Domestic Hot Water; Gas Supply; Electrical - Worcester 24ijunior Installation And Servicing Instructions

9. Domestic Hot Water

It may be necessary to contact the local Water Company before
connecting the appliance. Where back-flow prevention devices,
including water meters, are fitted the expansion of hot water into
cold water main can be prevented. This can result in a pressure
build-up that may cause damage to the boiler and household
devices such as showers, washing machines etc.
In these cases we recommend that a mini-expansion vessel be
fitted adjacent to the boiler in the cold water pipe.
In Eire advice on backflow protection is given IS813 Annex M4.3
and M4.4.
The connection in the domestic water system should be in
copper pipe.
The domestic hot water circuit of the appliance is suitable for a
mains pressure of up to 10bar. A pressure reducing valve must
be fitted if necessary.
A mains water supply isolating valve is fitted.
The maximum hot water flow rate is set at the factory to 8 l/min
[24i] and 10 l/min [28i] giving a nominal temperature rise of 40
with the temperature control at maximum. This rate is equivalent to
a Specific Rate of 11.2 l/min [24i] and 13.1 l/min [28i] at a rise of
30 o C. Refer to Table 6. The temperature rise, upto the maximum, is
maintained by the automatic modulation of the heat input. In winter
(when the mains water temperature is lower) it may be necessary to
reduce the water flow at the tap or shower to maintain the maximum
delivery temperature.
It is recommended that long pipe runs to taps or showers are
insulated to prevent the rapid cooling of the water.
Hot and cold taps and mixing valves must be suitable for the
available mains pressure.
No anti-syphonage arrangements are necessary for fixed head
showers. 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 its immersion in the water. Alternatively the
shower can be fitted with an anti-syphonage device at the flexible
hose connection. Thermostatically controlled or pressure
balancing shower valves will give extra comfort and guard
against extreme temperature.
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-
syphon arrangements are needed.
LIME SCALE: In areas of temporary hardness [>200ppm of
calcium carbonate] it is suggested that a proprietary scale reducer
is fitted in the mains cold water connection to the appliance.
Installation of a scale inhibitor assembly must be in accordance
with the requirements of the local Water Company. The water
hardness can be determined by reference to the local Water
Company.
An isolating valve should be fitted to allow servicing.

10. Gas Supply

The appliance requires a maximum of 2.74 m
[28i] of natural gas (G20) or 1.06 m
propane (G31). Refer to Table 7.
A natural gas appliance must be connected to a governed meter.
The installation and connection of the gas supply to the
appliance must be in accordance with BS6891.
The meter (NG) or regulator (LPG) and the pipework to the
appliance must be checked, preferably by the gas supplier, to
ensure that a dynamic pressure of 20mbar for natural gas or
37mbar for propane is available at the appliance (contact gas
supplier if in doubt) equivalent to about 18.5mbar [NG] or
36mbar [LPG] respectively at the gas valve inlet pressure
connection and that the gas flow is adequate for all the installed
gas appliances operating together.
o C
3 3
/h [24i], 3.17m /h
3 /h [24i], 1.23m 3 /h [28i] of
Safety Check: If there is an electrical fault after installation
check for fuse failure, short circuits, incorrect polarity of
connections, earth continuity or resistance to earth.
Mains supply: 230V ~ 50 Hz 150watts.
External fuse 3A to BS1362. Internal fuses F1-T2A, F2-TI.25A
(20mm). Spare internal fuses are supplied with the appliance.
The mains cable must be 0.75mm
Table 16 and must be connected to the terminal ST2 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.
The Earth lead must still be slack when the other leads are taut.
Refer to Fig 29.
The appliance must be earthed.
The wiring between the appliance and the electrical supply shall
comply with current IEE wiring regulations (and any local reguations
which apply) for fixed wiring to a stationary appliance.
NB. It must be possible to completely isolate the appliance with at
leaste 3mm contact separation in both poles.
A room thermostat or an externally mounted programmer must be
suitable for mains voltage operation. The leads must be securely fixed
in the cable clamps (see Fig 31).
A facia mounted digital programmer or mechanical timer or
receiver for wireless programmable room thermostat is available as
an optional extra. Instructions are supplied with the product.
On very rare occasions it may be necessary to fit an external
frost thermostat to protect remote parts of the system. In this
case refer to the WHS Technical Department for more
information
Tel: 08705 266241 (UK)
. 01 494 0099 (Eire)
10

11. Electrical

2
(24x0.20 mm) to BS6500 -