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outputs energized. This may be accomplished by setting the
thermostat to cool with a setpoint substantially lower than
room temperature. This will provide 60 minutes of operation
at the nominal rating speed (interface board display "C4" or
"H4") before there is a speed change (to a higher speed).
If this speed change occurs before the charging process is
complete, turn the system off, then restart the process.
2 Ton
MoDEl
(-024K)
Factory Charge
188 oz
for 15 ft. line set
Additional Charge
16 oz
for 40 ft. line set
Additional Charge
39 oz
for 75 ft. line set
Additional Charge
57 oz
for 100 ft. line set
Table 4. refrigerant charge Quantities
alternate Procedure for charging Heat Pump in cooling
Mode (with outdoor temperatures above 60° F) Based on
Subcooling:
While charging based on weight is preferred, this method is
acceptable. Use this method when the outdoor temperature
is 60 ° F or higher to verify the correct charge in cooling
mode. The indoor temperature should be between 70 ° F
and 80° F.
1. Connect the gauge manifold to the liquid and vapor service
valves. See Figure 5 (page 10).
2. Start the system in cooling mode. Allow the system to run
15 minutes to stabilize.
3. Record the liquid refrigerant pressure in psig at the service
valve.
4. Record the liquid refrigerant line temperature in °F at the
service valve.
5. Using the temperature value recorded, determine the
corresponding liquid refrigerant pressure from the upper
curve (for cooling) in the charging chart. See Figure 6 (page
11).
6. If the pressure measured in step 3 is less than the required
liquid refrigerant pressure determined in step 5, then
refrigerant needs to be added.
7. If the pressure measured in step 3 is greater than the
required liquid refrigerant pressure determined in step 5,
then the system is over-charged.
8. Add or remove charge from the system depending on the
measurements recorded. Allow the system to stabilize for
15 minutes before taking the next readings.
alternate Procedure for charging Heat Pump in Heating
Mode (with outdoor temperatures below 60 °F) Based on
Subcooling:
Use this method when the outdoor temperature is 60° F or
lower to estimate the correct charge in heating mode. The
indoor temperature should be between 65° F and 75° F.
The preferred method of charging is by weighing in the
additional refrigerant required. If a charging scale is not
available, the correct charge can be estimated by this method.
Refrigerant can be stored in the receiver and accumulators
and result in an over-charged system. If it is necessary to use
6
3 Ton
4 Ton
5 Ton
(-036K)
(-048K)
(-060K)
184 oz
282 oz
282 oz
16 oz
18 oz
18 oz
43 oz
44 oz
44 oz
62 oz
63 oz
63 oz
this method, follow up service should be scheduled when
the temperature is above 60° F, and then charge should be
verified in cooling mode.
1. Connect the gauge manifold to the liquid service valve and
suction service port located at the left side of the access
panel above the liquid service valve. See Figure 5 (page
10).
2. Start the system in heating mode. Allow the system to run
15 minutes to stabilize.
3. Record the liquid refrigerant pressure in psig at the service
valve.
4. Record the liquid refrigerant line temperature in °F at the
service valve.
5. Using the temperature value recorded, determine the
corresponding liquid refrigerant pressure from the lower
curve (for heating) in the charging chart. See Figure 6 (page
11).
6. If the pressure measured in step 3 is less than the required
liquid refrigerant pressure determined in step 5, then
refrigerant needs to be added.
7. If the pressure measured in step 3 is greater than the
required liquid refrigerant pressure determined in step 5,
then the system is over-charged.
8. Add or remove charge from the system depending on the
measurements recorded. Allow the system to stabilize for
15 minutes before taking the next readings.
noTE: Small variations in charge will have a more significant
effect on liquid line pressure in heating mode compared to
cooling
SYSTEM oPEraTIon
Thermostat
The primary control for the overall heating and cooling system
is provided by the indoor thermostat. Any standard two-stage
heat pump capable thermostat will be sufficient for operation.
Refer to the manual for the thermostat selected or installed
for configuration and usage details.
run Sequence
Before the first start after power-up and between cycles there
will always be a five minute (re)start delay imposed. With a call
for heat pump heating or cooling and before the compressor
is turned on, the outdoor fan will run for one minute to assure
that the outdoor temperature measurement is close to that of
the ambient air. The compressor will then ramp up to a speed
selected by the capacity control scheme.
The 18 SEER heat pump is a true variable speed unit.Normally
the heat pump compressor will operate at one of 5 speeds in
cooling and 5 in heating, each predetermined for a balance
of optimum efficiency and capacity.The outdoor fan motor will
also operate at multiple speeds, following the compressor.
For either heating or cooling mode, the speeds used will
depend on several factors, including:
• Whether first or second stage operation is called for by the
thermostat (which must be two stage-capable),
• Outdoor ambient temperature.
• The length of time the equipment has been operating during
the current cycle
• The operating speed history, for both the current and the
previous operating cycles.
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