109
[A04] Antifreeze operation (1)
When the outside temperature and inlet water temperature is low (approx. 20°C or lower) and the room load is large
(operation frequency ≥ rating), the freeze prevention control may be activated.
Excess air
inside pump
Secure water
circulation amount
Dirt clogging
inside water circuit
12 M or longer
water pipe to
a branch, or 5 or
less branches
Fit buffer tank and the
second pump
Set DN code setting
DN_6D2 = “0”
Check wiring construction
Ask repair of power supply
No
No
No
No
(inside strainer, etc.)
Flow rate
detected by flow sensor is
almost same as actual
value
Hydro unit
DN code setting
DN_6D2 = “0”
Backup
heater terminal has
AC 220-240 V
( ± 10%)
Start
Operation restart
Perform
air vent
Replace flow sensor
Yes
No
Yes
Yes
Yes
Yes
Replace backup heater unit
No
(Backup heater NG)
Backup
heater element
is conductive
Correct wiring
No
Wiring connection
is normal
Yes
Replace TC, TWO,
and TWI sensors
No
Replace flow sensor
No
TC, TWO, TWI
sensor characteristics
are correct
Yes
Yes
Yes
Short circuit piping
circulation flow shortage
Fit buffer tank and the
second pump
Total water amount in
the system is too little,
or water piping is too
short
Check water heat exchange control board
If defective, replace it
PC board
MCC-1753
MCC-1755
(Refer to Characteristic table on page 137)
To Next Page
Loading...
