Defrost Heater Control - Mitsubishi Heavy Industries SRK25ZJ-S Technical Manual

◆
Heating
Operating conditions: When the outdoor air temperature (TH2) is 4ºC or lower continues for 30 seconds while the
1)
Detail of operation: The outdoor fan is stepped up by 2 speed step at each 20 seconds. (Upper limit 8th speed)
2)
Reset conditions: When either of the following conditions is satisfied
3)
a) The outdoor air temperature (TH2) is 6ºC or higher.
b) The compressor command speed is 0 rps.
(q) Refrigeration cycle system protection
1) Starting conditions
a) When 5 minutes have elapsed after the compressor ON or the completion of the defrost control
b) Other than the defrost control
c) When, after meeting the conditions of a) and b) above, the compressor speed, indoor air temperature (Th1) and in-
door heat exchanger temperature (Th2) have met the conditions in the following table for 5 minutes:
Operation mode
Cooling
Heating
2) Contents of control
a) When the conditions of 1) above are met, the compressor stops.
b) Error stop occurs when the compressor has stopped 3 times within 60 minutes.
3) Resetting condition
When the compressor has been turned OFF

(13) Defrost heater control

(a) Starting conditions
When all of the following conditions 1) – 4) have been met for 1 minute continuously, with the compressor frequency at 0 rps
or higher:
1) Operation is in the heating mode.
Outdoor heat exchanger sensor(TH1) temperature is lower than - 2.0ºC.
2)
3) Outdoor air temperature sensor(TH2) temperature is lower than 0ºC.
4) Outdoor air temperature, at 0ºC: Difference between the outdoor air temperature and the outdoor heat exchanger sensor
Outdoor air temperature, higher than - 5ºC and lower than 0ºC: Difference between the outdoor air temperature and the
Outdoor air temperature, higher than - 10ºC and lower than - 5ºC: Difference between the outdoor air temperature and the
Outdoor air temperature, higher than - 15ºC and lower than - 10ºC: Difference between the outdoor air temperature and the
Outdoor air temperature, lower than - 15ºC: Difference between the outdoor air temperature and the outdoor heat ex-
(b) Releasing conditions
When one of the following conditions is met:
1) Compressor frequency becomes 0 rps.
2) When even one of the starting conditions of (a) is lost. (When continuing for 1 minute)
Notes (1) The heater is forced to turn off during defrost operation. When the defrosting operation is over and the outdoor fan is turned on, the heater is forced to
turn on for 5 minutes. If the outdoor fan is turned off, the heater is also turned off.
compressor command speed is other than 0 rps.
Compressor speed (N) Indoor air temperature (Th1)
50 N < = 10 Th1 40
50 N 0 Th1 40
< =
temperature is larger than 4ºC.
changer sensor temperature is larger than - 5ºC.
-
Indoor air temperature (Th1)/
Indoor heat exchanger temperature (Th2)
< = < =
< = < =
outdoor heat exchanger sensor temperature is larger than 2ºC.
outdoor heat exchanger sensor temperature is larger than 0ºC.
outdoor heat exchanger sensor temperature is larger than
- 5ºC.
68
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'10 • SRK-T-098
Th1 4<Th2 −
Th2<Th1+6