23
Marvair Wall Mount Heat Pump I&O Manual
11/2021 New
critical refrigerant charges, where the installation of gauges may be objectionable, can be made by
monitoring the temperature of the refrigerant lines at the compressor. The temperature should rise
on the discharge line while the suction line temperature decreases. Reverse rotation also results in a
substantially reduced current draw when compared to tabulated values.
There is no negative impact on durability caused by operating three phase compressors in the reversed
direction for a short duration of time, usually defined as less than one hour. However, after several
minutes of operation the compressor's internal protector will trip. The compressor will then cycle on
the protector until the phasing is corrected. Reverse operation for longer than one hour may have a
negative impact on the bearings.
To change the rotation, turn off power to the unit and reverse L1 & L2 at the disconnect.
4. Install the ground wire on the ground lug.
5. Units designed to operate on 460v. have a step down transformer for 230v. motors.
Low Voltage Wiring
1. Pull the low voltage wiring from the Heat Pump to the thermostat / sub-base assembly. Use 18 gauge,
with at least 7-conductors, Class 2 thermostat wire.
2. Mount the sub-base on a level plane. Connect the thermostat wire to the unit terminal board and the
thermostat as shown in Figure 7.
3. If applicable, attach the thermostat assembly to the sub-base. Check the stage two heat anticipator
setting. For units with electric heat and thermostats with an adjustable heat anticipator, energize the
electric heat and measure the current on the lead attached to the W2 terminal. Adjust/set the heat
anticipator per the instructions provided with the thermostat.
Terminals 8 & 10 on the Marvair with economizer can be connected to a normally closed smoke alarm
or fire stat to cause equipment shutdown when the circuit is opened. (Remove factory jumper).
CAUTION
The internal transformer is not designed to power other external devices.
