10-2
10.2 Freeze-proof
models
This section describes our freeze-proof models designed to protect the unit against freezing in winter.
The freeze-proof models come standard with the freeze-proof kit.
Note
A standard model can be modified to the freeze-proof model.
For further information, contact us.
Freeze-proof kit
c
Low-temperature sensor
*1
d
Cement heaters
*1, *3
16W/200-220V
e
Fixing brackets
*3
f
Fixing plate
g
Cross recessed head screw
h
Heat insulating materials
*2, *3
*1
Connect the low-temperature
sensor and the cement
heaters to the control board.
(
ĺ
see 2.1.4.)
*2
Sandwich the heat insulating
materials between the fixing
bracket and the cement
heater.
*3
For models with 5.5 kW or
higher output, these items are
provided at one place only.
(1) Operation cycle
The following cycle starts during the stop of both pumps if the low-temperature sensor detects a water
temperature below 3°C:
a) The heaters start to heat water up to10°C.
b) The No.1 pump starts to perform zero-discharge operation for 10 minutes, followed by another
10-minute zero-discharge operation of the No.2 pump.
c) If the water temperature does not reach 10°C in 30 minutes after the end of both pumps’
zero-discharge operations, the system repeats the above cycle.
Note
appears on the display of the operation panel during the
freeze-proofing cycle.
Use of water ends any ongoing freeze-proofing cycle and switches to normal
operation.
Fig. 10-2(b) Freeze-proof operation cycle
#1 pump
Heater ON
#2 pump
10 minutes
10 minutes
10 minutes
10 minutes
50 minutes
50 minutes
Cycle end
Cycle start
1 cycle
The low-temperature signal is
turned “ON” at 3°C or less, and
turned “OFF” at 10°C or more.
Note:
The figure shows an
example of a model with an
output of up to 3.7kW.
Fig. 10-2(a) Freeze-proof kit
Low-temperature signal
