Unit Heaters
A unit heater is an independent, self-contained appliance designed to supply heat to a given space. It is frequently referred to as a space heater.
The typical unit heater consists of a heating element, a fan or propeller and motor, and a metal casing or enclosure. Unit heaters supply heat by forced convection using steam, hot water, gas, oil, or
electricity as the heat source. The air is drawn into the unit heater and forced over the heating surfaces by a propeller or a centrifugal fan before it is expelled on a horizontal or vertical air current (see Figure 2-83).
Horizontal heaters have a specially designed broad-blade fan and are used for horizontal discharge space and spot heating assignments. When equipped with louver fin diffusers, the air stream can be directed in an unlimited number of diffusion patterns. A typical horizontal pipe suspended unit heater is shown in Figure 2-84.
Forced-air unit heaters are small blower units that exhibit sev- eral times the capacity of a gravity circulation unit of the same size.