FireBird Combi Range Installation Commissioning Servicing & User Instructions page 37

SYSTEM FILLING, TESTING AND MAKE-UP
Introduction
Mains cold water is supplied through the boiler pipework to two separate circuits operating at
different pressures.
Circuit One
This is the Radiator Heating System including boiler and primary tank which is filled from mains
supply via flex filling loop (Page 45) within boiler to a pressure determined from system static head,
expansion vessel size and system water volume.This flexible filling loop should be disconnected
when boiler and system are filled and checked, See diagrams below.
Circuit Two
This is the domestic cold water supply through the boiler plate heat exchanger via domestic hot
water pipework direct to hot taps. This works at full mains pressure or if this is excessive at a
reduced pressure controlled by a mains pressure reducing valve to a pressure acceptable to
householder and satisfactory for the correct operation of Combi Boiler System.This mains pressure
reducing valve is not supplied with boiler, but will be available from a local supply merchant.
System filling should take place slowly and can be done by either of the following methods:-
Manual Filling
The Firebird Combi 90 comes with this system built into the appliance. It consists of a flexible hose
connection with a butterfly shut off valve at each end and a double check valve assembly at boiler end. To
conform to requirements of BS 7074 Part I and local water Authority Bye Laws, the flexible hose should be
disconnected at one end when filling has been completed and checked. Two end caps are supplied and should
be fitted to disconnected ends as a safety precaution against inadvertent opening of ball valves.
Pressure gauge on Control Panel should be checked
occasionally when system is cold. Refill to initial fill
pressure if necessary. Should this be a frequent
occurrence, complete system should be checked for
leaks.
Automatic Filling
Automatic System filling may be made with a feed and make-up cistern connected through a double check
valve and stop valve assembly to the return side of the heating system as close to the boiler as is practicable.
This cistern should be located above the heating systems highest point to give a minimum static head of
300 mm between it (highest point) and cistern. The manual filling system fitted to boiler should then be
disconnected and connection points blanked off.
This system has the advantage of automatic water
make-up in the event of system pressure loss due to air
elimination and minor leaks. In any case control panel
pressure gauge should be occasionally checked.
Remember also to check air fill pressure of
Expansion Vessel when system is cold using
standard tyre gauge connected to Schrader
air valve on vessel.
NOTE: There shall be no direct connection to the mains, even with the use of
a non-return valve without the permission of Local Water Authority.
* It is recommended that an inhibitor be added at the time of final fill to
protect the System from corrosion. Ensure that this is carried out in
accordance with inhibitor manufacturers instructions. Installer should
ensure that inhibitor used is suitable and that it will have no adverse effect
on Expansion Vessels diaphragms or any other part or component of the
system.
Method A
Method B
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