Solar Radiant Heating

Radiant heating (namely radiant floor heating) is compatible with solar hot water systems, that is, you can integrate solar and radiant technologies. Solar radiant heating is relatively easy to implement.

The compatibility issue

Radiant heating systems involve supplying heat directly to the floor (or to wall panels, or ceiling) using hot water. In most cases radiant heating is located in the floor. Radiant floor heating is very efficient and highly prized for the comfort it provides. Radiant floor heating works by embedding special tubing in a concrete foundation or an equivalent slab. When the hot water/fluid flows through the tubing the thermal mass of the slab holds the heat and drives it slowly into the room. Radiant heating systems only require water temperatures around 100ºF/38ºC, which a good set of solar panels can provide in normal sunlight conditions.

The solar subsystem

A solar powered radiant heating system is basically a combination of two sub-systems: a common solar hot-water system and a common floor-radiant heating system.

The type of solar panels and the type of solar hot water system vary with climate. Tube solar panels are a good option due to their higher efficiency, but flat solar panels can also be used in moderate or hot climates.

As to the type of solar system (thermosyphon, drainback , glycol anti-freezing systems... ) to use, that depends mainly on climate considerations.

A backup gas system is also necessary (as it is always in typical solar water heating systems) to provide enough water to the system in bad weather conditions or to respond to peak demands.

A good solar installer should be able to size the system properly and to define its design and components.

The Radiant heating subsystem

The use of solar radiant heating doesn't require any particular modification in the radiant floor heating desing. Just bet on a sufficiently high thick slab (a 4-6 inch thick slab is advantageous).

Typically modern radiant systems use a PEX (cross-linked polyethylene ) network of lightweight, durable, plastic, with a ½ diameter, running in a “S” loop under the floor, which is fully compatible with solar powering.

Solar Radiant Heating Advantages and Disadvantages

Solar radiant heating is an eco-friendly and highly appreciated solution, with very low operating costs. But it demands a very high investment.

Prices starting at $10-$12 per square foot ($100 per m2) are common (small solar radiant heating projects will cost proportionally more). The efficiency of the insulation of the building and the climate (which determines the type of solar system) are very important in the final design of the system and its costs.