A Combined Solar Water
 and Space Heating System

(Extracted from article in ReNew magazine No. 80, pp 40-44, July/Sept 2002)

The primary objective of this solar heating system was to reduce to an absolute minimum the need for any other heat inputs to the house - the goal was 100% solar heating.

Three key principles - maximum insulation, maximum internal thermal mass, and maximum summertime-sheltered north-facing glass.

The energy captured from 36 sq. metres of solar collectors on north-facing roof is stored in a 3000 litre steel water storage cylinder, located on the south side of the house. An electric pump transfers the hot water to any or all of seven hydronic plastic pipe loops in the house floor slab. Surplus heat is even used to heat a courtyard greenhouse, and in the warmer months to heat  the 20,000 litre swimming pool!

On a sunny winter's day, the tank temperature continues to rise, while the pump takes water away from it. By 5pm the entire house slab is noticeably warm, with the air temperature around 21 C. So far each morning the temperature has not fallen below 17 C.

Applying home-made solder to join the copper riser tubing to the galvanised corrugated iron.
The north-facing roof has dimensions 15m x 3.3m. This entire roof surface is covered with 6mm toughened glass sheets, which I acquired cheaply as seconds. Under the glass-surfaced area are actually 3 separate solar heaters - the 36 m2 space heater, a smaller 6 m2 domestic water heater, and in the centre an insulated louvred skylight, which directs sunlight to the back of the house in winter, and can be closed at night retaining the winter heat and blocking out the heat in summer.
=> Manoeuvring the 3000 litre storage cylinder to its final position before boxing it in and insulating it.

A 90 watt electric pump transfers the captured solar energy into the house slab. It circulates about 0.75 litres of the cooler return line water per second and is needed for only a few hours per day.

A simpler system would be to do away with the storage tank and circulate the heated water directly to the floor coils or even wall-mounted radiators.

"I consider the work we have done in fabricating this home heating system to be less than the effort of gathering, cutting, splitting, stacking, carting, feeding and cleaning an indoor fireplace for the rest of our lives. Through scavenging and not including the cost of our own labour, the system cost around $3000."

"If you consider yourself fairly capable and want something special around the house, go forth and DIY."

John Hermans, 2002.

View the complete article - requires Acrobat reader (or right click to download the pdf document - 263 Kb).
(Available with permission of ReNew magazine.)

Alternative Technology Association

Back to Solar Space Heater Demonstration page.