2.7: Unit Heaters

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Page ID: 18030

Aaron Lee
BC Campus

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13 Unit Heaters

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A BCcampus element has been excluded from this version of the text. You can view it online here: https://opentextbc.ca/basichvac/?p=57

Unit heaters are often installed at ceiling height or recessed into a wall, and consist of a heating element, a built in blower fan and louvers to direct the direction of heated airflow. They are small and compact in size, yet have a high capacity for heating a room or area.

If a single unit heater is to be installed, its heated airflow should be directed towards the area of highest ambient heat loss, such as a window or door, however care should be taken to make sure that no surface is heated beyond a safe level.

If multiple unit heaters are installed their air flow should be directed in a circular motion along the exposed outer walls.

Control of unit heaters is similar to that of baseboard heaters, in that there must be a temperature activated switch, either installed directly on the heater unit, or more effectively, in another part of the room. A built-in fan switch is also provided to allow the fan to circulate air during warm weather without energizing the heater elements.

Unit heaters are available anywhere from 2 kW to 60 kW, with units on the lower side, up to approximately 5 kW usually being single-phase AC and controlled by low-voltage thermostats and relays, while units rated above 5 kW are usually three-phase.