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SEALED SYSTEM REQUIREMENTS
Working pressure 6 bar maximum.
Particular reference should be made to BS. 6644 and Guid-
ance note BG01 "Automatically controlled steam and hot water
boilers" published by the Health and Safety Executive.
The information and guidance given below is not intended
to override any requirements of either of the above publica-
tions or the requirements of the local authority, gas or water
undertakings.
In general commercial closed pressurised systems are provid-
ed with either manual or automatic water make up.
In both instances it will be necessary to fit automatic con-
trols intended to protect the boiler, circulating system and
ancillary equipment by shutting down the boiler plant if a
potentially hazardous situation should arise.
Examples of such situations are low water level and operat-
ing pressure or excessive pressure within the system. De-
pending on circumstances, controls will need to be either
manual or automatic reset. In the event of a shutdown both
visual and audible alarms may be necessary.
Expansion vessels used must comply with BS. 4814 and must
be sized on the basis of the total system volume and initial
charge pressure.
Initial minimum charge pressure should not be less than 0.5
bar (7.2psi) and must take account of the static head and
specification of the pressurising equipment. The maximum
water temperatures permissible at the point of minimum pres-
sure in the system are specified in Guidance Note PM5.
When make up water is not provided automatically it will be
necessary to fit controls which shut down the plant in the
event of the maximum system pressure approaching to within
0.35bar (5psi) of the safety valve setting.
Other British Standards applicable to commercial sealed sys-
tems can be found on page 8.
CONDENSATE DRAIN
Condensate drains are provided on the boiler. These drains
must be connected to a drainage point on site. All pipework
and fittings in the condensate drainage system MUST be
made of plastic solvent weld type - no other materials may be
used.
IMPORTANT. Any external runs must be insulated to avoid
freezing in cold weather causing a blockage.
The routing of the drain must be made to allow a minimum fall
of 2.5° away from the boiler, throughout its length.
If the vertical flue header is specified the flue manifold conden-
sate drain connection must also be connected in the same
manner.
BOILER WATER CONNECTIONS
The boiler flow and return pipes are terminated with 2 x 1"BSP
male connections at the rear of the appliance for the 303 and 2
x 11/4" for the 304 and 305 and 2 x 11/2" for the 306 and 307.
Water returning from the system should be connected to the
lower header pipe, with the flow water connection coming from
a top header pipe.
All flow and return pipework must be independently supported.
Plastic plugs fitted on the open ends of the flow and return
pipes must be removed before connecting the system pipe-
work.
An air vent must be provided immediately after the flow con-
nection.
If installing the boiler onto an existing system it is strongly rec-
ommended that the system be thoroughly flushed before con-
necting the boiler. When connecting to a new system it is still
important to flush the whole system in accordance with the
relevant standards.
Note.
Connection to the boilers using manifolds must use a reverse
return principle to ensure equal flow distribution through both of
the modules.
Connection of opposing flow and return points can be made
either on the LH side or RH side, dependent upon the particular
needs of the boiler installation.
14
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