5
Self-Contained Spot Merchandiser
that stops the refrigeration cycle and energizes the defrost circuit to energize the defrost heater. The defrost cycle
is terminated either by a temperature sensor connected to the electronic controller or failsafe time returning the
merchandiser into refrigeration mode. A defrost heater safety limit thermostat (Klixon) is wired in series with the
defrost heater that opens if the temperature exceeds 70°F.
Expansion Valve
The expansion valve furnished with the merchandiser was selected to provide maximum coil operating efficiency.
The expansion valve superheat is preset at the factory. Should it be necessary to adjust the superheat, place a
thermocouple on the suction line near the expansion valve bulb using a plastic wire tie. Measure the suction line
pressure at the suction line service valve (Figure 2-3). Convert the suction line pressure measured at the suction line
service valve to saturated evaporator temperature using a refrigerant pressure-temperature conversion chart. The
difference between the thermocouple temperature and the saturated evaporator temperature is the superheat. (Use
average superheat when the expansion valve is hunting) Do not attempt to set the expansion valve superheat until
the merchandiser has reached steady state operating temperature. Never open or close the expansion valve more
than a 1/4 turn between adjustments and allow a minimum of 15 minutes or more between valve setting adjustments.
Superheat should be set between 6-8 °F.
Refrigerant Piping
The suction line piping size is 1/2" outside diameter and the liquid line piping size is 3/8” outside diameter. The liquid
line and suction line are connected to service valves on the base of the condensing unit. All normal service except
compressor replacement can be done without removing the condensing unit.
Liquid Line / Suction Line Heat Exchanger
A liquid line / suction line heat exchanger is standard on these merchandisers. It helps increase operating efficiency
and reduces possible flood-back to compressors.
Condensing Unit
This dual temperature merchandiser incorporates a Copeland condensing unit with a KALB-015E-CAV model
Copeland compressor. The condensing unit is equipped with a preset crankcase pressure regulator set at 30 psig to
protect the compressor from overload after defrost termination and when operating in medium temperature mode.
The merchandiser uses a condensate evaporating pan with an electric heater that is used to evaporate defrost drain
water into the air. The low wattage evaporation pan heater operates to evaporate defrost drain water between defrost
cycles whenever the pan fills with water.
Refrigerant
The refrigeration system contains 5 pounds of R-404A (HFC) refrigerant. If the unit should require recharging, the
system must be evacuated and re-charged with 5 pounds of R-404A refrigerant.
The refrigerant charge for this merchandiser is very critical. If the merchandiser should need to be recharged, an
accurate charging device must be used. Refrigerant should not be released into the atmosphere and must be
reclaimed if removed from the refrigeration system.
