Ideal-Standard A5322AA User Manual

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Figure 3 Backflow risk from a fluid category 3
Figure 4 Backflow risk from a fluid category 5
zone of backflow
risk for longer
hose
spill
over
level
bath or shower tray
25mm minimum air gap
required if check valves are
not fitted
spill over
level
washbasin
zone of
backflow risk
for shorter
hose
no additional
backflow protection
required
cold and hot water supplies
to shower valve will need
additional check valves on each
service if longer hose is fitted
zone of backflow risk
for restrained hose
which is longer than
system design hose
- not permitted -
zone of backflow
risk for unrestrained
hose
zone of backflow risk
for restrained hose
w.c.
spill-over
level
shower tray
or bath tub
bidet
w.c.
spill-over
level
restrained hose giving
the 25 mm air gap is
permitted
25mm
minimum
unrestrained
hose would
not be
permitted
WATER REGULATIONS
3
CATEGORIES OF RISK
The water regulations published in 1999* take a new approach to backflow in that they look at
different categories of risk. The installer must assess the risk from the various categories of fluid in
adjacent appliances before determining the level of backflow protection required for a particular
installation. Figures 3 & 4 describe the protection required in various installations.
CATEGORY 3 RISK
Water in a shower tray, basin or bathtub is considered to be a fluid category 3 risk which is a fluid
which represents a slight health hazard if it were to find it’s way back into the supply pipe. For this
reason it must not be possible for any flexible shower head to be able to enter any adjacent
washbasin, bath or shower tray unless appropriate protection is employed. (See Figure 3). If it is
desired to allow the hand spray to be used inside say a bathtub or a basin it is essential that double
check valves be fitted to the inlet on both hot and cold supplies to the thermostatic valve. Alternatively
single check valves can be fitted at the
inlets and an additional check valve should
be fitted in the valve outlet.
No check valves need be fitted if the hand
spray is prevented from reaching closer
than 25mm of the spill over level of any
such fixture.
CATEGORY 5 RISK
Water in a Sink, WC or Bidet is considered
to be a fluid category 5 risk which is a fluid
which represents a serious health hazard if
it were to find it’s way back into the supply
pipe. For this reason it must not be
possible for any flexible shower head to be
able to enter any adjacent Sink, WC or
Bidet. If the flexible hose to be fitted could
reach into any such vessel, the
requirements to the system design are so
onerous it is better not to fit a flexible.
Rather, a fixed overhead showerhead
should be considered. (See Figure 4).
It will also be seen that this risk could
change should the hose be taken out of
the restraining device or should a longer
replacement hose be fitted at a later date.
Installers and householders are advised to
take account of these factors when fitting
replacement hoses.
For pumped applications the pipe
supplying the pump must not in addition
supply an ascending spray bidet.

Ideal-Standard A5322AA Specifications

General

Brand	Ideal-Standard
Model	A5322AA
Category	Control Unit
Language	English