

I am building my house and want to include a wood stove with water jacket.
The house is well insulated, there is 30 cm of insulation in the walls.
The wood stove will be placed in the living room, which is about 70 m2 (including the kithcen), this floor is directly connected with 50m2 on the floor above. Which gives a total of about 250m3 of room to heat directly. In addition there is a basement and two small cottages that I would like to heat with the water. And the tap water as well.
What I foresee as a problem is that the house is to well insulated so that the living room will be sufficient heated long before the water heat storage tank has reached its needed temperature. 
A solution could be a wood stove with extreme low energy output directly to the room, mostly to water.
I have found a Termorossella that gives 3 kw to air and 10,5 to water. But this might not be enough??
Or maybe it is possible to insulate the oven so that it will not transfer so much to air??
Do you have any solutions to this?
Yours sincerely Odin

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  1. GBA Editor
    Martin Holladay | | #1

    This is a complicated issue. The short answer is that if you are using a wood stove with a water jacket for both space heating and domestic hot water, you can never be sure that you'll get the right ratio of heat for these two different functions.

    Another problem: operating a wood stove in a tight house can be quite tricky, since wood stoves need enough air for combustion. (I realize that you called your house "well insulated," but you never claimed it was tight.)

    Here are two links to relevant articles you might want to read:

    "Flatrock Passive: Firing Up the Heating System"

    "Flatrock Passive: A Winter Update"

  2. OdinRoll | | #2

    Thank you for your answer Martin
    My house is not air tight. I am using a vapor retarder. And plan to supply air directly to the oven.
    I originally planed to use a Walltherm oven, but they are not allowed in Norway because of local regulations. I have found a
    that gives 3 k'W to air and 10.5kW to water, approximately 1/4 to air. I would like to have a lesser amount of energy to air. The one described in your link, the Walltherm, gives according to the article 1/6 of its energy to air. Which sounds very good. But when I look up the Walltherm pages i only find the new Walltherm Vajolet which gives of 1/5 of its energy to air. An oven that gives as much as 5/6 of its energy to water might help me on my way to solve my heating situation. Do you know which model this was?
    Yours Odin :-)

    1. Trevor Lambert | | #3

      Without trying to make the house reasonably airtight, the insulation you're adding doesn't make much sense. I think the proper way to go about this is to get your heating demand as low as you can, then figure out the options for heating. It almost seems like you're planning the heating system, then figuring out how to reject some of that heat, either productively (hot water) or unproductively (though air leakage in the house).

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