4
SECONDARY
RETURN
COLD
SUPPLY
CHECK
VALVE
SECONDARY
CIRCULATION
PUMP
COLD
INLET
CONNECTION
SWEPT
TEE
3.0 INSTALLATION – GENERAL
(FIGS 3 & 5)
3.1 PIPE FITTINGS
All pipe fittings are made via 22mm compression
fittings directly to the unit. The fittings are threaded
3/4”BSP male parallel should threaded pipe
connections be required.
3.2 COLD FEED
A 22mm cold water supply is recommended however,
if a 15mm (1/2”) supply exists which provides suffi-
cient flow this may be used (although more flow noise
may be experienced).
A stopcock or servicing valve should be incorporated
into the cold water supply to enable the Heatstore
HSU and its associated controls to be isolated and
serviced.
3.3 COLD WATER COMBINATION VALVE (FIG 1)
The Cold Water Combination Valve can be connected
anywhere on the cold water mains supply prior to the
Expansion Vessel (see Fig. 5).
The Cold Water Combi-
nation Valve is installed as a complete one-piece unit.
The valve incorporates the Pressure Reducer, Strainer,
Expansion Valve and Check Valve. Ensure that the
valve is installed with the direction of flow arrows
pointing in the right direction. No other valves should
be placed between the Cold Water Combination Valve
and the Heatstore HSU unit. The Expansion Valve con-
nection must not be used for any other purpose.
FIG. 1 Cold Water Combination Valve
FIG. 2 Secondary circulation connection
3.4 DRAIN TAP
A suitable draining tap should be installed in the cold
water supply to the Heatstore HSU unit between the
Cold Water Combination Valve and the heater at as
low a level as possible. It is recommended that the
outlet point of the drain pipework be at least 1 metre
below the level of the heater (this can be achieved by
attaching a hose to the drain tap outlet spigot).
3.5 EXPANSION VESSEL
The Expansion Vessel accommodates expansion that
results from heating the water inside the unit. The unit
is pre-charged at 3.5 bar. The Expansion Vessel must
be connected between the Cold Water Combination
Valve and the Heatstore HSU (see Fig. 5). The loca-
tion of the Expansion Vessel should allow access to
recharge the pressure as and when necessary, this
can be done using a normal car foot pump. It is recom-
mended that the Expansion Vessel is adequately sup-
ported. An Expansion Vessel wall mounting bracket is
supplied for this purpose
3.6 SECONDARY CIRCULATION
If secondary circulation is required it is recommended
that it be connected to the Heatstore HSU as shown
in Fig. 2 via a swept tee joint into the cold feed to the
unit.
The secondary return pipe should be in 15mm pipe
and incorporate a check valve to prevent backflow. A
suitable WRAS approved bronze circulation pump will
be required. On large systems, due to the increase in
system water content, it may be necessary to fit an
additional expansion vessel to the secondary circuit.
this should be done if the capacity of the secondary
circuit exceeds 10 litres.
Pipe capacity (copper)
15mm o/d = 0.13 l/m (10 litres = 77m)
22mm o/d = 0.38 l/m (10 litres = 26m)
28mm o/d = 0.55 l/m (10 litres = 18m)
Secondary circulation is NOT recommended for direct
electric units being used on Off Peak electricity tar-
iffs.
3.7 OUTLET
The hot water outlet is a 22mm compression fitting
located at the top of the cylinder. Hot water distribu-
tion pipework should be 22mm pipe with short runs of
15mm pipe to terminal fittings such as sinks and ba-
sins. Pipe sizes may vary due to system design.
EXPANSION VALVE
COLD MAINS
CONNECTION
(22mm)
EXPANSION VALVE
OUTLET (15mm)
OUTLET
CONNECTION
(22mm)
PRESSURE
REDUCING
VALVE
HOUSING
PRESSURE
REDUCING
VALVE
CARTRIDGE (3.5 bar)
