Solar Space Heating Systems: Air Forced Systems, Radiators and Radiant Floor

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Solar Space Heating Systems: Air Forced Systems, Radiators and Radiant Floor

For Solar Space Heating basics - collectors, location, technology, sizing, etc. - see:
Solar Air Space Heating

The simplest space heating system

The simplest solar space heating systems collect solar radiation and then transfer the heated air directly into the rooms…

They are economical systems typically based on unglazed air flat-plate collectors, mounted vertically on the exterior of a home’s south-facing wall.

This solution is also particularly common in commercial and industrial applications, namely those demanding outdoor ventilation (warehouses, hangars…)

Be cautious, anyway: this isn’t a good solution in many cases and climates. Since these systems don’t use storage equipment or activation/deactivation controllers, they may easily inject too much hot air into the house. And since they are used just for house space heating, in most climates they are useless most of the year.

This system should only be implemented in climates with long and cold winters, or as a circumscribed space heating solution, applied to solve problems of ventilation or seasonal coldness in a room...

Note:
Most of the solar heating systems are configured to provide both solar water heating and a part (40-80%) of the home space heating needs. That's often the most advantageous solution.

Solar space heating through forced air systems, radiators and in-slab heat

Solar space heating can be a simple and basic system based on solar heated air, directly pumped into the rooms by fans or other system.

But it most cases it is integrated with:

- the house radiators;
- the home forced air ventilation system
- in-slab heat solutions…

Integrating the solar collectors system with forced air ventilation

The solar space heating systems may use forced air ventilation, and ductwork.

This system can be directly based on solar heated air, but in many cases it uses a liquid medium. In this last case, the solar heated water in the storage tank is pumped into a coil, which will heat the indoor air in the forced air ventilation system, whenever needed and possible: the system uses sensors and a thermostat that calls for heat and allows the pumping whenever the temperature of the solar heated water is sufficiently high.

Integrating the system with home radiators

Solar heated water can be used with modern baseboard radiators located in the living spaces. Usually the solar heated water is circulated in series with a boiler; whenever the solar heated water temperature is high enough, it will substitute the boiler...

The system demands at least mid-temperatures collectors (flat-plate collectors reach easily the 160ºF/70ºC, and evacuated …) and demands also modern baseboard radiators, able to operate at temperatures below 140º-160ºF/ 60º-70ºC (which is common today).

Note:
Solar heated water systems can also be used with steam radiators. But since these type of radiators demand higher temperatures, the solar collectors should also produce higher temperatures. In other words: you should use concentrators and evacuated tubes solar collectors…

Integrating the system with in-slab heat

Solar heated water can be used with radiant floor solutions. The system demands, obviously, a liquid medium, and preferable liquid flat collectors.

In this solution, solar heated water is simply driven and pumped through distribution piping located in the home’s floor. Since the temperatures of the water have to be relatively low (80ºF/27ºC or less, in most cases) there is no technical difficulty in the implementation of the system.

In cases where solar energy is insufficient, it can be installed an auxiliary heat device, connected to the solar tank (or connected in series with the solar system's heated water).

See also, for Solar Space Heating basics (collectors, location, technology, sizing...): Solar Air Space Heating