A visit to any plumbing and heating trade show will give evidence to the rise in popularity
of radiant heat. Not only can it warm the home, it can melt ice off the sidewalk or driveway,
or warm seedbeds in a greenhouse. Many factors contribute to its application and promotion.
This series of articles will deal with hot water radiant.
Comfort is the prime factor. The human body uses the feet and head to dispose of excess
heat. Because of this, warming the floor is not only physically pleasing, but the room will
feel warmer than it actually is, allowing for lower temperature settings and fuel conservation.
The downside to radiant for fuel conservation is slow recovery. With lower water temperatures
in the tubing, setting the thermostat back at night or when the house is vacant for short
periods is not possible, unless one wants to live with the discomfort while the temperature
slowly rises. An alternative to this will be offered under the heading of "combination
radiant and ducted".
Radiant heat can be installed in the ceiling when no alternatives are available, but the
comfort factor and efficiency are compromised.
Aesthetics plays an important part in the installation. Baseboard radiators around the
perimeter of each room or free standing cast iron units are eliminated. with the piping
in the floor or ceiling, the decor is not affected.
With hot water as the median for radiant heat, domestic hot water can be produced by the
boiler or water heater, allowing one appliance to do double duty.
The advent of computerized boiler controls that sense indoor and outdoor temperatures
and adjust the operating temperature of the boiler to meet demand instead of maintaining
a constant high temperature setting increases the overall efficiency of the system. During
warm weather, the boiler maintains just enough temperature to satisfy domestic needs.
Radiant tubing comes in a variety of materials. Cpvc, polyethylene, pex (cross linked
polyethylene; and many types of pex as well) reinforced rubber, Polybutylene, and the original
Pex-al-pex and poly-al-poly describe tubing that is layered. A core of pex or polyethylene
is wrapped with aluminum then an outer layer of pex or polyethylene covers the aluminum.
The aluminum forms an oxygen barrier to prevent deterioration of the plastic, and helps
retain the shape of the tubing during installation. When bent into a curve to make return
loops, the aluminum stops the plastic from springing back.