EMI WLHA - Manual (Page 32)

www.enviromaster.com WLCA/WLHA High Wall Evaporator 32
troUBLEsHootinG proCEdUrE Continued
optional Heat pump
with Electric Heat
Continued
EMI heat pump systems utilize a reversing
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 being the compressor and the
second 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
set-point 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 24
V compressor signal between “Y”
and “C”. Check to see that the amp draw
corresponds with the electric heat rating.
The following current values apply
when the unit is connected to a 230V power
supply. These values include indoor fan mo-
tor current. If the supply power is different,
this will affect the amp draw of the heater.
5kW = 22.3 amps, 4kW = 18 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
resetting limit switch located on the heater
end plate or on the heater assembly will
interrupt power to the heater should an over-
heat condition 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, one time fuse link will open
and the heater will remain off (to restart a
new fuse link is required).
Units With Condensation pumps
EMI Air Handlers are available with an
optional condensate pump. Condensate
pumps are recommended when it is not
possible to gravity drain the condensation
from the indoor unit. Depending on the
pump manufacture the maximum lift for the
pump will vary. Consult the pump instruc-
tions for the maximum lift for the particular
pump being used.
Condensation generated by the evapo-
rator will collect in the pumps’ reservoir.
When the water level is high enough, a float
switch will close and energize the pump
motor clearing the water from the reservoir.
Should for any reason the water exceed the
maximum preset level, a safety switch will
open, there by interrupting the (Y) signal to
the condenser. This will prevent the evapo-
rator from generating more condensation
and spilling out of the unit.