14
The Heading Numbers refer to the Electrical Circuit Diagram
1. ELECTRICAL FILTER
This cleans the incoming mains supply voltage to the PCB
It is wired as follows: L2 Live In (Brown)
N4 Neutral In (Blue)
U1 Live Out (Grey)
3U Neutral Out (Grey)
= Earth to Chassis (Green & Yellow)
2. MAINS SUPPLY
This is provided via a 3 core flex to the electrical filter, fitted to a 3 amp fused supply on the
plug and must be earthed.
3. EARTH CONNECTIONS
Four earth connections must be connected to the following terminals:
Boiler Chassis
Gas Valve
Fan
Central Heating Pump.
The clock requires no earth.
4. FAN
The fan draws 55 watts and runs on 220/230v ac. It is operated by relay number 1 and fed
from J10 (blue & brown wires, non- polarised). It must be earthed at the fan and at the
PCB
5. CENTRAL HEATING CIRCULATION PUMP
The pump operates in both central heating and domestic hot water modes. Supply voltage
is 230V ac fed from J9 on the PCB (blue & brown). Always operate at number 3 speed.
If power is supplied to the boiler and the pump has not run for 24 hours the PCB will power
up the pump for 1 minute. In addition, should the temperature at the central heating
thermistor fall to 6 degrees Celsius, the pump will run until a temperature of 9 degrees
Celsius is achieved. This is classed as first stage frost protection. For further details on
pump overrun times see box charts on D.H.W. and C.H. service (page 26)
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