Ceiling Radiant Cooling & Heating System

There are currently three different hydronic radiant cooling systems available. The panel system is the most common radiant system. The panels, usually aluminum, can be surface mounted or embedded on floors, walls or ceilings. The capillary tube system characteristics are small closely spaced tubes that are embedded in plastic, gypsum, or mounted on ceiling panels. The many tubes allow for better heat absorbing distribution and a thinner ceiling. And finally, the concrete core conditioning systems with tubes embedded in a concrete slab allows for peak load shifting because of its thermal storage capacity. This could be used also as a wall mass. In each of these systems, the water is mixed in a glycol solution and cooled by an air-to-water heat pump, a cooling tower, a ground-source heat pump, or even well water. Since the radiative surface is typically a whole floor or ceiling surface, the water can be as warm as 65.

Installation
The preferred installation is ceiling mounted, as this reduces air stratification, facilitates collection of condensate, and involves less structure. The piping network is tied into a heat transfer source such as a heat pump. The transfer medium can also cool the coil for an air handler to provide air movement.

Benefits/Costs
Due to the high heat capacity and density of water, thermal energy can be transported in water in pipes with little pump power, saving approximately 70 to 80% of fan power normally used to condition a building. This alone reduces the peak-power of the air-conditioning system by about 30 to 45%. There is no space conditioning equipment necessary on exterior walls, and the panel system can use the automatic sprinkler system piping in some multi-family dwellings. Radiant cooling panels with
Minimum fresh air supply is a draft and free system that also eliminates fan-coil and induction unit noise. Cooling is more evenly distributed, and drafts can be eliminated. There is less exfiltration of cooled air when doors or windows are opened.

Prices vary extensively depending on climate, existing conditions and system. According to distributors, amortization within 5-7 years is common.

Limitations
With professionally configured and installed units the system can be used in any climate, however because of the risk of condensation in very humid areas proper design and installation may be even more critical. These systems are most economical in areas like Arizona where the humidity is less than 15%. A forced air system, such as an air handler or dedicated fresh air system, may need to be incorporated to remove humidity and pollen. Some systems have a relatively slow system response. Once room surfaces reach a desired temperature, however, they tend to maintain that temperature with relatively little extra energy.

Code/Regulatory
A new and seldom-used technology, radiant cooling is not regulated in the codes like radiant heating.

Availability
Since radiant cooling systems are constructed of components from the radiant heating and air conditioning industries, components are widely available, but engineers experienced in residential radiant cooling design are not.