bath shower mixer
5
Service
valves
Balanced cold mains supply
Cold mains supply
Expansion
vessel
Pressure
reducing valves
Stop tap
Unvented
hot water
storage unit
Safety devices
not shown
Mixer
CH flow
Cold
mains
supply
Hot water
CH return
Service
valves
Stop
tap
Expansion
vessel
Pressure
reducing valve
Combination
boiler
Mixer
*Fig.4
*(diagrammatic view – not to scale)
Instantaneous gas-heated systems,
e.g. combination boilers (g.4)
The shower control MUST be installed with a
multi-point gas water heater or combination
boiler of a fully modulating design (i.e.
to maintain relatively stable hot water
temperatures).
An expansion vessel MAY be tted, and regularly
maintained, to prevent the shower mixer
being damaged by excess pressures. This may
already be installed within the boiler (check with
manufacturer) and is in addition to the normally
larger central heating expansion vessel.
Unvented mains pressure systems (g.5)
The shower control can be installed with an
unvented, stored hot water cylinder.
For systems with no cold water take off after the
appliance reducing valve, it will be necessary to
t an additional drop tight pressure-reducing
valve when the mains pressure is over 5 bar. The
drop tight pressure reducing valve must be set at
the same value as the unvented package pressure
reducing valve.
Note: An additional expansion vessel may be
required if a second pressure-reducing valve is
installed. This does not apply to packages with a
cold take off after the pressure-reducing valve to
the cylinder.
*Fig.5
*(diagrammatic view – not to scale)
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