Emerson VH User Manual

The electric panel should be inspected for any loose electrical connections.

The control system is divided into four (4) separate circuits. Fuses located on the transformer/fuse 

board individually protect the control voltage circuits. If any of the fuses are blown, first eliminate 

shorts, then use spare fuses supplied with unit. Use only type and size of fuse specified for your unit.
The small isolation transformer on the main control board supplies 24 volts to the electronics. The 

transformer is internally protected. If the internal protector opens, the transformer/fuse board must 

be replaced. Also check the control voltage fuse on the main control board before replacing the trans-

former/fuse board.

For Deluxe units, the Fan Safety Switch is located in the low voltage compartment and consists of a 

diaphragm switch and interconnecting tubing to the blower scroll. The Fan Safety switch is wired 

directly to the control circuit to deactivate the unit and activate the alarm system if airflow is inter-

rupted.

The optional firestat is a bimetal operated sensing device with a Normally Closed switch. This device 

will shut down the entire unit when the inlet air temperature exceeds a preset point. It is connected 

between terminals 1 and 2 at plug P39.

The optional smoke detector power supply is located on the base of the upflow units, and at the top of 

downflow units. It is constantly sampling return air through a tube. No adjustments are required.

Liebert manufactures a variety of water-detection systems, including point, zone and cable systems. 

Follow the instructions supplied with your selected device for proper installation, adjustment and 

maintenance.

A connection point is provided for customer-supplied remote shutdown devices. Terminals 37 and 38 

on the terminal strip are jumpered when no remote shutdown device is installed. Refer to the unit’s 

electrical schematic and the unit’s installation manual.

Be sure that power to the unit is shut down before attempting to tighten any fittings or 

connections.

Do not use near flammable liquids or for flammable liquid detection.