Dual control thermostatic mixer
5
Blender
valve
Flow
Cold mains supply
Hot
water
Stop tap
Expansion
vessel
Pressure
reducing valve
Return
Service
valves
Mixer
Boiler
Pipework to
fixed head
Fig.4
(
diagrammatic view – not to scale)
Pipework to
fixed head
Fixed head
Service
valves
Other draw-offs
Gate
valve
Vent pipe
tee
Cold supply
Hot
supply
Alternative
connection
Mixer
Stop
tap
Cold
water
mains
supply
Hot
water
cylinder
Drain
valve
Cold water
cistern
1 metre
minimum
Fig.5
(
diagrammatic view – not to scale)
c) Mains pressurised thermal store
systems (fig.4)
Packages of this type, fitted with a tempering
valve (blender valve) can be used. A drop tight
pressure reducing valve MUST be fitted if the
supply pressures exceed 5 bar running.
An expansion vessel (shown in
fig.4
) MUST be
fitted, and regularly maintained, to ensure the
unit is not damaged by excess pressures. This
may already be installed externally or internally
within the thermal store (check with thermal
store manufacturer).
d) Gravity fed systems (fig.5)
The shower control MUST be fed from a cold
water cistern and hot water cylinder providing
nominally equal pressures. There must be a
minimum of one metre head of water. The
minimum head distance is measured from the
base of the cold water cistern to top of the
showerhead
(fig.5)
.
e) Pump assisted gravity systems (fig.6)
The pump must be fed from a cold water cistern
and hot water cylinder providing nominally
equal pressures. The pump must be capable of
maintaining a minimum running pressure of one
bar
(fig.6)
.
