Air Makeup Unit Technical Training Manual

Section 3

Air Pressure Switch Proving a Fan

Discharge of fan (Plus side of switch)

120VAC signal is sent to the air pressure switch. If the fan is not generating the correct amount of pressure, the 120VAC signal is not allowed to leave the switch. When the fan energizes, and the proper amount of air pressure is detected, 120VAC signal is allowed to leave the switch back to the control panel or other device.

Minus tube

Plus tube

Air Pressure Switch

Air Pressure Switch Electrical Symbol

Inlet of fan (Minus side of switch)

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