andrews 10/105 Installation And Service Manual page 18

Fig. 7
D3
Expansion
vessel
D4
Temperature
pressure relief
valve
Cold water
inlet of
water
heater
D6
D2 Check valve/
D2 Pressure
expansion valve
D5 tundish
Fig. 8
Balanced cold
water take - off
(if required)
D7 Hose
assembly
reducing
valve
strainer
Cold water feed
3.8.3 Water Connections - Unvented Systems
Unvented Systems should be fitted by an Approved Installer.
When used in an unvented system, the Andrews Water Heater
will supply hot water at a pressure of 3.5bar (50.8lbf/in
provided that this pressure is available at the mains feed. During
conditions of no-flow, system pressure may rise to a maximum
of 6bar (87lbf/in 2 ) whilst the burner is operating. When testing
the system, it is recommended that a maximum test pressure of
8.62bar (125lbf/in 2 ) is employed.
The heater can be used on unvented hot water storage systems,
with the addition of an Unvented Systems Kit, available from
Andrews Water Heaters.
All fittings and materials must be suitable for use with drinking
water and listed in the current Water Research Centre "Materials
and Fittings Directory".
Installation of unvented hot storage water systems must comply
with part G of Schedule 1 of the Current Building Regulations.
See
Fig.8 lists and illustrates the component parts of the
Unvented Systems Kit.
Fig.6 illustrates the general arrangement of the
components.
The Wall Mounting Kit is available as an optional extra.
Items D4/D6 must be fitted into the Temperature Relief
port (see Fig.7).
When assembling items D1 and D2 care must be taken to
ensure that the flow arrows marked on the components are
pointing in the direction of flow i.e. towards the water heater.
The cold water for services may be drawn from the 22mm
compression port on item D1(a). The water pressure at this point
will be similar to that available at the hot water outlet of the
water heater. If port (a) is not used it should be sealed with the
blanking plug supplied.
If higher flow rates are required for the cold water services a
suitable "tee" fitting should be included in the pipework upstream
of item D1.
The pipework fitted to both tundish outlets should be at least
28mm diameter and should be terminated at a suitable drain
(see Current Building Regulations Approved Document G3).
2 )
18