HVAC Electric Resistance Heating
Electric resistance heating elements commonly are used in heat pump systems, wall heaters, radiant wall or ceiling panels, and baseboard heaters. They are less frequently used as a heat source for central warm air or hot water systems. Such heating devices usually require little maintenance, but their operating costs should be carefully considered when planning the building rehabilitation .
Assess the condition of all electric resistance heating devices by activating them and inspecting as follows:
►Electric resistance heaters. Electric resistance heaters are used in warm air and hot water systems, and in heat pumps. They incorporate one or more heavy duty heating elements that are actuated by sequence relays on demand from the thermostat. The relays start each heating element at 30-second intervals, which eliminates surges on the electrical power system. In warm air and heat pump systems, electric heating elements are normally located in the furnace or heat pump enclosure, but they may be located anywhere in the ductwork as primary or secondary heating devices.
Inspect the condition of all electric resistance heaters, including their wiring and connections.
If possible, observe the start up of the heating elements. Their failure to heat up indicates either a burnt-out element or a malfunctioning relay.
►Electric wall heaters. These compact devices are often used as supplementary heating units or as sole heat sources in houses for which heating is only occasionally required.
They may have one or more electric heating elements, depending on their size, and should be inspected as described above. Wall heaters often have a small circulation fan; check its condition and operation and look for dirt build up on the fan blades and motor housing. Inspect all electrical wiring and connections.
►Radiant wall and ceiling panels. Electric heating panels that are embedded in wall or ceiling surfaces cannot be directly inspected, but all radiant surfaces should be examined for signs of surface or structural damage.
If the panels do not provide heat when the thermostat is activated, check the thermostat, circuit breaker, and all accessible wiring to determine the cause or have an electrical continuity test performed by an electrician.
►Baseboard heaters. Baseboard heater heating fins can be damaged and become clogged with dust. Remove heater covers and inspect for such problems.
Bent heating fins can often be restraightened by combing. The thermostat may be on an adjacent wall or in the unit itself.
Editor's note: This story is adapted from the U.S. Department of Housing and Urban Development's Residential Rehabilitation Inspection Guide, 2000.Click here for other stories in this series.
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