Domestic Hot Water - Worcester OIL HEATSLAVE 12/14 Installation And Servicing Instructions

12. Domestic Hot Water

The following are general requirements and, if necessary,
reference should be made to the local Water Company before
fitting the appliance.
12.1 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 can be fitted within the casing of the appliance
if necessary.
The final 600mm of the mains cold water connection to the
appliance should be made in copper tube only.
The appliance is suitable for a mains cold water supply having a
maximum pressure of up to 10 bar (145 lb/in
reducing valve must be fitted if the mains pressure exceeds 10
bar.
12.2 Domestic Hot Water Supply and Flow Regulation
As with all mains fed systems, the flow rate of water obtainable
from individual taps will vary in relation to the number of
outlets operated simultaneously.
The flow rate will depend on the cold mains supply pressure
available to the property and the diameter and length of
pipework making up the domestic water distribution system.
When more than one outlet is used at once, starvation of water
flow may occur at one or more outlets. Where this is a problem
flow balancing valves or Ball-O-Fix valves should be installed at
the appropriate outlets.
The 12/14 and 15/19 appliances are fitted with a water flow
restrictor. The maximum flow of domestic hot water available
from the appliances is 15 litres/min (+ or - 15%) (3.3
gallons/min) and requires a minimum mains cold supply
pressure of 1.6 bar (22 lb/in
The 20/25 and 26/32 appliances are not fitted with a flow
restrictor and therefore the flow rate is only limited by the water
supply pressure. This can be manually adjusted at the mains
cold water inlet isolating valve. The maximum recommended
domestic hot water flow rate from the 20/25 appliance is 17
litres/min (3.7 gallons/min). The maximum recommended
domestic hot water flow rate from the 26/32 appliance is 22
litres/min (4.8 gallons/min).
The temperature of hot water drawn will vary with the flow rate
at the taps and the appliance operating temperatures. It is usual
that flow rates (and thus temperatures) are controlled at the tap,
but if a more permanent setting is required, a mixing valve can
be fitted.
If there are long pipe runs to the taps or shower, it is
suggested that they be insulated to prevent the rapid cooling
of residual hot water in the pipes after the tap has been
turned off.
NOTE: The flow restrictor contained within the flow switch
housing is plastic. Do not allow the housing to become hot
during soldering operations.
12.3 Taps and Valves
Hot and cold taps and mixing valves used with this appliance
must be suitable for operating at a mains pressure of up to 10
bar (145 lb/in 2 ).
12.4 Showers (Fixed Head Type)
No anti-syphonage arrangements
Thermostatically controlled shower valves will give extra
comfort and guard against the flow of water at too high a
temperature.
12.5 Showers (Loose or Flexible Head Type)
A loose head shower hose must be fixed so that the head cannot
fall closer than 25mm (1 in) above the top edge of the bath to
prevent its immersion in bath water. Alternatively the shower
must incorporate or be fitted with an anti-syphonage device at
the point of the flexible hose connections.
Thermostatically controlled shower valves will give extra
comfort and guard against the flow of water at too high a
temperature.
2 ). A pressure
2
) to attain this level.
are necessary.
12.6 Bidets
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.
12.7 Use in Hard Water Areas
In areas of exceptionally hard water supply, it is recommended
that an In-line scale inhibitor be fitted.
Installation should be strictly in accordance with the
requirements of the local Water Company. An isolating valve to
facilitate servicing should be incorporated.
The water hardness may be determined using the standard test
paper or by reference to the local Water Company.
Further information may be obtained from Worcester Heat
Systems Ltd.
IMPORTANT: 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.
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