Section 6: Sealed Systems
Page 18
All Grant Vecta boilers are suitable for use with sealed systems
complying with the requirements of BS EN 12828:2003, BS EN
12831:2003 ad BS EN 14336:2004.
The system must be provided with the following items:
•
Diaphragm expansion vessel complying with BS EN 13831:2007
•
Pressure gauge
•
Pressure relief (safety) valve
•
Approved method for filling the system
6.1.1 Expansion vessel
The expansion vessel can be fitted in either the return or flow pipework
in any of the recommended positions as shown in Figure 6-1. To
reduce the operating temperature of the expansion vessel, 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. If the
expansion vessel is connected via a flexible hose, care must be taken
to ensure that the hose is not twisted.
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.
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6 Sealed Systems
6.1.2 Pressure Gauge
The pressure gauge must have an operating range of 0 to 4 bar.
It must be located in an accessible place next to the filling loop for the
system.
6.1.3 Safety Valve
The safety valve (provided with the boiler) is set to operate at 2.5bar. It
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 damage to property.
6.1.4 Filling Loop
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.
The filling loop must be isolated and disconnected after filling the
system.
6.1.5 Heating System
The maximum ‘setpoint’ temperature for the central heating water is
75°C. Refer to Section 1.1.
An automatic air vent should be fitted to the highest point of the
system.
If thermostatic radiator valves are fitted to all radiators, a system by-
pass must be fitted. The by-pass must be an automatic type.
All fittings used in the system must be able to withstand pressures
2
1
3
4
5
6
7
9
10
11
Static head of system
8
6.1 Sealed System Requirements
1. Expansion vessel
2. Pressure gauge
3. Pressure relief valve
4. Tundish
5. Removable filling loop
6. Double check valve
7. Automatic air vent
8. HW/HTG zone valves
9. Thermostatic radiator valve
10. Automatic bypass
11. Drain point
Figure 6-1:
Sealed heating system components
