SEQUENCE OF OPERATION
When power is turned on and thermostat fan switch is
set to ON and the cooling indicator is set to OFF, the
indoor fan motor is energized through the normally open
contact FR1 of the FR fan relay in about 30 seconds.
The outdoor unit is off.
When power is turned on and thermostat fan switch is
set to ON or AUTO and the cooling indicator to COOL
the indoor and outdoor units will start through the
normally open contacts FR1 and FR2 of the FR fan relay.
AUTO position on the thermostat will stop and start your
system when the temperature setting is satisfied. The ON
position on the thermostat will stop the outdoor unit only
when the temperature setting is satisfied and the indoor
unit will continue to run, recirculating indoor air.
The fan coil unit is equipped with a protective device
called an anti-frost control which will automatically stop
the outdoor unit (while the indoor unit continues to run)
if ice accumulates on the indoor unit evaporator coil
causing abnormal operating conditions. When the
accumulated ice has melted, the anti-frost control will
restart the outdoor unit.
If fan coil unit is equipped with an optional float switch,
the condensing unit will automatically shut down if the
drain pan is full of water (condensate) and not draining.
The fan coil unit will continue to operate. When the water
level in the drain pan drops, the system will continue
normal operation.
PRIOR TO START-UP
1. Check all electrical connections for tightness.
2. Check air filter has been installed in return air box or
filter box.
3. Remove all winter supply shut-offs and store them in a
safe place.
STEP 9: INITIAL SYSTEM START UP &
OPERATION
1. Place thermostat fan switch in ON position and cooling
indicator in OFF position. In about 30 seconds, indoor
unit blower will start.
2. Check blower operation for excess noise or vibration.
3. Check entire distribution system for leakage and apply
additional tape where necessary.
SECTION 3: START-UP & OPERATION
4. Check that system static pressure is within acceptable
limits (minimum 1.0" W.C. - maximum 1.5" W.C.). Static
readings must be taken in the plenum a minimum of 18"
(or after the tee on ESP-4860D systems) from the fan coil
unit, plenum tees or elbows but before any supply run.
5. Check that blower motor amp draw compares with
fan coil unit rating plate. Amp draw shown on plate is
the FLA of motor (not the actual running amps) and will
vary with the pressure and voltage.
6. Place the thermostat cooling indicator in COOL
position, which will start the outdoor unit. Let the system
run at least 30 minutes to stabilize operating conditions.
7. For outdoor unit start-up, follow manufacturer’s
instructions.
8. Check that temperature drop across evaporator coil
in the indoor unit is between 20°F to 28°F.
9. Verify that system refrigerant is correct by one of the
following methods listed in order of preference by
Spacepak.
A. Check the super heat leaving the evaporator coil
against the corresponding suction pressure from the
schrader fitting at the fan coil unit which can be accessed
through the service panel. Superheat value should be
between 9° and 12°F.
B. If a sight glass has been installed on the liquid line at
the air handler check for the presence of flashing.
CHARGING COOLING ONLY SYSTEMS
After start-up, allow the system to operate for approxi-
mately 30 minutes in order to establish stable operating
conditions. Check that the temperature drop across
the evaporator coil is 20°F to 30°F. Do not attempt to
adjust the charge at ambient temperatures below 65°F.
1. Check refrigerant charge is correct by checking the
super heat leaving the evaporator coil against the corre-
sponding suction pressure from the schrader fiting at the
fan coil unit, which can be accessed through the service
panel. Superheat value should be between 9° and 12°F. If
a sight glass has been installed on the liquid line at the air
handler check for the presence of flashing.
2. Determine superheat from Figure 3.1.
3. If the superheat is too high, add refrigerant gas to the
suction line service port. Watch pressure gauge and
thermometer for correct superheat.
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