Multiplexing, Line Sizing, Oil Traps, Pressure Drop - Hussmann MBC Installation And Service Instructions Manual

Attach two sensing probes (either thermocouple or thermistor) to the evaporator. One
under the clamp holding the expansion valve bulb and the other securely taped to the
evaporator inlet line as close to the coil as practical.
Some "hunting" of the expansion valve is normal. The valve should be adjusted so that
during the hunting the greatest difference between the two probes is 3º-5ºF for remote
merchandisers . With this adjustment, during a portion of the hunting the temperature
difference between the probes will be less than 3ºF (at times as low as 0ºF). Make
adjustments of no more than one -half turn of the valve stem at a time and wait for at least
15 minutes before rechecking the probe temperature and making further adjustments.
Self-contained merchandiser should be adjusted using the same technique with a
temperature difference of 6º to 8ºF.
REFRIGERANT –
The correct type of refrigerant will be stamped on each merchandiser's serial plate
located inside the merchandiser.
Refrigerant Piping – (Remote Cases)
Connection Sizes
The refrigerant line connections are behind the rear close-off panel, underneath the
drain tub, on the left hand end of the merchandiser as viewed from the rear.
After connections have been made, seal this outlet thoroughly. Seal both inside and
outside. We recommend using an aerosol dispensed urethane type of insulation.
Multiplexing -
Piping of remoted merchandisers operating on the same refrigeration system may
be run from merchandiser to merchandiser through the end frame saddles provided for
this purpose
DO NOT RUN REFRIGERANT LINES THROUGH MERCHANDISERS THAT ARE
NOT ON THE SAME REFRIGERANT SYSTEM - as this may result in poor
refrigeration control and compressor failure.
Line Sizi ng –
Refrigerant line should be sized as shown on the refrigeration legend that is
furnished for the store (not furnished by Hussmann). If a legend has not been furnished,
refer to Hussmann Application Engineering Manual for guidance.
Liquid Line 1/4" OD
Suction Line 3/8" OD
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