Table of Contents
Advertisement
CONTROL SETTINGS MEDIUM TEMPERATURE
Conventional Single Compressor:
Measure Discharge Air Temperature at the center of the case at the discharge
honeycomb.
A thermostat or other device with a 3–6 deg F (1.7–3.3 deg C) differential must
control the merchandiser temperature. It will be wired to control the compressor
motor contactor.
Standard Off Time defrost is time terminated. On outdoor units, the defrost timer
will control a liquid line solenoid beginning a defrost pump-down 4 minutes before
defrost.
The defrost frequency and lengths listed may require adjustment for specific store
conditions. Factors include:
• Store temperature and humidity
• Low head pressure
• Long refrigerant line runs
• Seasonal changes
• Merchandiser temperature lower than recommended
When practical, defrost when store is closed.
Low pressure control settings apply to outdoor condensing units where ambient
temperature does not fall below 0 deg F.
CONTROL SETTINGS LOW TEMPERATURE
Conventional Single Compressor:
Measure Discharge Air Temperature at the center of the case at the discharge
honeycomb.
A thermostat or other device with a 3–6 deg F (1.7–3.3 deg C) differential must
control the merchandiser temperature. It will be wired to control the compressor
motor contactor.
HUSSMANN CORPORATION • U.S. & CANADA 1-800-922-1919 • BRIDGETON, MO 63044-2483 • MEXICO 1-800-890-2900 • WWW.HUSSMANN.COM • PN 3181178_A
Standard Electric defrost is temperature terminated. The defrost termination
thermostats for all the merchandisers on one compressor are wired in series.
Failsafe must not control defrost cycle length, especially when less than 208v power
supply is used for defrost heaters or if frost build-up is heavy from shopping demands.
On outdoor units, the defrost timer will control a liquid line solenoid beginning a
defrost pump-down 4 minutes before defrost.
Optional Gas defrost is time terminated and has fan cycling thermostat. The defrost
frequency and lengths listed may require adjustment for specific store conditions.
Factors include:
• Store temperature and humidity
• Low head pressure
• Long refrigerant line runs
• Seasonal changes
• Merchandiser temperature lower than recommended
Defrost after store closes when practical. Low pressure control settings
are applicable to outdoor condensing units where ambient does not fall
below 0 deg F.
CONTROL SETTINGS MEDIUM TEMPERATURE
Parallel Compressor Rack:
Measure Discharge Air Temperature at the center of the case at the
discharge honeycomb.
Merchandiser temperature must be controlled by a mechanical or
electronic pressure regulator or thermostat that will be mounted on the rack.
2-7
Advertisement
Table of Contents
Troubleshooting
