19
7 Sealed Systems
7.1 Sealed System Installation
See Figure 7-1
All Grant VORTEX Eco boilers are
suitable for use with sealed systems
complying with the requirements of BS
EN 12828:2003, BS EN 12831:2003, BS
EN 14336:2004.
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 EN 13831:2007.
• Pressure gauge.
• Safety valve.
• Approved method for filling the
system.
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 in the Sealed
System kit).
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.
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 2767:1991.
One or more drain taps (to BS 2879)
must be used to allow the system to be
completely drained.
Figure 7-2: Boiler with sealed system kit
Figure 7-1: Sealed system
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.
!
NOTE
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