Alto-Shaam QC-40 Operations Instructions download pdf (Page 9)

#8402 QC-40 INSTALLATION & MAINTENANCE MANUAL PG. 7

Table 2.4.1 CONTROL MODE OVERVIEW

Mode Operation Description

Auto Chill

Refrigeration is controlled only by the food probe(s). Refrigeration continues

until all food probes achieve chill setpoint temperature, whereupon the control

automatically enters HOLD Mode.

Timed Chill Refrigeration is controlled by chill time entered and the cabinet air sensor. While

chilling, the cabinet air temperature may become exces-sively cold prior to chill

time expiration. The cabinet air sensor will then cycle the refrigeration system

OFF and ON, at cabinet air temperatures of 15°F (-9°C) and 20°F (-7°C)

respectfully, until chill time expiration. The control automatically enters Hold

Mode upon chill time expiration.

Hold Refrigeration is controlled by the cabinet air sensor only.

Auto Defrost Only the evaporator coil defrost heaters are operational with a 20 minute time

limit. A coil mounted defrost heater terminator switch (thermal) limits the

coil temperature to 60°F (15°C) maximum until 20 minutes expire. Auto

Defrost occurs automatically after six (6) hours of continuous evaporator fan

operation. The six hour "count-up" is overridden in either Chill Mode.

Manual Defrost Can only be selected in the HOLD Mode. See Auto Defrost for operation.

Upon completion of a manual defrost, the Quickchiller

will not automatically default to the Hold Mode. Control mode selection is

required.

NOTE: For optimum performance, utilize Manual Defrost at the start and end of each service day

Table 2.4.2

EVAPORATOR FAN, DOOR HEATER & CONDENSING UNIT OPERATION

OPERATION SPECIFICS

Evaporator Controlled by door switch and evaporator coil mounted for terminator

switch (thermal).

Fan(s) OFF when door is opened.

OFF with coil temperature above 60°F (15°C).

ON with coil temperature below 30°F (-1°C).

Door Heater ON and OFF with evaporator fan(s).

Condensing Unit(s) Controlled by a low pressure switch (cut-out @ 2 PSIG, cut-in @ 18 PSIG).

Upon control mode satisfaction, the liquid line solenoid valve closes to

begin a low side pump-down with condensing unit shutoff at 2 PSIG.

Upon call for refrigeration, the liquid line solenoid valve opens which

increases low side pressure to condensing unit start at 18 PSIG. Refer to

Section 2.7, Shut-Down Procedure for additional details.

NOTE: The RTD sensor(s) mounted to the evaporator coil serves no controlling

purpose and is for displaying coil temperature for reference only.

2.0 — Control Set-Up and Operation

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Alto-Shaam QC-40 Operations Instructions Page 9