Supplied By www.heating spares.co Tel. 0161 620 6677
9
220692C
9
SECTION
Water Systems (Sealed)
2
2888
Sealed Water Systems
The installation must comply with the
appropriate requirements of the current
issue of BS5449, BS6798, BS4814 and
BS7074 Part 1 and 2.
See the diagrammatic layout.
Safety Valve
A safety valve must be fitted to a sealed
system.
It shall be preset, non-adjustable with a
lift pressure of 3bar, incorporating
seating of a resilient material, a test
device and a connection for drain.
The drain from the safety valve must be
routed clear of any electrical fittings
and positioned so that any discharge can
be seen.
Expansion Vessel
A diaphragm type expansion vessel, conforming to the
current issue of BS4814 (see also BS7074 Part 1 and 2)
must be connected at a point close to the inlet side of the
circulating pump, see the diagrammatic layout, unless
laid down differently by the manufacturer.
The expansion vessel volume depends on the total water
system volume and the initial system design pressure.
For any system an accurate calculation of vessel size is
given in the current issue of BS7074 Part 1.
Example: For an initial system design pressure of
0.7bar, the minimum total vessel volume required is
0.063xTotal System volume.
Note. A higher initial design pressure requires a larger
volume expansion vessel.
Guidance on vessel sizing is also given in the current
issue of BS5449 and BS7074 Part 1.
The charge pressure must not be less than the static head
of the system, that is, the height of the highest point of
the system above the expansion vessel.
The water capacity of the boiler is given in the Data
Table.
BOILER
3 LITRES (0.66 gal)
MAKE-UP BOTTLE
(if required)
NON-
RETURN
VALVE
AUTO
AIR
VENT
FLOW
22mm (min)
BYPASS
WITH
LOCKSHIELD
VALVE
RETURN
DRAIN
COCK
SAFETY
VALVE
(Make-up
alternatives)
EXPANSION
VESSEL
PRESSURE
GAUGE
CIRCULATING
PUMP
FILLING POINT
AIR
RELEASE
POINT
HEATING
CIRCUIT