STRATUS Multi-Deck Display Case
21
Example: R-404
+ 33 F Suction Temperature
+ 28 F Suction Pressure Converted to Temperature
= +5 F Superheat
+ 33 F Suction Temperature
Suction Pressure
66.7 PSIG
Expansion Valve and Superheat
CAUTION: During service of this equipment, precautions should be taken to prevent loss of refrigerant to the
atmosphere. Always install the expansion valve stem cap after making valve adjustments.
The expansion valve furnished with your case has been sized for maximum coil efficiency. To adjust superheat,
perform the following:
1. Place a thermocouple near the expansion valve bulb. Read the suction line pressure as near coil as possible.
If closest is at the condensing unit, estimate suction line loss at 2 PSIG.
2. Convert coil suction pressure to temperature. The difference between the coil temperature and the thermo
-
couple temperature at the expansion valve bulb is superheat. Use average superheat when expansion valve
is hunting.
3.
Do not set the superheat until cases have pulled down to operating temperature and never open or close
the valve over ¼ turn between adjustments and allow 10 minutes or more between adjustments.
4. Superheat should be set at 6-8°F.
5.
After the initial setting, the superheat should be rechecked when product is loaded in the case and at
design operating temperature.
Superheat Calculations