INSTALLATION INSTRUCTIONS
14
3.6 Sealed Water System
Safety valve: a safety valve complying with BS 6750 Part 1 must be fitted close to the boiler on the flow pipe by
means of a horizontal or vertically upward connection with no intervening valve or restrictions and should be
positioned to facilitate testing. The valve should be pre-set and non-adjustable to operate at a pressure of 3 bar. It
must be arranged to discharge any water or steam through a pipe to a safe outlet position.
Pressure Gauge: a pressure gauge of minimum range 0-4 bar with a fill pressure indicator must be fitted to the
system at the same point as the expansion vessel in an easily visible position.
Expansion Vessel: An expansion vessel complying with to BS 7470:1 (for GB) or I.S. 813 (for I.E.) must be fitted to
the system by means of a connection close to the inlet side of the circulating pump in accordance with the
manufacturers instructions, the connecting pipe being unrestricted and not less than 15mm (1/2 in) nominal size.
The volume of the vessel should be suitable for the system water content and the air charge pressure should not
be less than the system static head. Further details of sealed system design can be obtained from BS 5449:Part 1
and the British Gas publication ‘Specification for Domestic W. Central Heating systems’.
Filling Point: A filling point and an approved stop valve to BS 1010 must be fitted and the method used for filling the
system should be approved by the water regulations. For further details see BS 6798.
G
CD
HR
HF
GAUGE
PRESSURE
SAFETY
PUMP
CIRCULATING
FILLING POINT
AIR RELEASE
POINT
VESSEL
EXPANSION
VALVE
FLOW
22 mm (min.)
RETURN
LOCKSHIELD VALVE
DRAIN
BYPASS WITH
COCK
