Has anyone combined a Trombe wall with a heat recovery unit?
Robert Guthrie| Posted inGreen Building Techniqueson
I want to extend my farmhouse using passive heating and cooling and also orientating it for optimal solar hot water and electricity generation.
I’ve wanted to include a Trombe wall. The standard design uses adjustable vents to either provide heated air or induce cooler air.
It just occured to me that a more modern approach might be to use a heat recovery unit to capture the generated heat.
Do you know this would be preferable? Has it already been done?
regards
Bob Guthrie
Australia
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Replies
Bob,
An HRV is not used to capture heat from a room or space containing hot air.
An HRV is used to raise the temperature of cold ventilation air during the winter.
On a sunny day, the space behind the glazing of your Trombe wall will be warm. The easiest ways to use that heat for space heating is via natural convection (the stack effect, through passive vents) or by using a fan to direct air from the space behind the glazing to your home.
Robert,
Good air distribution though out the whole house is the key. I’ve sealed the cavity behind the trumbe wall, let open vents at the bottom and installed a fanned return duct to the air handler to mix that hot air for the whole house. There are many failures of trumbe walls in the southwest US, all due to limiting the radiated heat to one room or one area of the house.
Bob,
Armando is right about Trombe wall failures. Trombe walls do not age well. Old Trombe walls have problems with glazing tape, spiderwebs, moisture, dust, and failure of materials due to high temperatures.
If you want to take advantage of the heat available from south-facing glazing -- or, in the case of an Australian house like yours, north-facing glazing -- here's an idea: use windows.
My dilemma has always been between the “advantages” of the Trombe wall, and the resulting loss of view. I had not anticipated maintenance issues. I greatly appreciate everyone's advice – Windows it is!!
Bob