Unit Heaters

Packaged heating-only units typically utilize electricity or natural gas as their primary source of energy. As discussed in a later section, electricity is the most expensive source of heat energy and should be avoided. Natural gas (or liquefied propane) provides a more economical source of heat when used in packaged unit heaters.

Fan-forced unit heaters can disperse heat over a much larger area than packaged air-conditioners. They can distribute heat either vertically or horizontally and respond rapidly to changes in heating requirements.

High temperature infrared radiant heaters utilize a gas flame to produce a high-temperature (over 500°F, 260°C) source of radiant energy. Although they do not respond rapidly to changes in heating requirements, they are essentially immune to massive intrusion of cold outside air. Because they warm room surfaces and physical objects in the space, thermal comfort returns within minutes of an influx of cold air.

HVAC systems may be central or distributed; all-air, all-water, or air-water (induction). Each system type has advantages and disadvantages, not the least important of which is its energy efficiency. An economic analysis should be conducted in selecting an HVAC system type and in evaluating changes in HVAC systems in response to energy concerns.

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