Four-Pipe Unit
How It Works Four-Pipe Unit Two-Pipe Unit with Electric Heat Two-Pipe Unit

Advantages for the Building Owner
Advantages for the Contractor
Sequence of Operation

This unit has a bypass duct in which the hot water heating coil is located, and utilizes face and bypass damper control of cooling and valve control of heating.

When the room thermostat senses a drop in temperature during cooling, the face dampers close (interrupting cooling) and the bypass damper opens. In the "dead band" range of the room thermostat, neither cooling nor heating takes place. On a further drop in room temperature, the hot water valve opens to the hot water heating coil. (Hot water shutoff valves are shown in the closed position. Hot water risers are not shown.)

 Four-Pipe Unit - Cool Four-Pipe Unit - Heat


Top of Page  •  Site Map  •  ©2006, The Whalen Company