INSTALLATION
SECTION 3
WATER
CONNECTIONS
UNVENTED
SYSTEMS
16
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 (51lbf/in
2
), 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 8.6bar (125 lbf/in
2
)is employed.
The heater can be used on unvented hot water storage systems, with the addition of an
Unvented Systems Kit, these are available from Andrews Water Heaters.
See Parts List Pages 40 - 42. The Wall mounting assembly is available as an optional extra.
Item C5 must be fitted into C6 and fitted on the hot water outlet nipple located at the
rear of heater models OFS108 & OFS163.
When assembling items C1 and C2, 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
C1(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.
C4
Expansion Vessel
C8
Wall bracket Assembly
C7
Hose Assembly
C6
2” Sq Tee
Cold Water
Inlet of
Water Heater
C2 Check Valve/
C3 Expansion Valve
(a)
Balance Cold Water
Take-off
(if required)
C1 Pressure Reducing
Valve / Strainer
Cold Water Inlet
NB. Tees, elbows, stop valves and
pipework not supplied.
OPTIONAL PARTS
C7 Tundish
C5
Temperature/
Pressure
Relief Valve
