Ecohome is in the process of building our next demonstration house, and to do so we have partnered with a company that manufactures frost-protected shallow foundations (slab-on-grade) that are heated with air rather than liquid. There are many advantages to air-heated radiant floors over hydronic radiant floors, but none greater than the ability to inject solar-heated air into the thermal battery which is the concrete slab floor.
Solar air-heaters are a growing trend online, with one notable shortfall – the heat that is generated is difficult to store. Many people take advantage of the relatively simple and affordable nature of air-heated panels (compared to photovoltaic panels) to harness the energy of the sun to heat garages and workshops, but solar air-heating has yet to be a viable and reliable option for well-balanced home heating. Until now ….
When looking for a heat-storage solution that would allow us to incorporate solar-air panels into our design in a sensible way, we approached Legalett, a manufacturer of slab-on-grade form kits and air-heated floors, to see if solar panels could feed air directly into their existing in-floor duct work. They welcomed the challenge and engineered the system that will be the main heat source of our demo house.
Legalett's existing floor-heating system consists of a closed-loop network of 4-inch tubes running through the concrete with a heater box imbedded directly in the floor. In this case, added to that system are 6-inch tubes (seen below) that will feed air to solar panels on the south wall of the house. Air heated by those solar panels will be fed into the floor heating system, which will reduce the demand on the heater coil.
While the main function is to provide solar heat in the winter, the panels will generate domestic hot water when heating is not required. This serves to protect the panels from damage that can occur due to overheating in summer.
In the springtime, our pre-fabricated house with dense-packed cellulose walls will be delivered and installed on the slab. Below is a short video of the slab construction, stay tuned for more on the house that will be seated on it!