Radiantec's energy efficient tubing was developed with
grant support from the United States Department of Energy.
Considerable effort went into the design of a radiant heat exchanger
tubing that had optimal characteristics of service life, energy
efficient heat transfer and minimal electrical requirements for
pumping. Flow through the tubing was optimized to be "slightly
turbulent". Laminar flow (which is very smooth) and fully turbulent
flow (which requires excessive pump work) are both to be avoided.
The amount of heat that a heat exchanger tubing puts out is
directly related to the surface area (size) and the thickness and
conductivity of the walls. Other factors such as the rate at which the
heat can then be carried away from the tube, are relevant as well.
"Workability" factors are very important to consider. The tubing
must not kink readily or require unusual skill or care during
Service life and performance should never be sacrificed for very
easy installation. Rubber radiant heat exchanger tubings are highly
Some degree of over design is often appropriate for safety and
service life. However, the design of heat exchanger tubing always
involves trade offs and gross over design in one area will usually
compromise another. Waterline products are engineered for pressures of
100 psi at temperatures of 180° F They may be grossly over
designed if a tubing will operate at 15 psi and 120° F.
Lower operating temperatures in a radiant heating system are
important for energy efficiency, safety, long service life and
compatibility with alternative energy. Energy efficient condensing
heating units operate particularly well at low temperatures.