WLCG/WLHG
High-Wall Air Handlers
• Installation, Operation and Maintenance Manual •
P/N 240008111, Rev. G [06/18/10]
39
output of the 24v transformer (located in the
air handler) to ensure that the control voltage
is present.
EMI heat pump systems utilize a revers-
ing valve is that is energized in the cooling
mode.
The reversing-valve signal is provided
•
through the orange (O) low volt wire of
the air handler or thermostat.
It should remain energized constantly
•
as long as the indoor unit or thermostat
remains in cooling mode.
To check for 24v reversing valve voltage,
•
at the outdoor unit, place a voltmeter
across the brown (C) and orange (O)
wires while in the cooling mode.
Heating
Heat pump units can accommodate two-stage
heating when an optional electric strip heater
is present along with a heat pump condenser.
The first stage is the compressor and the sec-
ond is electric heat.
The air handler or wall thermostat will cycle
the condenser through the yellow (Y) wire as
it does in cooling, however the reversing valve
will not be energized.
To check for a condenser signal, place the
indoor unit or wall thermostat in heating.
Next place the set-point temperature one
•
degree above room temperature to call the
first stage of heating.
Then, with a voltmeter, check for 24 volts
•
across the yellow (Y) and brown (C)
wires at the condenser.
The electric heat should be off at this
•
point. Select a setpoint temperature that
is more than two degrees above the room
temperature to call for the second stage
of heating.
The electric heat should energize along
•
with the 24v compressor signal between
Y and C.
Verify that the amp draw corresponds
•
with to the electric heat rating.
The following current values apply when the
unit is connected to a 230V power supply.
These values include indoor fan motor cur-
rent. If the supply power is different, this will
affect the amp draw of the heater.
5kw = 22.3 amps
3kw = 13.5 amps
Units with electric heat utilize a control relay
located on the circuit board in the control
box.
As a safety feature, an auto-reset limit switch
located on the heater assembly will interrupt
power to the heater should an over-heat con-
dition occur.
Each electric heat assembly is also equipped
with a one-time fuse link. Should electric heat
temperatures rise above the auto resetting
limit switch, a non-resetting, the one-time
fuse link will open and the heater will remain
off. To restart, a new fuse link is required.
Units with condensate pumps
EMI Air Handlers are available with an op-
tional condensate pump. Condensate pumps
are recommended when it is not possible to
gravity drain the condensate from the indoor
unit.
The maximum lift for the pumps will vary.
Consult the pump instructions for the maxi-
mum lift.
Condensate generated by the air handler will
collect in the pump’s reservoir.
When the water level is high enough a the
•
pump motor will energize clearing the
water from the reservoir.
Should the water exceed the maximum
•
preset level, a safety switch will open,
interrupting the (Y) signal to the con-
denser.
This will prevent the air handler from
•
generating more condensate.
Troubleshooting
(continued)
