Chapter 5.1.2 - Radiant Panel Characteristics

Radiant heating panels are used in residential, commercial, institutional, and industrial
buildings. Each type of panel has found application in all types of buildings, although
certain applications are more likely candidates for each type of radiant panel. For
example, discrete-metal or framed-fiberglass modules are common for T-bar grid ceiling
heating, whereas hydronic tubing and electric cables and mats are used for floor
heating or warming panels. Gypsum panel ceilings with embedded or surface-affixed
resistance wire were commonly used in residential, all-electric homes in the 1960s.
Where low-intensity, high-temperature heating is required, gas-tube, electric quartz, or
filament heaters are used.

Radiant heat is fuel-neutral. A radiant heater is not defined by the energy input;
rather, it is defined by the predominant method of heat output. Most electric radiant
heaters are available in 120, 208, and 240 V, and for some types 277 and 480 V is
available. International use requires design for additional specific voltages including
100, 200, 220, and 347 if uniform wattage output is desired for standard sizes or models.
Hydronic radiant panels may receive heated fluid from almost any source
designed to heat water, including geothermal heat pumps, boilers, combination
potable water heaters, and alternate energy sources.

Radiant panels provide unique opportunities for the provision of thermal comfort
and conservation of energy. Occupants of radiantly heated buildings confirm comfort
satisfaction. State-of-the-art design programs graphically verify comfort conditions
through a thermal comfort signature. Based upon comparative comfort satisfaction,
you would expect that radiant systems would be very common. In fact, radiant heating,
although very popular, is far from challenging the dominant market share of traditional
forced-air systems.There are many explanations, but it is very hard for both
users and the radiant industry to fathom why everyone does not have one form or
another of radiant heating.

Occasional failure of metal, rubber, and plastic concealed conduit has had little
impact on hydronic radiant heating growth. Electric radiant heating growth was
hampered by the rapid escalation of electricity costs following the oil embargo and
concealed radiant ceiling failures due to a few publicized materials and installation
failures. However, failures are extremely rare when licensed contractors who specialize
in radiant installations install materials with prominent testing organization
marks and labels.

Air conditioning is now a standard feature in new homes throughout the United
States.This has led some contractors to front-load air-conditioning costs, while lowering
the heating cost, thus making it harder for someone selling only heating to
compete. But perhaps the biggest hindrance to growth is the lack of comparative system
information output availability from the design programs in common use.When
convection and radiant systems are compared as though both are convection systems,
the radiant advantages are not apparent. Design programs must incorporate
the performance characteristics unique to radiant systems in order to provide robust
comparative information.

The lesson to be learned is that designers need access to computer simulation
programs that factor mean radiant temperature (MRT) into dynamic heat transfer
analysis that is related to occupant thermal comfort. It is essential that codes and
standards be monitored for inclusion of radiant, as well as other, heating systems.
Finally, additional research is needed to more precisely define occupant health and
productivity relationships to heating and cooling system thermal comfort performance.
ASHRAE Standard 55-92, Thermal Environmental Conditions for Human
Occupancy, provides a means by which this process could proceed were the Standard
to become central to system design.

There are proven materials, components, and equipment listed or marked by leading
nonprofit testing organizations for all radiant designs and applications. There is
also a large pool of qualified installers, many who are members of the Radiant Panel
Association (RPA) and are listed in the RPA Internet directory.The benefits of radiant
heating and cooling merit the “learning curve” investment to develop the same
specification confidence that is enjoyed with convection systems.

Radiant heating panels are used in residential, commercial, institutional, and industrial
buildings. Each type of panel has found application in all types of buildings, although
certain applications are more likely candidates for each type of radiant panel. For
example, discrete-metal or framed-fiberglass modules are common for T-bar grid ceiling
heating, whereas hydronic tubing and electric cables and mats are used for floor
heating or warming panels. Gypsum panel ceilings with embedded or surface-affixed
resistance wire were commonly used in residential, all-electric homes in the 1960s.
Where low-intensity, high-temperature heating is required, gas-tube, electric quartz, or
filament heaters are used.

Radiant heat is fuel-neutral. A radiant heater is not defined by the energy input;
rather, it is defined by the predominant method of heat output. Most electric radiant
heaters are available in 120, 208, and 240 V, and for some types 277 and 480 V is
available. International use requires design for additional specific voltages including
100, 200, 220, and 347 if uniform wattage output is desired for standard sizes or models.
Hydronic radiant panels may receive heated fluid from almost any source
designed to heat water, including geothermal heat pumps, boilers, combination
potable water heaters, and alternate energy sources.

Radiant...
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