Sunday, May 19, 2013

Building a Solar Heated Well House

This is a very nice and well documented project on the Alt. Build Blog that covers building a freeze resistant well house.  The idea is to keep the well plumbing and tanks above freezing with a passive solar heating system.

The well house and Trombe wall solar heater.

The well house is built from dry stack concrete blocks that are insulated with rigid foam insulation on the outside and then stucco for the outer weather surface.

A Trombe wall solar collector covers most of the south face of the structure -- the south wall concrete blocks are used for the mass of the Trombe wall, and twinwall polycarbonate is used for the Trombe wall glazing.

The advantage of using a Trombe wall for this situation is that the wall absorbs heat when the sun is on it, and this stored heat is released over the night time period to keep the structure above freezing for the full day.  The mass of the other wall concrete block walls should also help in maintaining a more even temperature -- putting the insulation on the outside of the block allows the wall mass to be effective in regulating the temperature of the space.  The mass of the water in the tanks should also help to even out temperature variations.

Trombe wall opening surrounded by stucco walls.
The entire project is described in 9 blog entries covering the whole build in a great deal of detail.  To my eye, the overall design and details are well thought out and executed -- a really nice job.

For colder climates, some changes that might be considered -- 1) use thicker insulation to reduce the heat loss out the roof and walls (possibly polyiso), 2) add insulation under the floor to reduce heat loss to the ground.  For really challenging climates, you  could consider going to a drain back solar collector on the outside that heats water in a relatively large unvented water tank on the inside that stores heat.  The heat loss from the heat storage tank would then heat the well house so that it stays above freezing.  The tank insulation could be set at a level such that the tank loses heat at a rate that keeps the inside of the structure above freezing all day -- even with some cloudy days.   The drain back circulation pump could be something like a PV powered TopsFlo pump, so that no separate differential controller would be needed.  While the drain back solution is more complicated and more expensive than the Trombe wall, the advantage is that its about twice as efficient as the Trombe wall collector -- so, it may payoff for cold climates.

All the details on the solar heated well house here...

Lots of interesting article on the  Alt. Build Blog -- have a look.

For hundreds more solar space and water heating ideas and projects...

Inside the well house.


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