Ideal-Standard ALTO ECOTHERM A4741AA User Manual

CATEGORIES OF RISK
The water regulations published in 1999* take a new approach to backow in that they look at different
categories of risk. The installer must assess the risk from the various categories of uid in adjacent appli-
ances before determining the level of backow 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 uid category 3 risk which is a uid which
represents a slight health hazard if it were to nd it’s way back into the supply pipe. For this reason it must
not be possible for any exible 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 tted to the inlet on both
6
3 WATER REGULATIONS
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
hot and cold supplies to the thermostatic
valve. Alternatively single check valves
can be tted at the inlets and an additional
check valve should be tted in the valve
outlet.
No check valves need be tted if the hand
spray is prevented from reaching closer
than 25mm of the spill over level of any
such xture.
CATEGORY 5 RISK
Water in a Sink, WC or Bidet is considered
to be a uid category 5 risk which is a uid
which represents a serious health hazard
if it were to nd it’s way back into the
supply pipe. For this reason it must not be
possible for any exible shower head to
be able to enter any adjacent Sink, WC or
Bidet. If the exible hose to be tted could
reach into any such vessel, the require-
ments to the system design are so one-
rous it is better not to t a exible. Rather,
a xed 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 tted at a later date.
Installers and householders are advised to
take account of these factors when tting
replacement hoses.
For pumped applications the pipe supply-
ing the pump must not in addition supply
an ascending spray bidet.
Category 5 hose retaining instruction on
page 6. (See Figure 5)
Fig. 3 Backow risk from a uid category 3
Fig. 4 Backow risk from a uid category 5

Ideal-Standard ALTO ECOTHERM A4741AA Specifications

General

Brand	Ideal-Standard
Model	ALTO ECOTHERM A4741AA
Category	Mixer
Language	English