Domestic Hot Water; Electrical - Worcester 26CDi XTRA Installation And Servicing Instructions

8. Domestic Hot Water

8.1 The following are general requirements and, if necessary,
reference should be made to the local Water Company before
fitting the appliance.
8.2 MAINS COLD WATER INLET. Devices capable of preventing
the flow of expansion water must not be fitted unless separate
arrangements have been made. An expansion vessel connection
point is provided within the appliance.
1
An Rc / connection is provided. A Zilmet Z160 is the preferred
2
type. A thread sealant compatible with potable water must be
used.
8.3 The final 600mm of the mains cold water connection to the
appliance should be made in copper tube only.
8.4 The appliance is suitable for a mains pressure of up to
2
10 bar (150 lb/in ).
8.5 The appliance is fitted with a mains supply isolating valve.
8.6 The maximum domestic hot water flow rate is
8.0 litres/min (±15%) (1.8 gallons/min).
8.7 In winter (when the mains inlet water temperature is lower) a
reduced flow rate at the taps may be required to achieve the
type of hot water delivery temperature available in warmer
weather.
8.8 It is suggested that long pipe runs to the taps or shower
should be insulated to prevent the rapid cooling of domestic hot
water after a tap or shower has been turned off.
8.9 Hot and cold taps and mixing valves used with this
appliance must be suitable for operating at mains pressure and
temperatures of 65°C.
8.10 No anti-syphonage arrangements are necessary except for
some loose head showers.
See also Section 9.12 following.
8.11 Thermostatically controlled or pressure equalising shower
valves will guard against the flow of water at too high a
temperature.
8.12 The head of a loose head shower must not fall closer than
25 mm (1in) above the top edge of the bath to prevent its
immersion in bath water. Alternatively the shower must be fitted
with an anti-syphonage device at the point of the flexible hose
connections.
8.13 The supply of hot and cold mains water direct to a bidet is
permitted (subject to local Water Company requirements),
provided that the bidet is of the over-rim flushing type. The
outlet(s) should be shrouded and unable to have any temporary
hand held spray attached. No anti-syphonage arrangements are
necessary.
8.14 As the maximum temperature of the water to water heat
exchanger is limited by the control circuit, there is normally no
need for water treatment to prevent scale accumulation. In
exceptional circumstances a device to prevent scale formation
can be fitted.
Installation of a scale inhibitor assembly should be in
accordance with the requirements of the local Water Company.
An isolating valve should be fitted to allow servicing. The water
hardness can be determined using a standard test paper or by
reference to the local Water Company.

9. Electrical

See figs. 9, 10, 11, 12, 13, 14 and 27.
9.1 MAINS SUPPLY.
230 V~, 50 Hz, 180 watts.
External Fuse. 3A.
Internal Fuses: T 2A (F1) and T 1.25A (F2).
Spare internal fuses are supplied at the rear of the facia, next to
the pressure gauge.
9.2 It must be possible to completely isolate the appliance.
9.3 The following connection alternatives must be used:
A 3 amp fused three-pin plug and unswitched shuttered socket
outlet (both complying with the requirements of BS 1363) or a
double pole isolator with a contact separation of 3mm in all
poles and supplying the appliance and controls only.
9.4 The appliance must be earthed.
9.5 Mains Cable. 0.75 mm
BS 6500 Table 16.
The mains cable must be connected into the terminal ST12,
marked L (Brown or Red lead), N (Blue or Black lead) and the
earth stud and be held securely in the cable clamp. For access
undo the three bottom screws and remove the facia access cover.
See fig. 9.
9.6 The wiring between the appliance and the electrical supply
shall comply with current IEE Wiring Regulations and any local
regulations which apply.
9.7 If a room thermostat and/or external programmer is to be
fitted refer to figs. 12, 13, and 14. The devices must be suitable
for use with mains voltage.
9.8 Facia mounted programmers are available as optional
extras. Instructions are supplied with the programmer kits.
9.9 A time switch or programmer can be fitted externally to the
appliance.
9.10 The boiler is fitted with an internal frost thermostat which
will protect the boiler from frost damage, as long as the mains
switch on the boiler is in the on position. However, if frost
protection is necessary for the system, please contact the
Worcester Heat Systems Technical Helpline. Tel: 01990 266241.
9.11 SAFETY CHECK
After installation or in the event of an electrical fault the
electrical system shall be checked for short circuits, fuse failure,
incorrect polarity of connections, earth continuity and resistance
to earth.
10
2
(24 x 0.20mm) to