EXPANSION VALVE -*
The expansion valve furnished with your refrigerator has been sized for maximum
coil efficiency. To adjust superheat, place a thermocouple under the expansion
valve bulb. Read the suction line pressure as near coil as possible. (If, at
the condensing unit, estimate suction line loss at 2 PSIG). Convert coil suction
pressure to temperature. The difference between coil temperature and the
thermocouple temperature is superheat. (Use average superheat when expansion
valve is hunting). Do not set superheat until cases have pulled down to operating
temperature and never open or close valve over l/Z turn between adjustments and
allow 10 minutes or more between adjustments. Superheat should be set to 6-8OF.
REFRIGERATION LINES
Refrigerant connections (suction & liquid) are stubbed underneath the case.
Cases multiplexed together must be field connected by running refrigerant
lines in the space under the case. The field installed suction lines must be
insulated to prevent condensation accumulation on the floor. See the section
on "Recommended Piping Practices" for additonal details on piping practices.
IMPORTANT A SEAL AROUND LINES AFTERCONNECTIONS ARE'MADE. KEEP DIRECT FLAME
FROM BOTTOM OF REFRIGERATOR, AS HEAT WILL DISINTEGRATE THE BOTTOM AND INSULATION.
USE A HEAT SHIELD WHEN WELDING NEAR THE BOTTOM OF THE CASES.
REFRIGERANT
R-12 expansion valves are standard. If other refrigerant is used, the order
must specify the expansion valve to be supplied.
*,HEAT EXCHANGER (S3J
only)
Heat exchangers are standard in these refrigerators. They aid to increase
operating efficiency and reduce frosting and flood-'back to compressor.
OPERATION
On single condensing unit systems, a thermostat should be used to control
temperatures. The thermostat bulb is mo[lnted on the rear baffle on S3.modeld and
'.in the discharge air on the S3J, On parallel units, temperature control can be .
provided by EPR valve and thermostat. Chart #2 shows approximate settings for .
merchandisers. Since many variables are present in each-installation, such as 'i
. store temperature, length of tubing runs, temperature desired in refrigerator, etc.,
'Chart #2 is only a guide for-the installer.
DEHYCRATION OF REFRIGERATION SYSTEMS
Please read'ca~~fully.befd~~'~l~~i~g'~~~t~m intd operation. After laying
. refrigerant lines, they should be blown out before making final connection at
fixture or condensing unit. Use dry nitrogen to prevent any foreign matter
being left in the lines. Keep pressure below 250 pounds. To prevent scaling
due to brazing, dry nitrogen should be allowed to flow through lines while
brazing operations are taking place.
. After the refrigeration system has been pressure-tested and proven leak-free,
it is recommended that the system be dehydrated with a vacuum pump to 100 microns
for the first two evacuations and 500 microns on the third. The triple evacuation
method requires evacuating the system three successive times and breaking each
vacuum with dry refrigerant. Allow the pressure to rise above atmospheric pressure.
Revised 11/23/81
9
4
LI -
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