Filling The Central Heating System - Dunkirk DCC-150 Installation, Operation & Maintenance Manual

7.

FILLING THE CENTRAL HEATING SYSTEM

The system design pressure (cold) should be set to 14-21 PSI (1.0 - 1.5 bar). This pressure is equivalent to the maximum static
head in bar+ 0.3 (14.5 psi = 1 bar = 10.2 metres of water). Filling of the system must be carried out in a manner approved by the
local Water Undertaking. The system may be filled as shown in the figure.
Drain taps must be used to allow the system to be completely drained.
The heating system should be thoroughly flushed before the boiler is connected and again after the first heating.
A
Pressure gauge
B Pressure relief valve
C Heating return connection
D Cold DHW inlet tap / system filling connection for DCB-125 model
E
Gas shutoff connection
F Boiler filling connection
G DHW outlet/ indirect storage tank connection for DCB-125 model
H Drain connection for condensate trap
I Heating flow connection
J Optional Indirect DHW connection
Note:
Both heating return and the cold water supply inlet contain service filters.
• The boiler is fitted with an automatic air vent positioned on the pump (see section 2.9: "BOILER SCHEMATIC"). The vent is
fitted with an adjustable sealing cap.
• Open the central heating flow and return valves (spindle flats in-line with valve - see section 3: "BOILER INFORMATION").
• Open the fill point valve on the filling system until water begins to flow. To aid venting, the boiler drain point may be open until
water flows out. Close the drain point as soon as water appears.
• In systems using radiators to remove the air - Vent each radiator in turn, starting with the lowest in the system.
• It is important that the pump is properly vented to avoid it running dry and damaging its bearings. Unscrew and remove the cap
from the centre of the pump. Using a suitable screwdriver rotate the exposed spindle about half a turn, then replace the cap.
• Check the operation of the heating pressure relief valve by pulling the lever on top of the valve upwards lifting the seat. This will
allow water to escape from the system - check that this is actually happening.
• Continue to fill the system until the pressure gauge indicates 21.7 psi / 1.5 bar. Close the fill point valve and check the system
for water soundness, rectifying where necessary. Water may be released from the system by manually operating the drain
point until the system design pressure is obtained. The system design pressure (cold) should be between 1.0 bar and 1.5 bar.
Refer to section: "SYSTEM VOLUME".
• Open the cold water supply inlet valve (see section 3: "BOILER INFORMATION" and section 7: "FILLING THE CENTRAL
HEATING SYSTEM"). Turn on all hot water taps and allow water to flow until no air is present. Turn off taps.
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