Heating and Cooling Equipment Glossary

Power & Energy Services, Residential and Business: APS

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Evaporative Cooler
An evaporative cooler cools by adding moisture to the air. In low desert areas most people find they provide an acceptable level of comfort before July 1 and after September 15, most years. In higher elevations they may provide comfort year around.

You can tell you have an evaporative cooler if: there is a waterline that runs to the unit, a separate thermostat or simple on/off control, and is operated with the windows open.

Air Conditioner
An air conditioner is a device which cools the indoor air by removing heat and depositing it outside. It circulates indoor air and does not bring outside air into the home. A filter in the return air duct is required to keep the air conditioner clean and operating efficiently. You can tell you have an air conditioner if you have a separate unit for heating.

Window A/C units are also used to cool homes. They are generally not as efficient as central air conditioners, but are useful for cooling small spaces where central air is not practical. Window units are rated in BTU’s of cooling capacity. As a rough rule of thumb, 1,000 BTU will cool 40 to 50 square feet of space with few windows and well insulated. An 8,000 BTU window unit should cool 300 to 400 square feet of space.

Thermostat
Air conditioners are controlled by thermostats which act as switches. When the thermostat calls for cooling it turns the air conditioner on. When the thermostat is satisfied it turns the air conditioner off. Setting the thermostat to a lower temperature will not make it cool any faster.

A programmable thermostat can be set to automatically raise or lower the thermostat while you are away from home or sleeping. It can be a convenient way to help save on your heating and cooling bills.

Heat Pump
A heat pump is a device that acts as an air conditioner in the summer and as an electric furnace in the winter. Heat pumps look and function exactly like an air conditioner in the summer, and is one unit used for both heating and cooling. The cost to cool a home with a heat pump is the same as with an air conditioner of the same efficiency rating. In the winter heat pumps heat the home by "reversing" themselves and "pumping" warm air into the home.

Review the High SEER Air Conditioners / Heat Pump and Getting the Right Size Air Conditioner / Heat Pump brochures for additional information.

Resistance Heating
Resistance heating means electric heat. It is less expensive to install, but two to three times more expensive to operate than a heat pump. Resistance heat is good where heating is used occasionally, gas is expensive, or where a heat pump is not needed for cooling. Baseboard resistance heaters can be installed to heat only the portion of the home you want, saving money by not heating the entire home.

Radiant Heating
Radiant heating usually refers to systems such as floor radiant heating. Heating occurs through radiation heat transfer. Radiation heat transfer is concerned with the exchange of thermal radiation energy between two or more bodies. Thermal radiation is defined as electromagnetic radiation and arises as a result of a temperature difference between two bodies.
No medium need exist between the two bodies for heat transfer to take place. Rather, the intermediaries are photons which travel at the speed of light.

The heat transferred into or out of an object by thermal radiation is a function of several components. These include its surface reflectivity, surface color, surface area, temperature, and orientation to other objects.

Infrared Heating
Infrared heating systems refer to pieces of equipment or appliances that are placed inside the space to provide heating. Heating occurs through radiation heat transfer. Radiation heat transfer is concerned with the exchange of thermal radiation energy between two or more bodies. Thermal radiation is defined as electromagnetic radiation and arises as a result of a temperature difference between two bodies.

As with radiant heating, no medium need exist between the two bodies for heat transfer to take place. Rather, the intermediaries are photons which travel at the speed of light.

The heat transferred into or out of an object by thermal radiation is a function of several components. These include its surface reflectivity, surface color, surface area, temperature, and orientation to other objects.

Infrared heating equipment generally runs at hotter temperatures than radiant floor heaters.