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7.4.
Flush and Fill Boiler.
7.4.1.
Flushing:
The primary Heating circuit must be flushed according to BS7593. The system must be flushed with
10% of mains PPM or lower to ensure there is no debris trapped in the heating system, which would be
detrimental to the lifespan of the boiler.
7.4.2.
Heating System Fill.
A WRAS approved filling loop must be used in such a way that it never becomes a permanent
connection between the mains water and the heating system. There is a fill point on the boiler called a
‘water replenishing valve’. A temporary connection can be made to this to fill the system or top up the
pressure. Alternatively, this can be left closed, and a traditional filling loop installed.
Proceed as below
7.4.2.1.
Open the isolation valves that you have fitted to the flow and return of the heating system near
the boiler.
7.4.2.2.
Turn the cap on the ‘automatic air vent’ (behind the pump in the boiler) to ensure its not
screwed down. It needs to be free moving.
7.4.2.3.
Connect the filling loop to the ‘water replenishing’ connection
7.4.2.4.
Open the replenishing valve and fill the system slowly checking for leaks on the connections as
you do. Fill until the pressure on the pressure gauge reads between 1 and 1.5bar, then close the
replenishing valve.
7.4.2.5.
Vent the air out of the system and repeat the stage above
7.4.2.6.
Check the system (including the inside of the boiler) for leaks. Please allow at least an hour of
normal operation to confirm all fittings are leak free.
7.4.3.
Hot Water System Fill:
7.4.3.1.
Open the isolating valve on the cold-water supply to the boiler
7.4.3.2.
Open all hot water taps, showers, etc one by one until all the air has been purged from the hot
water circuit.
7.4.3.3.
Ensure that there is no air in the system by running the hot water taps until no spluttering can
be seen or heard.
7.4.3.4.
NOTE: If any air remains in the system when the boiler is turned on the water heater may fail
prematurely.
