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6.0 System Details
© Baxi Heating UK Ltd 2008
6.8 Domestic Hot Water Circuit (Fig. 7)
1. All DHW circuits, connections, fittings, etc. should be fully
in accordance with relevant standards and water supply
regulations.
2. Your attention is drawn to:
for GB: Guidance G17 to G24 and recommendation R17 to
R24 of the Water Regulations Guide.
for IE: the current edition of I.S. 813 “Domestic Gas
Installations”.
3. A single check valve must be fitted as shown in Fig. 7 to
prevent backflow to the supply pipe and to ensure the
efficient operation of the expansion vessel which is required
to accommodate the thermal expansion of the water.
4. When the domestic water 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
(eg. Zilmet 160ml, R
1
/
2
15bar).
5. 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.
6. The boiler’s maximum working mains pressure is 8 bar,
therefore all pipework, connections, fittings, etc. should be
suitable for pressures in excess of 8 bar. A pressure reducing
valve must be fitted for pressures in excess of 8 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. Contact your
Water Distribution Company for advice on suitable devices.
Boiler
Other Tap
Outlets
Expansion
Vessel
To Hot
Taps
Check
Valve
Pressure Reducer
Valve
Stop Tap
Fig. 7