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5 Water System
5.1 General
This boiler is designed for use as part of a sealed water
central heating system with fully pumped circulation. The
pump, expansion vessel and associated safety devices are all
tted within the boiler.
An options board accessory is available to link the internal
programmer with a Honeywell S or Y plan system.
5.2 Safety Valve
The safety valve is an integral part of the boiler and it cannot
be adjusted. The pipe from the safety discharge valve must
not discharge above an entrance, window or any type of
public access area.
5.3 Expansion Vessel
The boiler has an integral expansion vessel with a capacity of
8 litres (1.76 gallons), with a charge pressure of 0.5bar.
NOTE: The expansion vessel volume depends on the total
water system volume and the initial system design pressure.
In GB, Guidance on vessel sizing is also given in the current
issue of BS5449 and BS7074 Part 1.
In IE, current edition of I.S.813 “Domestic Gas Installations”.
5.4 Flow Rate
If it is necessary to alter the ow rate, the system can be
tted with a lockable balancing valve in the main ow or
return pipes shown as valve “A” in diagram 5.1. The ow rate
through the boiler must not be allowed to fall below that given
in section 1 - Specication Table.
5.5 Bypass
The boiler is tted with an automatic bypass which can be
adjusted to suit your system requirements.
Ensure that under no circumstances does the ow rate drop
below the gure specied, refer to section 1 - Specication
Table.
5.6 Filling the Sealed System
Provision for lling the system at low level must be made, see
diagram 5.2. There must be no permanent connection to the
mains water supply, even through a non-return valve.
NOTE: It is important that ttings used for connection
to potable water comply with the water undertakings
requirements.
5.7 Draining Points
Draining taps must be provided at all the low points of the
system, which will allow the entire system to be drained.
Draining taps shall be to the current issue of BS2879.
Drain points for the appliance are provided at the positions
shown in diagram 8.1.
5.8 Domestic Hot Water Cylinder
SINGLE FEED INDIRECT CYLINDERS ARE NOT SUITABLE
AND SHOULD NOT BE USED. The domestic hot water
cylinder must be of the double feed indirect coil type. It must
be suitable for working at a gauge pressure of 0.35bar above
the safety valve setting.
13486
5.9 Water Treatment
Existing system- It is ESSENTIAL that prior to installing the
new boiler the system is thoroughly ushed.
New system- For optimum performance after installation, the
boiler and its associated central heating system should also
be ushed.
Flushing should be carried out in accordance with BS7593:
2006 using a cleanser such as Sentinel X300 or X400, Fernox
Restorer or Salamander corrosion guard cleaner.
IMPORTANT: Ensure all cleanser is removed from the whole
system before adding an inhibitor.
For long-term corrosion protection, after ushing, an inhibitor
suitable for stainless steel exchangers should be used, refer
to the current issue of BS 5449 and BS 7593 on the use of
inhibitors in central heating systems. Examples are Sentinel
X100 Fernox Protector or Salamander corrosion guard
inhibitor.
Diagram 5.1
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