Mitsubishi Electric PUHY-RP200, Service Handbook

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[
VII
Control ]
- 98 -
HWE10130 GB
-9- Controlling the plate heat exchanger 2 (Solenoid valve (SV3))(Opens when ON)
ΠThe valve positions in different modes are summarized in the table below.
-10- Defrost Operation Control
(1) Starting the defrost operation
ΠThe defrost cycle will start when all of the three conditions (outside temperature, cumulative compressor operation time, and
pipe temperature) under <Condition 1>, <Condition 2>, or <Condition 3> are met.
ΠIf 10 minutes have passed since compressor startup or since the completion of a defrost cycle, a forced defrost cycle can be
started by setting DIP SW2-7 to ON.
ΠEven if the defrost-prohibit timer is set to 90 minutes (or 250 minutes for "Condition 3" to be met), the actual defrost-prohibit
time for the next defrost cycle is 50 minutes if the last defrost cycle took 12 minutes.
ΠAll units in the heating mode will simultaneously go into the defrost cycle in a system with multiple units. Units that are not in
operation will remain stopped.
(2) Defrost operation
Mode SV3
Cooling OFF
Refrigerant oil recovery in the cooling
mode with the compressor operated
at low frequency
OFF
Heating OFF
Defrost OFF
Refrigerant oil recovery in the heat-
ing mode with the compressor oper-
ated at low frequency
ON
When high pressure (63HS1) rises in
the heating mode
SV3 turns on if high pressure (63HS1) exceeds 2.98 MPa while the compressor is
operated at the minimum frequency.
Condition 1 Condition 2 Condition 3
Outside temper-
ature (TH7)
-5ºC [23ºF] or above -5ºC [23ºF] or below
Cumulative
compressor op-
eration time
50 minutes or more
90 minutes or more if the defrost prohibit timer is set to 90.
250 minutes or
more
Pipe tempera-
ture (TH3)
The pipe temperature has stayed at or be-
low -10ºC for three minutes or the 63LS
reading has stayed below the value ob-
tained from the formula "1.5 + 0.02 x TH7"
for three minutes.
The pipe temperature has stayed below the
value obtained from the formula "Outside
temperature (TH7) -5ºC" for three minutes,
or the 63LS reading has stayed below the
value obtained from the formula "1.5 + 0.02
x TH7" for three minutes.
The pipe tem-
perature has
stayed at or
below -10ºC
for three min-
utes.
Outdoor unit Compressor fre-
quency
Model Compressor frequency
RP200 model 60Hz
RP250 model 60Hz
RP300 model 65Hz
RP350 model 65Hz
Outdoor unit fan Stopped
SV1a,SV1b ON
SV3 OFF
21S4a OFF
LEV1 480 pulses
LEV2 1400 pulses
SLEV 480 pulses