Potterton Performa 24 Installation & Servicing Instructions Manual page 11

Other Tap
Outlets
Expansion
Vessel
Check
Valve
Pressure
Reducing Valve
Stop Tap
Boiler
To Hot
Taps
Fig. 11
6.0 System Details
6.8 Domestic Hot Water Circuit
1. All DHW circuits, connections, fittings, etc.
should be fully in accordance with relevant
standards and water supply bye-laws.
2. Your attention is drawn to:
IRN 116 and Byelaw 90 and 91.
Sealed primary circuits and/or secondary hot
water systems shall incorporate a means for
accommodating the thermal expansion of water
to prevent any discharge from the circuit and/or
system, except in an emergency situation.
3. When the system includes any device which
prevents water expanding back towards the
supply (check valve, loose jumpered stopcock,
water meter, water treatment device), then an
expansion vessel must be fitted (e.g. Zilmet
160ml, R 1 / 15bar).
2
To comply with Byelaw 91, a check valve must
also be fitted on the supply as shown, to ensure
efficient operation and also to prevent the reverse
flow of hot water into the supply pipe.
4. If the hot water expansion is not provided for,
then high pressures can develop which may
result in damage to fittings and devices on the
system.
5. The boiler's maximum working mains pressure
is 8 bar, therefore all pipework, connections,
fittings, etc. should be suitable for pressures in
excess of 10 bar. A pressure reducing valve must
be fitted for pressures in excess of 10 bar. The
manufacturer of any outlet fittings, such as a
shower valve, may require a lower maximum
pressure. The pressure reduction must take
account of all fittings connected to the DHW
system.
6.9 Showers
1. If a shower control is supplied from the
appliance it should be of the thermostatic or
pressure balanced type. Thermostatic type
shower valves provide the best comfort and
guard against water at too high a temperature.
Existing controls may not be suitable - refer to the
shower valve manufacturer.
6.10 Hard Water Areas
1. If the area of the installation is recognised as a
HARD WATER AREA then a suitable device
should be fitted to treat the mains water supply to
the boiler.
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