2.27 BOILER WITH EXTERNAL CONTROLS
1. The boiler must be provided with a 4 minute pump overrun
period. Failure to do so may invalidate the boiler warranty.
2. It is preferable that any pump used to circulate water
through an individual boiler is controlled by the local boiler.
Either as a 230V 50Hz supply as shown, enabled by the
Volts Free Contacts e.g. MFR1 or controlled by the option
kit for 0-10V pump control. If not then a pump overrun
function MUST be provided by the controlling system.
3. The pump load and switch on surge current must be within
the limits of the output if it is powered directly from the Volts
Free Contact. The limits are as specied in the Electrical
Specication Table below.
A slave contactor may be used to power the pump where
needed.
4. If the switched live is provided without a Volts Free Contact
then this MUST be taken from the same phase as the
boiler mains supply, preferable through the same isolator.
Externalcontrolsviaswitchedlivedemand
BoilerPumpcontrolleddirectlyfromMFR1
I1 I2 I3 I4 I5 I6
123 1234 12 12 123456 1234
L N PE
SwitchedLive
/VoltsFree
Contact
MainsSupply ExternalControls BoilerPump
MFR3 MFR4
VoltsFreeContacts
NO PE C NO C NO
MainsVoltage/230V50Hz
C NO PE C
MFR1 MFR2
~ LN
230V50Hz
Auxiliary
FusedSpur
/Isolator
SL1 L SL2 L ~L N PE
MainsSupply Demandinputs
230V50Hz
Interlock
External Controls via Switched Live Demand
Boiler pump controlled directly from MFR1
continued............
Electrical Specications for External Connections
Voltage Load
Input - SL1, SL2 230V 50Hz 3kΩ min
Input - 0-10V 0 to 10V DC 5mA max
Sensor - Outside
Sensor - Header
Sensor - Room
Sensor - DHW Tank
5V DC
10kΩ @ 25ºC β(25/85)=3977
Output - MFR1..4 output
24 V DC to 230V 50Hz 1.0 A max at CosØ = 0.6
230V 50Hz Peak Surge 20A < 20ms
230V 50Hz Peak Transient 100A < 10uS
Output - Pump 0-10V output 0 to 10V DC 10mA max
Bus - OT1, OT2 OpenTherm V 4.0
Bus - VariCAN CAN Open, proprietary protocol
32
Installation & Servicing
SECTION 2 - INSTALLATION
INSTALLATION
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