
9. Domestic
Hot
Water
I
9.1 The following are general requirements and,
if
necessary,
reference should be made to the local Water Company before
fitting the appliance.
9.2
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 (Rc'/2)
is
provided adjacent to the
flow
switch within the
appliance.
A Zilmet 2160 expansion vessel
is
the preferred type. A thread
sealant compatible with potable water must be used.
9.3 The
final
600 mm
of
the mains cold water connection to the
appliance should be made
in
copper tube only.
9.4 The appliance
is
suitable
for
a mains pressure of up to 10
bar (150 lb/in').
9.5 The appliance
is
fitted with a mains supply isolating valve.
9.6
The
maximum
domestic
hot
water
flow
rate
is
8.5
litres/min. (± 15%)
(1
.87 gallons/min.).
9.7
In
winter (when the mains inlet water temperature
is
lower)
a reduced
flow
rate at the taps
will
be required to achieve the
maximum hot water delivery temperature available
in
warmer
weather.
9.8
It
is
a requirement
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. Refer
to
BS5546:1990.
9
9.9 Hot and cold taps and mixing valves used with this appli-
ance must be suitable
for
operating
at
a pressure ofup to 10 bar
(150 lb/in').
9.10
No
anti-syphonage arrangements are necessary except for
some loose head showers. See also Section
9.11
following.
9.11 Thermostatically controlled or pressure equalising shower
valves
will
guard against the
flow
of water at too high a temper-
ature.
9.12
The
head of a loose head shower must not
fall
closer than
25
mm
(1
in.)
above the
top
edge of the
bath
to
prevent its
immersion
in
bath water. Alternatively the shower must be
fit-
ted with an anti-syphonage device
at
the point of the flexible
hose connections.
9.13
The
supply
of
hot and cold mains water direct
to
a bidet
is
permitted, (subject to local Water Company requirements),
pro-
vided 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
nec-
essary.
9.14
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
accor-
dance 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.