14
Thermostat connections
The Q4SE heat pump requires a 2-stage heat pump
thermostat that must operate in conjunction with installed
accessories. A 3-stage heat pump thermostat is required
if electric heat is added.
The low voltage wires must be properly connected to the
units low voltage terminal block. See Figure 10 (page 17).
See Table 1 for proper wire gauge and their recommended
lengths for typical thermostat connections.
imPoRTanT noTe: The thermostat should be
mounted about 5 feet above the floor on an inside
wall. Do noT install the thermostat on an outside
wall or any other location where its operation may
be adversely affected by radiant heat from fireplaces,
sunlight, or lighting fixtures, and convective heat from
warm air registers or electrical appliances. Refer to
the thermostat manufacturer’s instruction sheet for
detailed mounting and installation information.
Table 6. Thermostat wire gauge
Thermostat
wire gauge
Recommended T-Stat wire
length (unit to T-Stat)
2-Wire
(Heating)
5-Wire
(Heating/Cooling)
24
55
25
22
90
45
20
140
70
18
225
110
STaRT uP & aDJuSTmenTS
Pre-Start check list
√
Verify the unit is level and allows condensate to drain.
√
Verify the outdoor coil and top of the unit are free from
obstructions and debris, and all equipment access/
control panels are in place.
√
Verify that the duct work is sealed to prevent air leakage.
√
Verify that the line voltage power leads are securely
connected and the unit is properly grounded.
√
Verify that the low voltage wires are securely connected
to the correct leads on the low voltage terminal strip.
√
Verify that the outdoor fan turns freely.
√
Verify that the power supply branch circuit overcurrent
protection is sized properly.
√
Verify that the thermostat is wired correctly. The
thermostat function switch should be set to OFF and
the thermostat fan switch should be set to AUTO.
Start-up Procedure
Close all electrical disconnects to energize the system.
Air Circulation
Leave the thermostat system mode on OFF, and set the
fan mode to ON. Blower should run continuously. Check
the air delivery at the supply registers and adjust register
openings for balanced air distribution. Examine ductwork
for leaks or obstruction if insufficient air is detected. Set
the thermostat fan mode to AUTO. The blower should stop
running. See Figure 9 (page 16) for blower delay profile.
Short Cycle Protection
1. With the system operating in cooling mode, note the
temperature setting of the thermostat and gradually
raise the set-point temperature until the unit de-
energizes.
2. Immediately lower the set point temperature of the
thermostat to its original setting and verify that the
indoor blower is energized.
3. After approximately 5 minutes, verify the compressor
and fan energize and the temperature of the discharge
air is cooler than the room temperature.
System Cooling
1. Set the thermostat’s system mode to COOL and the
fan mode to AUTO. Gradually lower the thermostat
temperature setpoint below room temperature and
verify the outdoor unit and indoor blower energize.
2. Feel the air being circulated by the indoor blower
and verify that it is cooler than ambient temperature.
Listen for any unusual noises. If unusual sounds
occur, determine the source of the noise and correct
as necessary.
3. Allow the cooling system to operate for several minutes
and then set the temperature selector above room
temperature. Verify the fan and compressor cycle off
with the thermostat. noTe: The blower should also
stop unless fan switch is set to the ON position.
