How Solar Space Heating Systems Work

• Solar space heating system diagram 1: single tank
• Solar space heating system diagram 2: dual tank

A single solar water heating system can supply domestic hot water and supplement space heating.

Although it is not cost effective to provide most of your space heating with solar in our climate, it is possible to use a solar thermal system to assist space heating needs. This is because when you need the most heat is when the solar resource is the least.

If we were to greatly increase the size of the solar collector to provide for space heating needs then there would be too much heat to store in the summer. A heat diversion would be needed to get rid of the excess heat. In addition, for solar heating to supplement hydronic heating, the heating system must operate at a low temperature, with return (from the floor to the boiler) temperatures below 100 degrees. Many heating contractors set the temperatures high so that the floor will respond more quickly to adjustments in the thermostat or to heat loss. These higher temperatures also mean less efficient operation, and less usable input from the solar system. Hybrid solar hot water systems that provide both domestic hot water and space heating are complex and can be costly. When incorporated in new construction, the cost is mitigated somewhat.

So does WSW install such systems? Yes, provided a client has realistic expectations. Kelly's home has extra solar collectors to supplement space heating needs. However, he designed the radiant floor system to run at low temperatures and he and his family are willing to be patient for adjustments in temperature.

For more information about solar thermal space heating, please contact us.