Dip Switch Setting; Automatic Switch To Backup Heat Source Operation - Mitsubishi Electric EHST20C-VM2C.UK Service Manual

6-7. DIP switch setting

Located on the FTC printed circuit board are 4 sets of small white switches
known as DIP switches. The DIP switch number is printed on the circuit board
next to the relevant switches. The word ON is printed on the circuit board and on
the DIP switch block itself. To move the switch you will need to use a pin or the
corner of a thin metal ruler or similar.
DIP switch settings are listed below in the table below.
Before changing any switch settings, ensure power supplies to indoor and out-
door units are isolated/powered off.
DIP switch Function
SW1 SW1-1 Boiler
SW1-2 Heat pump maximum outlet water temperature
SW1-3 DHW tank
SW1-4 Immersion heater
SW1-5 Booster heater
SW1-6 Booster heater function
SW1-7 Outdoor unit type
SW1-8 Wireless remote controller
SW2 SW2-1 Room thermostat1 input (IN1) logic change
SW2-2 Flow switch1 input (IN2) logic change
SW2-3 Booster heater capacity restriction
SW2-4

Automatic switch to backup heat source operation

SW2-5
(When outdoor unit stops by error)
SW2-6 Mixing tank
SW2-7 2-zone temperature control
SW2-8 Flow sensor
SW3 SW3-1 Room thermostat 2 input (IN6) logic change
SW3-2 Flow switch 2 input (IN3) logic change
SW3-3 Flow switch 3 input (IN7) logic change
SW3-4 Electric energy meter
SW3-5 Heating mode function *3
SW3-6 2-zone valve ON/OFF control
SW3-7 Heat exchanger for DHW
SW3-8 Heat meter
SW4 SW4-1
SW4-2
SW4-3
SW4-4 Indoor unit only operation (during installation work) *4 Inactive
SW4-5 Emergency mode (Heater only operation)
SW4-6 Emergency mode (Boiler operation)
SW5 SW5-1
SW5-2
SW5-3
SW5-4
SW5-5
SW5-6
SW5-7
SW5-8
Note: *1. When the cylinder unit is connected with a PUHZ-RP/SUHZ-SW outdoor unit of which maximum outlet water temperature is 55ºC, DIP SW1-2
must be changed to OFF.
*2. External output (OUT11) will be available. For safety reasons, this function is not available for certain errors. (In that case, system operation
must be stopped and only the water circulation pump keeps running.)
*3. This switch functions only when the cylinder unit is connected with a PUHZ-FRP outdoor unit. When another type of outdoor unit is con-
nected, the heating mode function is active regardless of the fact that this switch is ON or OFF.
*4. Space heating and DHW can be operated only in indoor unit, like an electric boiler. (Refer to "Indoor unit only operation" in page 44. )
*5. If emergency mode is no longer required, return the switch to OFF position.
*6. Active only when DIP SW3-6 is set to OFF.
Automatic switch to backup heat source operation
Back-up heat source operation (*1) will automatically run when the outdoor unit stops abnormally. To enable the function, switch DIP SW 2-5 to ON. During the back-
up operation, an error code(s) and the contact number will be displayed alternately. External output (OUT11) will be available.
To clear the fault(s), reset the power breakers on the indoor and outdoor units.
<Applicable error codes (*2)>
E6 to E9, ED, P6, P8, U1 to U8, UD, UE, UF, UL, UP
(*1) Prolonged running of the back-up operation may affect the life of the heat source.
(*2) For safety reasons, this function is not available for certain faults. (System operation must be stopped and only pump keeps running.)
OCH570
WITHOUT Boiler
55ºC
WITHOUT DHW tank
WITHOUT Immersion heater
WITHOUT Booster heater
For heating only
Split type
WITHOUT Wireless remote controller
Zone1 operation stop at thermostat short
Failure detection at short
Inactive
—
Inactive
WITHOUT Mixing tank
Inactive
WITHOUT Flow sensor
Zone2 operation stop at thermostat short
Failure detection at short
Failure detection at short
WITHOUT Electric energy meter
Inactive
Inactive
Coil in tank
WITHOUT Heat meter
—
—
—
Normal
Normal
—
—
EHST20C-*M*C*
EHST20D-*M*C*
EHPT20X-*M*C*
—
OFF
WITH Boiler
60ºC
WITH DHW tank
WITH Immersion heater
WITH Booster heater
For heating and DHW
Packaged type
WITH Wireless remote controller
Zone1 operation stop at thermostat open
Failure detection at open
Active
—
Active *2
WITH Mixing tank
Active *6
WITH Flow sensor
Zone2 operation stop at thermostat open
Failure detection at open
Failure detection at open
WITH Electric energy meter
Active
Active
External plate HEX
WITH Heat meter
—
—
—
Active
Emergency mode (Heater only operation)
Emergency mode (Boiler operation)
—
—
Capacity code
SW5-3 SW5-4 SW5-5 SW5-6 SW5-7
ON ON ON ON
ON OFF OFF ON
OFF OFF OFF OFF
—
16
Default settings:
ON
Indoor unit model
OFF
ON *1
ON
OFF: EH*T20*-*C
ON : EH*T20*-*HC*
OFF: EH*T20*-M*C*
ON : EH*T20*-*M 2/6/9*C
OFF: EH*T20*-M*C*
ON : EH*T20*-*M 2/6/9*C
OFF: EHST20*-*M**C*
ON : EHPT20X-*M**C*
OFF
OFF
OFF
OFF: Except
EH*T20*-VM2*C
ON : EH*T20*-VM2*C
— OFF
OFF
OFF
OFF
ON
OFF
OFF
OFF
OFF
ON
OFF
ON
OFF
— OFF
— OFF
— OFF
OFF
OFF *5
OFF *5
— OFF
— OFF
OFF
OFF
OFF
— OFF
SW5
SW4
SW3
SW2
SW1