11
Connections for 2 or more boilers.
1 CONN 5: Main power-supply cables. Connect each boiler to its supply live, neutral, and earth, as
described on p.10. The supplies to each boiler can be on different phases if using a 3-phase
supply. Safe isolation warning notices must be fitted to units where multiple phase supplies are
used.
2 CONN 1 pins 2 & 3: Control signal. Join all the boiler ‘R’ terminals on the control terminal block
together and then connect them to the switched live control signal to the programmer control
circuit. Connect all the boiler ‘N’ terminals on the control terminal block together and then to
neutral on the programmer control circuit.
3 CONN 1: Pump connections. The pump must be connected through a relay assembly to ensure
that the pump always operates if any one boiler is running. (section 14, p.27). Relay box 95970135
is required for a two boiler system and 95970136 is required for a 3 boiler system.
Check the main electrical power connections are tight. Support the back of the PCB behind the power
terminals when tightening the main power terminals. Loose connections can cause a fire and will invalidate
the warranty.
The control RUN signal is optically isolated from the main boiler supply to enable different phases to be
used between boilers. The control signal required to operate the boiler is 220V - 240V at a very low current,
typically 10mA.
WARNING: THIS APPLIANCE MUST BE EARTHED.
All exposed pipework must be earthed in accordance with IEE Regulations.
After installation, preliminary electrical checks i.e. short circuit, earth continuity, resistance to earth and
check for correct polarity etc. must be carried out.
Before connecting the electrical supply, ensure the system is full of water and set to the correct pressure
(sealed systems), check for leaks. It is essential that all the air is purged from the system. Only then can the
supply be switched on.
On completion of the work the installation must be tested to IEE Regulations and an NICEIC Inspection and
Completion Certificate must be issued.
Please take note of the installation information. If in doubt please contact your local supplier or Heatrae
Sadia Technical Team on 0344 871 1535, option 1.
FIGURE 7 : BOILER INTERNAL SCHEMATIC
N
E
L
CONN5
N
R E N L
CONN1
CONTROL
ELEMENT
MAIN SUPPLY
CONTROL DEMAND PUMP OUTPUT
