Mitsubishi Electric CAHV-R450YA-HPB Service Manual page 114

[ VII Control ]
Control Method
-12- Automatic operation of pump for freeze-up protection
1. Purpose
This is a function to protect the water circuit from freezing up in winter.
2. Pump wire connection
3. Natural freeze-up protection
The units will operate according to the dip switch SW5-1 on the control board as shown in the table below.
Dip switch settings
Control method
Details
HWE22020
Control
board
I/O Box
CN511
X13 X704 X703
CN513
3 2 1 7 6 5 4 3 2 1
71 70
TB5
No-voltage contact output
SW5-1 OFF
Natural freeze-up protection based
on both the outside temperature and
the water temperature
Pump start conditions "Outside temperature is within ±1 ºC
of 1 ºC" AND "Inlet water
temperature is within ±1 of 3 ºC"
Pump stop conditions "Outside temperature is more than
±1ºC of 3 ºC" AND "Inlet water
temperature is more than
±1ºC of 5 ºC"
M
MP
3~
51P
52P
X20
X21
52P
PL
pump error
F2
ELB2
L1 L2 L3 N
- 105 -
H20 H21
X20 X21
SW5-1 ON
Natural freeze-up protection based
on both the outside temperature and
the water temperature
Same as left.
Same as left.
GB