6
SEALED SYSTEM REQUIREMENTS
This arrangement is useful for large systems where
lead to pumping over with conventional feed and vent
arrangements.
1. The top of the automatic air vent must be below the
cold water level.
2. The static water level (cold) must be at least 200mm
shown. The vent connection MUST NOT be made
immediately off the top of the boiler as venting is
3. The maximum practical length of 22mm cold feed
pipe should be used in order to reduce the effective
volume of hot system water expanding into the feed/
expansion cistern to a minimum.
a. A non-adjustable preset lift pressure not exceeding 3bar
(45lb/in
2
).
b. A manual testing device.
c. Provision for connection of a discharge pipe.
The valve or discharge pipe should be positioned so
that the discharge of water or steam cannot create
a hazard to the occupants of the premises or cause
damage to electrical components and wiring.
3. Pressure Gauge
A pressure gauge covering at least the range 0-4 bar
(0-60 lb/in
2
preferably be connected at the same point as the
expansion vessel.
Notes.
a. The method of lling, relling, topping up or ushing
sealed primary hot water circuit from the mains
via a temporary hose connection is only allowed
if acceptable to the local water
authority.
b. When installing the lling device,
it must be connected as shown
to fully comply with the water
regulations. This may involve
the tting of an additional WRAS
approval isolator valve to the mains
supply.
1. General
a. The installation must comply with the
requirements of BS. 6798 and BS. 5449.
b. The installation should be designed to work with
o
C.
c. All components of the system, including the heat
exchanger of the indirect cylinder, must be suitable
for a working pressure of 3 bar (45lb/in
2
) and
temperature of 110
o
C. Care should be taken in
making all connections so that the risk of leakage
is minimised.
2. Safety Valve
A spring loaded safety valve complying with the
intervening valve or restriction. The valve should have
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