FireBird HEAT PAC 120/150, Installation Servicing & Operating Instructions, Page: 34 / 56

DOMESTIC HEATING
S
EALED
H
EATING
C
IRCUIT
The system must comply with BS 7074 Part 1 and BS 5449 Part 1 with a maximum water
temperature of 80˚C.
* A manual reset overheat limit thermostat is located next to the temperature control dial on the
electrical control panel (see page 10). If a boiler overheat condition arises the burner will stop and
remain inoperative until this thermostat reset button is depressed.
* A pressure relief valve to BS 6759
operating at 3 bar (45 lb/in
2
) is fitted.
A discharge pipe of 15 mm diameter is
also fitted to the discharge connection
on the pressure relief valve. During
installation an extension pipe should
be fitted to this, leading, to outside the
building. The pipe should be as short
as possible and may need a tundish
fitted in a protected position within the
building.
Alternatively, if acceptable, it may
discharge within building. In this case
the discharge pipe
outlet end , should
terminate within 100 mm above inside
floor level, and be in a visible and
accessible position. No tundish is
necessary in this position and
householder should be advised that this discharge end should always remain open. In every case it
should be directed downwards away from any electrical components or where it could cause a
hazard to the user/occupier. See diagram above.
Note:- Water must not discharge above an entrance, window or where public have
access. The installer must be aware that the discharge may be boiling water.
* A drain cock must be fitted at the lowest points in the system to enable draining as necessary.
A drain cock is already fitted at the bottom of the boiler heat store to enable draining of boiler and
tank unit only. All pipes connected to boiler should have shut off valves fitted to facilitate this.
* A Pressure gauge, having range 0 to 6 bar is fitted to boiler control panel. This indicates water
pressure in boiler and system at time of reading.
Pressure when cold should be 1 bar
minimum to 1.5 bar maximum. This is known as Initial System Design Pressure (Pi).
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