A solar hydronic radiant floor is a type of solar thermal heating. Thermal heating is no new idea and dates back to the ancient Greeks and Romans. In essence, thermal radiant heating is achieved by pumping heated water through tubing that runs beneath the floor of a home or office. Floors inherently have a thermal mass and can store heat for extended periods of time and, because heat rises, slowly and steadily heat the home. Solar thermal heating is often not effective enough to fully heat a home but it supplements active heating and air conditioning systems and can reduce fuel consumption by up to 90 percent.
Specifically, a solar hydronic radiant floor system pumps heated water from a storage tank into piping that has been laid underneath the floor. In turn, an individual thermostat regulates the flow of water to each room. A solar hydronic floor system first pumps the heated water from solar collectors into a storage tank. Then the water from the tank is pumped through the radiant floor tubing and heats the house. This type of system uses a heat exchanger, usually made of copper, to transfer heat from the collector to the water in the storage tank. This works well in providing a large heat storage capacity and good control over floor temperature.
It is possible, within the confines of a solar hydronic radiant system, to pump water directly from the solar collectors through the tubing in the floor. However, this system creates difficulties for temperature control. It is necessary to carefully calculate the system’s collector area-to-storage mass ratio. To overestimate would result in not enough heat for the system to properly function. If the ratio is underestimated, then the system might overheat.
Solar hydronic radiant heating can cost several thousand dollars and it is usually significantly more expensive than a conventional heating system in initial costs. However, these costs may even out over time through money saved on fuel consumption and heating costs. You can discuss with your contractor about advantages and/or disadvantages of a solar heating system in your location. The price will fluctuate considerably depending on the size and type of house, and the amount of solar energy available.