Domestic Hot Water; Electrical - Bosch Greenstar ZWBR 7-25 A 23 Installation And Servicing Instructions

Wall mounted condensing boiler for central heating and mains fed domestic hot water
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10. Domestic Hot Water

Any regulations specified by the local water company must be
observed.
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 supply having a maximum
pressure of 8 bar. A pressure reducing valve must be fitted, if
necessary.
The hot water outlet temperature is set to be capable of
achieving a maximum of 55°C. When operating normally the
boiler operates occasionally to maintain an 8 litre heat store at
this temperature ensuring that hot water is available at the tap
or shower almost immediately it is required. The maximum
temperature and the frequency of the recharge of the heat store
may be reset.
The maximum water flow rate is factory set at 9.5l/min to give
temperature rise of 35°C. If a higher rise is required then the flow
must be reduced at the tap and the discharge temperature will
rise up to the maximum set figure.
The temperature rise, upto the maximum set by the user, is
automatically maintained by the modulation of the heat input.
In winter, when the mains temperature is very low, the water
flow, adjusted at the tap or shower, should be reduced to
maintain the required delivery temperature.
It is suggested that long pipe runs to taps or showers be
insulated to prevent the rapid cooling of the water.
All types of single lever mixer taps and thermostatic mixer units
suitable for a mains pressure of up to 8 bar can be used.
The head of a loose-head shower must not be allowed to fall
within 25mm of the top the bath to prevent the risk of water
being drawn back into the mains. Alternatively the shower must
be fitted with an anti-syphonage device at the point of the
flexible hose connections.
Over-rim bidets may be connected to the appliance provided
that it is in accordance with the requirements of the local water
company. The outlet(s) should be shrouded and unable to have
any temporary hand held spray attached. No anti-syphonage
arrangements are necessary.
In exceptionally hard water areas a device to prevent scale
formation may be fitted or, alternatively, the maximum
temperature reset to about 45°C which may reduce the risk of
scale formation. The installation of a scale inhibitor assembly
should be in accordance with the requirements of the local water
company. Artificially softened water must not be used. An
isolating valve should be fitted to allow for servicing.
Devices capable of preventing the flow of expansion water must
not be fitted unless separate arrangements have been made.
A Zilmet Z160 expansion vessel is the preferred type. A thread
sealant compatible with potable water must be used.

11. Electrical

Supply: 230V ~ 50Hz 140 watts. External fuse 3A. Protection
IPX4C.
Mains cable: PVC insulated 0.75mm
BS 6500–Table 6. Temperature rated 100°C.
It must be possible to isolate the appliance
The appliance must be earthed.
The appliance must be connected to the mains through a 6A
double pole isolator with a contact separation 3mm in all poles
and supplying the appliance and controls only. The wiring must
comply with the current requirements of the IEE Wiring
Regulations and any local regulations which apply.
To gain access to the mains connection remove the drop down
facia cover. The drop down cover is removed by lowering it to the
horizontal position and pushing firmly upwards at the rear of
the supports to release the cover. Lift cover from the appliance.
Remove the facia connection cover. Refer to Fig.
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.
8
2
(24 x 0.20mm) to

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Greenstar zwbr 11-25 a31Greenstar zwbr 7-25 a23

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