Defrost; Defrost Start Condition; Defrost Release Condition; Outputs During Defrost - Hitachi RAM-55QH5 Service Manual

DEFROST

Reversing valve defrost system is employed: it consists of balancing period
(1)

Defrost start condition

When all the following conditions are established defrost is executed:
1 Normal operation
2 Heat exchange temperature is within defrost range specified by outdoor temperature and heat exchange temperature.
3 Defrost inhibit period linked to outdoor temperature has passed.
(2)

Defrost release condition

If any one of the following conditions is established, defrost is released:
1 Heat exchange temperature returns (heat exchange temperarure ≥ DEFOFF).
2 Defrost max time of 12 minutes has elapsed.
Released by condition 1 during balancing period: When remaining balancing period has elapsed, returned to initial
condition (ASTUS=0).
Released by condition 1 or 2 during reversing cycle period: [TDF415] Shifted to balancing period.
(3)

Outputs during defrost

Indoor defrost request: Transmitted to all units being operated in heating mode.
Compressor : Balancing period for [TDF414] seconds
[TSKTM2] seconds
period until defrost MAX speed [DEFMAX] is reached
Electric expansion valve
Unit being stopped : [FULL CLOSE] 30 seconds after balancing period has passed
Unit being operated : [DFCTPS] 30 seconds before balancing period is finished
RAM-55QH5, RAM-65QH5 DEFROST TEMPERATURE
-20
above graph is showing the ideal value by micon program.
Accelerating by [DFSTEP]min
reversing cycle period
of rotation speed of compressor, opened by [DFSPPS] pulses and reaches MAX opening
degree [DEFSMX] when rotation speed of compressor reaches [DEFMAX].
DEFROST END
TEMPERATURE
-10
reversing cycle period
Starting of reversing cycle period by [SDRCT2] min
-1 /[TDFSPT] seconds in remaining reversing cycle
Balancing period for [TDF415] seconds
[PCLOSH$] 15 seconds before balancing period is finished
20
10
0
0
DEFROST
-10
TEMPERATURE
-20
OUTDOOR (˚C)
– 62 –
balancing period.
[FULL CLOSE] during
Synchronized with step-up
10
START
-1 for
20