34
Marvair Wall Mount Heat Pump I&O Manual
06/2023 Rev.7
3.8 Electrical Connections
WARNING - ELECTRICAL SHOCK HAZARD
Failure to follow safety warnings exactly could result in serious injury, death, and/
or property damage.
Turn off electrical power at fuse box or service panel BEFORE making any
electrical connections and ensure a proper ground connection is made before
connecting line voltage.
All electrical work must meet the requirements of local codes and ordinances.
Work should be done
only by qualified persons.
CAUTION
This Marvair Heat Pump may incorporate an internal crankcase heater for compressor
protection.
The crankcase heater must be energized for at least 24 hours prior to
starting the compressor.
High Voltage Wiring
The power supply should have the proper voltage, phase, and ampacity for the selected model.
1. Refer to the electrical data on the data sticker on the unit for field wiring requirements of the unit.
Size the incoming power supply lines and the fuse(s) or HACR breaker(s) according to requirements
described in the National Electric Code. Run the power conductors through the knockouts on the side
or back of the unit. Use appropriate conduit and strain reliefs.
CAUTION
Note: Power supply service must be within allowable range (+10% - 5%) of rated
voltage stamped on the unit rating plate. To operate nominal 230/208V unit at 208V,
change the transformer line tap from 240V to 208V following the instruction on wiring
label in unit.
2. Connect the wires to the input side of the internal breaker (L1 & L2 for single-phase units; L1, L2,
& L3 for three phase models).
CAUTION
CAUTION! This system contains components that require phasing for correct rotation.
Failure to observe rotation and correct on start-up will cause damage not covered
by the Marvair
®
Warranty.
3. Scroll compressors, like several other types of compressors, will only compress in one rotational
direction. The direction of rotation is not an issue with single-phase compressors since they will
always start and run in the proper direction. However, three phase compressors will rotate in either
direction depending upon phasing of power. Since there is a 50-50 chance of connecting power in
such a way as to cause rotation in the reverse direction, it is imperative to confirm that the compressor
is rotating in the proper direction at the initial field start-up of the system. Verification of proper
rotation is made by observing that the suction pressure drops and the discharge pressure rises when
the compressor is energized. An alternate method of verification for self contained system with small
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
