Long Lineset Instructions

Page 22
HOW TO CHARGE A UNIT USING SUBCOOLING
1. Indoor temperature must be between 70F and 80F.
2. Measure liquid line temperature with temperature
sensor.
3. Hook up gauges to liquid and suction lines.
4. Turn on unit (cooling mode if heat pump – high stage
if two stage compressor) and operate long enough for
pressure to stabilize (at least five minutes).
5. Read condensing temperature from gauge and read
liquid line temperature from the thermometer.
6. To achieve 10F subcooling, liquid line should be 10F
cooler than condensing temperature. The amount of
subcooling will vary with outdoor temperature.
Add refrigerant to make liquid line cooler.
NOTE — If system is grossly overcharged, liquid line will
get warmer as refrigerant is added.
NOTE — After checking charge, if suction pressure is
excessively low, do not add charge. Check filters, air
volume and check for restrictions in system (i.e., strainers,
driers, expansion valve, etc.).
Recover refrigerant to make liquid line warmer.
LOW AMBIENT CHARGING (BELOW 70F OUTDOOR
TEMPERATURE.)
Airflow will need to be restricted in order to boost liquid line
pressure above 240 psig for HCFC-22, or 400 psig for
HFC-410A.
In order to obtain proper results, it is important that you
block equal sections of the coil with cardboard, plastic
sheet or similar material. On formed (wrap around) coils,
the blockage should be applied totally covering the coil from
top to bottom and then extending from side to side.
OUTDOOR COIL SHOULD BE BLOCKED ON SIDE AT A
TIME WITH CARDBOARD OR PLASTIC SHEET UNTIL
PROPER TESTING PRESSURES ARE REACHED.
CARDBOARD OR PLASTIC
SHEET
Figure 18. Blocking Outdoor Coil
Table 11. Low Ambient Cooling Recommendations
Product Family
Low Ambient Operation
Without Low Ambient Kit
Installed
Low Ambient Operation with
Low Ambient Kit added and
field installed Freezestat
Low Ambient Operation with
Low Ambient Kit, field
supplied Outdoor Fan Speed
Control* and Freezestat
Added
Split System
Residential and
Commercial
RFC
Metering
A/C or
Heat
Pump
Down to 60ºF
Kits not available. Operation
below Down to 60ºF is not
recommended.
.....
Expansion
A/C Down to 50ºF Down to 30ºF Down to 0ºF
Heat
Pump
Down to 50ºF Down to 30ºF
Cooling Operation Below 30ºF
is not recommend.
* Requires ball bearing motor construction. Outdoor fan motor may have to be changed in some instances.