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6
3.6
WATER CIRCULATION
Detailed recommendations are given in BS 5449
Part 1 and BS 6798. The following notes are for
general guidance only.
3.6.1
PIPEWORK
It is recommended that copper tubing to BS 2871
Part 1 is used in conjunction with soldered
capillary joints.
Where possible pipes should have a gradient to
ensure air is carried naturally to air release points
and that water flows naturally to drain cocks.
Except where providing useful heat, pipes should
be insulated to avoid heat loss and in particular
to avoid the possibility of freezing. Particular
attention should be paid to pipes passing through
ventilated areas such as under floors, loft space,
and void areas.
3.6.2
AUTOMATIC BY-PASS
The appliance has a built-in automatic by-pass,
consequently there is no requirement for an
external by-pass, however the design of the
system should be such that it prevents boiler
‘cycling’.
3.6.3
DRAIN COCKS
These must be located in accessible positions to
facilitate draining of the appliance and all water
pipes connected to the appliance. The drain cocks
must be manufactured in accordance with BS
2879.
3.6.4
AIR RELEASE POINTS
These must be positioned at the highest points
in the system where air is likely to be trapped.
They should be used to expel trapped air and
allow complete filling of the system.
3.6.5
EXPANSION VESSEL
The appliance has an integral expansion vessel
to accommodate the increased volume of water
when the system is heated. It can accept up to 8
litres (25/29) or 10 litres (35) of expansion from
within the system, generally this is sufficient,
however if the system has an unusually high
water content, it may be necessary to provide
additional expansion capacity (see 6.19).
3.6.6
FILLING POINT
A method for initial filling of the system and
replacing water lost during servicing etc. has been
provided. This method of filling complies with the
current Water Supply (Water Fittings) Regulations
1999 and Water Bylaws 2000 (Scotland).
3.6.7
LOW PRESSURE SEALED SYSTEM
An alternative method of filling the system would
be from an independent make-up vessel or tank
mounted in a position at least 1 metre above the
highest point in the system and at least 5 metres
above the boiler (see fig. 5).
The cold feed from the make-up vessel or tank
must be fitted with an approved non-return valve
and stopcock for isolation purposes. The feed pipe
should be connected to the return pipe as close
to the boiler as possible.
3.6.8
FREQUENT FILLING
Frequent filling or venting of the system may be
indicative of a leak. Care should be taken during
the installation of the appliance to ensure all
aspects of the system are capable of withstanding
pressures up to at least 3 bar.
3.7
ELECTRICAL SUPPLY
The appliance is supplied for operation on 230V
@ 50Hz electrical supply; it must be protected
with a 3-amp fuse. The method of connection to
the mains electricity supply must allow for
complete isolation from the supply. The preferred
method is by using a double-pole switch with a
contact separation of at least 3mm. The switch
must only supply the appliance and its
corresponding controls, i.e. time clock, room
thermostat, etc. Alternatively an un-switched
shuttered socket with a fused 3-pin plug both
complying with BS 1363 is acceptable.
3.8
SHOWERS
If the appliance is intended for use with a shower,
the shower must be thermostatically controlled
and be suitable for use with a combination boiler.
3.9
MOUNTING ON A COMBUSTIBLE SURFACE
If the appliance is to be fitted on a wall of com-
bustible material, a sheet of fireproof material
must protect the wall.
Fig. 5
Make-up vessel
or tank
Automatic
air-vent
Non-return
valve
Stopcock
5.0 metres minimum
Heating
return
