21
7.1 Sealed System Installation
See Figure 7-1
All Grant VORTEx Pro boilers are
suitable for use with sealed systems
complying with the requirements of BS
5449.
The maximum temperature of the central
heating water is 75°C.
The system must be provided with the
following items:-
•
Diaphragm expansion vessel
complying with BS 4814.
•
Pressure gauge.
•
Safety valve.
•
Approved method for filling the system.
7
Sealed Systems
Sealed Systems
Ensure that the expansion vessel used
is of sufficient size for the system
volume. Refer to BS 7074:1:1989 or
The domestic Heating design Guide
for sizing the required vessel.
The expansion vessel can be fitted in
either the return or flow pipework in any
of the recommended positions as shown
in Figure 7-1. To reduce the operating
temperature of the expansion vessel
diaphragm, position it below the pipe
to which it is connected. The expansion
vessel may be positioned away from the
system, providing the connecting pipe is
not less than 13 mm diameter.
The pressure gauge should have an
operating range of 0 to 4 bar.
The safety valve, set to operate at 2.5
bar, should be fitted in the flow pipework
near to the boiler.
The pipework between the safety valve and
boiler must be unrestricted, i.e. no valves.
The safety valve should be connected
to a discharge pipe which will allow the
discharge to be seen, but cannot cause
injury to persons or property.
Provision should be made to replace
water lost from the system. This can be
done manually (where allowed by the local
water undertaking) using an approved filling
loop arrangement incorporating a double
check valve assembly (as supplied fitted
on System models).
An automatic air vent should be fitted to
the highest point of the system.
The expansion vessel charge pressure
should always be slightly greater than the
maximum static head of the system, in
bar, at the level of the vessel (1 bar = 10.2
metres of water). See Figure 7-2.
The system fill pressure (cold) should
be 0.2 - 0.3 bar greater than the vessel
charge pressure – giving typical system fill
pressures of approx 0.5 bar for a bungalow
and 1.0 bar for a two storey house. Refer
to the Domestic Heating Design Guide for
further information if required.
If thermostatic radiator valves are fitted to all
radiators, a system by-pass
must
be fitted.
The by-pass must be an automatic type.
Filling of the system must be carried out
in a manner approved by the local Water
Undertaking.
Where allowed, the system may be filled
via the filling loop supplied (the loop
arrangement includes a double check
valve assembly).
All fittings used in the system must be
able to withstand pressures up to 3 bar.
Radiator valves must comply with the
requirements of BS 2767(10):1972.
One or more drain taps (to BS 2879)
must be used to allow the system to be
completely drained.
The expansion vessel is connected via a
flexible hose to allow it to be moved to
gain access to the baffle cleaning cover.
When replacing the vessel, care should
be taken to ensure that the flexible
connecting hose is not twisted.
Figure 7-1:
Sealed system
Figure 7-2:
Sealed system boilers
If thermostatic radiator valves are
fitted, the system
must
incorporate an
adequate by-pass.
NOTE
!
