8) Pump Interlock - Mitsubishi Electric PWFY-P200VM-E-AU Data Book

(8) Pump interlock

The unit may be damaged if it is operated with no water circulating through the pipes.
Be sure to interlock unit operation and the water-circuit pump. Use the terminal blocks for interlocking TB142A (IN1) on
the unit.
[Fig. IV. 3. (8).1]
[Fig. IV. 3. (8).3]
Unit
TB141A
OUT1
TB142A
IN1
Operation ON signal
Terminal No. TB141A OUT1
Relay contacts output Rated voltage : L-N : 220
Output
When Dip switch 3-6 is OFF
The relay closes during reception of cooling or heating operation signal from the remote controller.
(Note : it is output even if the thermostat is OFF.)
Operation
When Dip switch 3-6 is ON
The relay closes during thermo-ON.
Use of PWFY unit with the water pump can cause a heat exchanger freeze depending on the ambient air temperature or the
operation status of other indoor units in the same refrigerant system. This problem has become preventable by connecting the
water pump to the external output (TB141A : OUT1) contact so that when thermistors detect low water temperature, the water
pump is actuated to prevent heat exchanger from freezing.
The freeze prevention control is not associated with DipSW3-6.
Set DipSW1-10 to ON to invalidate the control for cases where there is no risk of freeze.
Pump interlock
Terminal No. TB142A IN1
Input Level signal
If the circuit of TB142A IN1 is open, compressor operation is prohibited.
Operation
(9) Anti freeze mode (Dip SW4-4 ON)
Anti freeze mode is to prevent water pipe from freezing.
The Anti freeze mode can set the heating temperature range between 10ºC~45ºC enabling the unit to maintain low water
temperature to prevent water pipes from freezing.
[Fig. IV. 3. (8).2]
Control Box (field supply)
TM1
52P
TM1
Rated load : 0.6A
Operation signal
Pump interlock
Strainer
Example drawing for pump interlock
L N
220/230/240V
MCB
X
TM1 :
52P :
MP :
MCB :
*Remove the short circuit wire of IN1 when wiring to
TB142A.
*Decide TM1 time lag considering circuit water volume
52P
and pump specifi cation so that the PWFY unit start its
operation when the water is fully circulated.
MP
240V
- 55 -
Control Box
In broken lines are field
supply products.
Pump operation
Water Pump
: Relay
Timer relay (closes after elapsing the
set time when it is powerd, while opens
promptly when it is not powerd.)
Magnetic contactor for water pump
Water pump
Circuit breaker