7.10 Low Pressure Control

FOR HVAC INSTALLER ONLY

If the electric ventilation damper fails to operate:

1.Check that the wiring is correct and that voltage is present at the damper motor.

2.Check for any obstruction inside the damper. If the electric ventilation damper fails to operate after performing these checks, it must be replaced.

7.10 Low Pressure Control

If the low side refrigerant pressure drops to 15 PSIG, the low- pressure control opens and shuts off the compressor and impeller fan. It is an automatically reset control. It will close when the refrigerant pressure rises to 35 PSIG. Its primary function is to prevent damage to the compressor if a leak develops in the refrigeration system. It may also open if the unit is A) installed in a cool area (below 50 F) or B) installed where it is below 40 F and then started. Under these conditions, the unit will restart within several minutes. Until the unit warms up, it may cycle several times.

7.11 Condensate Pump Kit

An optional condensate pump kit is available from the factory for use with the UA-150H. Condensate is automatically pumped to a remote location when the water level in the pump's reservoir rises to close the float switch.

The pump also contains a safety float switch. The white leads from this switch extend from beneath the pump cover. This switch should be installed in series with the field wire that connects the blue (#5) lead from the UA150H to the blue (#5) lead on the control panel.

If the pump fails, this switch opens the compressor control circuit and stops water production before the reservoir overflows. The UA- 150H will continue to ventilate or circulate air as normal, but will not dehumidify until this switch closes.

Electric Schematics of the UA-150H

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Ultra-Aire 150H Installer’s & Owner’s Manual

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Therma-Stor Products Group For Hvac Installer Only, Electric Schematics of the UA-150H, Low Pressure Control