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8. Domestic Hot Water
8.1. If necessary reference should be made to the local water
company before connecting the appliance.
8.2. Devices which would prevent the flow of expansion water
must not be fitted unless separate arrangements have been
made. A mini-expansion vessel can be fitted within the casing if
necessary. A thread sealant suitable for potable water must be
used.
8.3. The last 600mm of mains water pipe before the appliance
must be in copper.
8.4. The domestic hot water circuit of the appliance is suitable
for a mains pressure of upto 10 bar. A pressure reducing valve
must be fitted if necessary.
8.5. A mains supply isolating valve is fitted.
8.6. The DHW pump is set at maximum and must not be
adjusted.
8.7. The maximum hot water flow rate is set at the factory to
12.6 (±15%) l/min giving a nominal temperature rise of 40°C
with the temperature control at maximum. This rate is
equivalent to a specific rate of 16.7 l/min at a rise of 35°C . Refer
to Table 6.
8.8. The temperature rise, upto the maximum set by the user, is
automatically maintained by the modulation of the heat input.
8.9. In winter, when the mains water temperature is very low, the
water flow, adjusted at the tap or shower, should be reduced to
maintain the required delivery temperature.
8.10. It is suggested that long pipe runs to taps or showers be
insulated to prevent the rapid cooling of the water.
8.11. Hot and cold taps and mixing valves must be suitable for
the available mains pressure. If necessary a pressure reducing
valve should be fitted.
8.12. No anti-syphonage arrangements are necessary for fixed
head showers.
8.13. The hose of a loose head shower must be fixed so that the
shower head cannot get closer than 25mm to the top edge of the
bath to prevent immersion in the water. Alternatively the shower
can be fitted with an anti-syphonage device at the flexible hose
connection.
8.14. Thermostatically controlled shower valves will give extra
comfort and guard against extreme temperatures.
8.15. Hot and cold mains water direct to a bidet is, subject to the
approval of the local water company, permissible provided that
the bidet is of the overrim flushing type. The outlets must be
shrouded and unable to be fitted with a hand-held spray. No anti-
syphonage arrangements are needed.
8.16. The maximum temperature of the heat exchanger is
limited and there is normally no need for water treatment to
prevent scale formation.
8.17. If the water hardness is very high then an anti-scaling
device can be considered. Further information is available from
WHS Technical Information Department, Telephone 0990
266241.
8.18. The installation of a scale inhibitor must be strictly in
accordance with the requirements of the local water company.
9. Gas Supply
9.1. The appliance requires 4.12 m /h of natural gas (G20) or
3
1.64 m /h of propane (G31). Check that the supply system can
accommodate this together with any other appliances
connected to it. Refer to Table 7.
9.2. A natural gas appliance must be connected to a governed
meter.
9.3. There must be a pressure of 20mbar (G20) or 37mbar (G31)
at the inlet to the appliance. This is equivalent to a pressure of
18.5 - 19.0mbar (G20) or 35 - 35.5mbar (G31) at the inlet to the
gas valve.
3
Fig 8 - System Make Up
1
6
1. Central Heating Return
2. Auto Air Vent
3. Non-return Valve
4. Make-up Vessel
5. Stop Cock
6. Fill Point
10. Electrical
10.1. Mains supply : 230V ~ 50Hz, 180watts. External fuse 3A,
Internal fuses F1 - 2A, F2 - 1.25A (20mm). Spare internal fuses
are supplied with the appliance. Refer to Fig 15.
10.2. The appliance must be earthed.
It must be possible to completely isolate the appliance.
10.3. The mains cable must be 0.75mm2 (24x0.20 mm) to
BS6500-Table 15 or 16.
10.4 The mains cable must be connected to the terminal ST12
marked L (red or brown lead), N (black or blue lead ) and the
Earth stud (green or green/yellow lead) and secured with the
cable clamp. Check that sufficient loose lead has been left to
allow access to the control box. The Earth lead must be still be
slack when the other leads are taut. Refer to Fig 9.
10.5. The connection to the mains must be either: A 3A fused
three-pin plug and unswitched socket outlet, (both complying
with BS1363) or a double pole isolator with a contact separation
of 3mm in all poles and supplying the appliance and controls
only.
10.6. Access to the mains connection on the driver board is
gained by removing the bottom cover from the facia.
Refer to Fig 11.
10.7. A room thermostat or an externally mounted programmer
must be suitable for mains voltage operation and the leads
securely fixed in the clamps provided. The controls must be
earthed at the bracket by the control board. Refer to Fig 10
and 12.
10.8. A programmer, to fit into the facia, is available to control
the CH. Full instructions are sent with the programmer. Refer to
Fig 16.
10.9. A clock, to fit into the facia, is available to control the
operation of the appliance.
8
4
2
3
300mm Above
the Highest Point
of
the System
5
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