Solar Powered Radiant Heating Systems

Integrating solar heating into an existing radiant heat system has never been easier, more practical or less costly. Here we show some high-level drawings of common implementations of solar heating, but each installation will be slightly different so we have engineers available to assist the installer with the design process.

In the first drawing (right) we show a very simple topology of a conventional hydronic radiant heating system. There is a pre-existing boiler, pumps and controllers that circulate the heat transfer fluid consisting of hot water/glycol, and a network of existing radiators (shown as a single radiator in the diagram). The fluid is circulated in a closed loop with the fluid circulated back to the boiler for reheating.

This type of existing heating system is a perfect candidate for the integration of a solar heating system, which will allow the boiler to operate far less frequently, and depending on configuration, the boiler may not need to operate at all. If your building has an existing air duct system instead of a radiator/floor system, check out our solar space heating system.

Radiator – This will vary from application to application and can include a wide variety of types of mounted radiators or in-floor systems to radiate heat into the space where the heat is needed. Similar to the cooling system in your car, in a radiant heat system hot water is pumped into a radiator where the heat is then released into the surrounding area.

Boiler -  This is the existing unit that heats the water that is distributed to the radiator(s). It typically consists of an insulated water tank with a burner as the heat source. The burner could be powered by oil, gas, natural gas, or it  could be an electric heating element. The boiler could also consist of, or be assisted by, a tankless water heater.

Solar Heating Integrated w/ Radiant System

In the diagram above, we show a simplified topology of a solar powered hydronic radiant heating system. Notice that the existing system remains in place with some control and plumbing modifications.

The existing boiler is still available to operate when needed - for example during a period of extreme low outside temperatures or after extended periods of cloudiness. Solar heating is not typically designed as a replacement for the existing system although it can be, more typically the purpose of a solar heating system is to provide a large solar contribution that dramatically reduces the need for the conventional system to run. Remember that conventional heating systems are designed to provide sufficient heat on the absolute coldest days of the year, so a typical heating system will have much more capacity than is actually needed, 95% of the time.

We normally recommend installing enough solar capacity to operate the system at 75% of the existing systems rated capacity in order to achieve the highest cost benefit and ROI (Return on Investment).

For purposes of adding solar heat to a system, it really doesn’t matter if the system is a baseboard system or heated floor system.

Another Take On Solar Radiant Heating

Hydronics - This refers to any system that uses water or a water mixture as the heat transfer medium. Residential hydronic systems are used for heating, and less commonly, for cooling. Commercial hydronics include steam heating and absorption chillers (and heaters).

Solar Radiant Heating With A Tankless Heater (Trim Heater)

The above diagram shows a solar heating system where the boiler has been removed, and we see the addition of a high efficiency tankless heater. Next to solar, tankless water heaters are the most efficient form of water heating available, making them an ideal companion of a solar powered hydronic heating system. Above we see a simplified topology where a tankless heater is integrated into the solar heat system to provide temperature trim or backup, eliminating the need for a conventional boiler.

Tankless systems instantly heat the water directly without the need for maintaining the temperature in a boiler tank. Also called instantaneous or “demand” heaters, these units are much more efficient than typical boiler systems, in part because they only heat water if and when needed and waste no energy maintaining water temperature in the tank. They fire up aggressively and shut off as soon as their work is done. They also have a much smaller footprint, conserving valuable space because they require no tank.

In any situation that includes integrated solar radiant heating, using a tankless system to replace the boiler is a consideration that should not be overlooked.