PIPework
Do not obstruct flue fitting with Pipework.
Connect pipework as shown below.
Automatic air vent
Pressure relief valve
CH flow
CH return
Filling loop valve / drain valve
Pressure switch
Stat pocket
5
5.2 systeMPaC CondensIng BoIler - Installer guIdelInes
sealed HeatIng CIrCuIt
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
at the rear of the electrical control panel. If a boiler
overheat condition arises the burner will stop and
remain inoperative until this thermostat reset button is
pressed.
Trapped Gully
Safety Pressure
Release Valve
(within Boiler)
* a pressure release valve to BS 6759 operating at 3 bar is
fitted. a discharge pipe of 15mm diameter is also fitted
to the discharge connection on the pressure release
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.
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 pressure gauge with a 0 to 4 bar range is fitted to the
boiler control panel. This indicates water pressure in the
boiler and system at time of reading. Pressure when
cold should be
1
/
2
bar minimum to 1.5 bar maximum.
This is known as Initial System Design Pressure (P
i
).
n.B. Initial system design Pressure (measured in bar)
equals static head of system (measured in bar) plus
0.3.
sealed HeatIng CIrCuIt
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
at the rear of the electrical control panel. If a boiler
overheat condition arises the burner will stop and remain
inoperative until this thermostat reset button is pressed.
When the system is cold and filled to initial fill pressure P
i
the
pointer on the pressure gauge should point to 1 bar.
The pressure gauge shown has two red zones marked on
it. The first is between 0 and
1
/
2
a bar. If the pointer falls into
this zone when the system and boiler are cold, this indicates
that the initial System Fill Pressure has dropped and this will
activate the pressure switch cutting off power supply to the
boiler. Refill system manually until indicated pressure rises
to 1 bar.
n.B. Insufficient pressure in the boiler will cause the
power supply to switch off.
* a 12 litre expansion vessel is fitted to the boiler, precharged
with air or nitrogen to 1 bar which allows a system static
head of 5 metres. If the static head is greater than this then
the air charge in the vessel must be increased to balance
the higher static head. the air charge should not exceed a
pressure of 1.5 bar.
If the static head is altered, then it is also necessary to alter
the air charge pressure to equal the static head (+ 0.3 bar).
This is necessary in order to keep the system water from
entering the expansion vessel until the system is being
heated and thus allow its maximum acceptance volume (V)
to be used only to accommodate the expansion of system
water during boiler operation.
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