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A Boiler
E Sink
F Open end of condensate drainage pipe di-
rect into gully below grating but above water
level
5.8
Water circulation (c.h.)
Detailed recommendations are given in BS
6798, BSEN 12828: 2003, BSEN 12831: 2003
& BSEN 14446: 2004; the following notes are
given for general guidance.
For Ireland (IE), refer to I.S.813.2002.
Pipework
The return temperature must not be lower of
40°C. Copper tubing to BSEN 1057 is recom-
mended for water pipes. Jointing should be ei-
ther with capillary soldered or with compression
fittings.
Where possible pipes should have a gradient
to ensure air is carried naturally to air release
points and water flows naturally to drain taps.
The appliance has a built-in automatic air re-
lease valve, it should be ensured as far as pos-
sible that the appliance heat exchanger is not a
natural collecting point for air.
Except where providing useful heat, pipes
should be insulated to prevent heat loss and to
avoid freezing.
Particular attention should be paid to pipes
passing through ventilated spaces in roofs and
under floors.
By-pass
The appliance includes an automatic by-pass
valve which protects the main heat exchanger in
case of reduced or interrupted water circulation
through the heating system due to the closing
of thermostatic valves or cock-type valves within
the system.
The by-pass is calibrated to assure a minimum
flow of 200-300 lts/hr through the main heat ex-
changer.
If you are installing a system that includes ther-
mostatic radiator valves (TRV) and/or small bore
GENERAL REQUIREMENTS
(8-10 mm) it may be necessary to fit an exter-
nal by-pass to facilitate correct operation of the
boiler.
The fitting of an external bypass helps to pre-
vent and limit system noise.
Air release points
These must be fitted a tall high points where air
will natural collect and must be sited to facilitate
complete filling of the system.
Expansion vessel
The appliance has an integral sealed expansion
vessel to accommodate the increase of water
volume when the system is heated. Refer to Fig.
4.4 on page 29 for its technical data.
If the heating circuit has an unusually high water
content, calculate the total expansion and add
an additional sealed expansion vessel with ad-
equate capacity.
Mains water feed: central heating
There must be no direct connection to the mains
water supply even through a non return valve,
without the approval of the Local Water Author-
ity.
Mains water feed: hot water supply
The domestic section of the boiler is designed to
withstand an internal domestic water pressure
of 10 bar. Where it is likely that the mains do-
mestic water pressure may exceed 5 bar, it is
possible due to internal "water hammer" effects
that the pressure within the domestic system
can increase to a level in excess of the 10 bar
limit.
In these circumstances it is therefore recom-
mended that a 3 bar pressure reducing valve be
fitted to the incoming mains water supply and a
mini expansion vessel installed on the domestic
circuit.
These devices will protect the boiler and the do-
mestic system from damage due to excessive
domestic water pressure.
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