Mitsubishi Electric City Multi CMH-WM250V-A, Service Handbook

Page: 144 / 436

[5-3 Hydro Unit Control ]
BS_05_E chapter 5 -
25
5
Cont
rol
(2) Starting the defrost operation
 The 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.
1) Evaporating temperature (Te)
 The defrost cycle will not start if other outdoor units are in the defrost cycle or until a minimum of 10 minutes have passed
since the completion of the last defrost cycle.
 If 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 SW4(913) to ON.
 Even if the defrost-prohibit timer is set to 90 minutes, the actual defrost-prohibit time for the next defrost cycle is 50 minutes
if the last defrost cycle took 12 minutes.
 All units in the heating mode will simultaneously go into the defrost cycle in a system with multiple units. The units that are
not in operation may or may not go into the defrost cycle, depending on the cumulative operation time of their compressors.
(3) Defrost cycle
*The indoor unit fan will stop during defrost.
Condition 1 Condition 2 Condition 3
Outside temperature
(TH7)
-5ºC [23ºF] or above -5ºC [23ºF] or below
Cumulative compressor
operation time
50 minutes or more
90 minutes or more if the defrost prohibit timer is set to 90.
250 minutes or more
Evaporating tempera-
ture (Te)
The evaporating temperature
has stayed below the tempera-
ture in the table below (Note1)
for 3 minutes
(Te ≤ 1.1 × TH7 - 7.5) continued
for 3 minutes or [{1.5 + 0.02 x
(20+TH7)} > 63LS] continued
for 3 minutes
The evaporating temperature
has stayed below the tempera-
ture in the table below (Note1)
for 3 minutes
(E)M200 - 300 (E)M350 - 500
SW4 (915) OFF -13 ºC -11 ºC
SW4 (915) ON -8 ºC -8 ºC
Outdoor unit fan Stopped
SV1a ON
21S4a OFF
21S4b, 21S4c OFF
SV2 ON
SV9 ON
SV10,SV11 OFF (Closed)
SV14
*1
*1. Only the EM200 through 450 models have SV14 and SV15.
ON (Open)
SV15
*1
OFF (Open)
LEV1 0 pulses
*2
*2. This value may be greater than 0 pulse depending on the 63LS and TH4 status.
LEV2a 1500 pulses (M200–300), 3000 pulses (M350–500, EM200–500)
LEV2b 3000 pulses (M200–500, EM500), 41 pulses (EM200–450)
LEV2c 3000 pulses (M500, EM500)
LEV4 0 pulses
DIP SW 001-10
ON (Bypass defrost) OFF (Heat recovery defrost)
Hydro unit LEV1 41 3000
SV1 ON OFF
WP1 Normal control Command value 100%
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