12
Carefully remove any scale from the surface of the
element(s). DO NOT use a sharp implement as dam-
age to the element surface could be caused. Ensure
sealing surfaces are clean and seals are undamaged, if
in doubt fit a new gasket.
Replace immersion heater(s) ensuring the lower (right
angled) element hangs vertically downwards towards
the base of the unit. It may be helpful to support the
immersion heater using a round bladed screwdriver
inserted into one of the thermostat pockets whilst the
backnut is tightened. Replace thermostat (Direct mod-
els) and thermostat capillaries into pocket (Indirect
models), rewire, check, close and secure immersion
heater housing cover(s).
7.5 EXPANSION VESSEL CHARGE PRESSURE
Remove the dust cap on top of the vessel. Check the
charge pressure using a tyre pressure gauge. The pres-
sure (with system de-pressurised) should be 3.5bar. If
it is lower than the required setting it should be re-
charged using a tyre pump (Schrader valve type). DO
NOT OVER CHARGE. Re-check the pressure and
when correct replace the dust cap.
7.6 RE-COMMISSIONING
Check all electrical and plumbing connections are se-
cure. Close the drain cock. With a hot tap open, turn
on the cold water supply and allow unit to refill. DO
NOT switch on the immersion heater(s) or boiler un-
til the unit is full. When water flows from the hot tap
allow to flow for a short while to purge air and flush
through any disturbed particles. Close hot tap and then
open successive hot taps in system to purge any air.
When completely full and purged check system for
leaks. The heating source (immersion heater(s) or
boiler) can then be switched on.
7.7 BENCHMARK
TM
LOG BOOK
On completion of any maintenance or service of the
Heatstore HSU the Benchmark
TM
“Installation, Com-
missioning and Service Record Log Book” should be
filled in to record the actions taken and the date the
work was undertaken.
7.3 STRAINER
Turn off the cold water supply, boiler and immersion
heaters. The lowest hot water tap should then be
opened to de-pressurise the system. Remove the Pres-
sure Reducing Valve cartridge by unscrewing from
the Pressure Reducing Valve Housing. The strainer
will be withdrawn with the Pressure Reducing Valve
cartridge. Wash any particulate matter from the strainer
under clean water. Re-assemble ensuring the seal is
correctly fitted, DO NOT use any other type of seal-
ant.
7.4 DESCALING IMMERSION HEATER(S)
Before removing the immersion heater(s) the unit must
be drained.
Ensure the water and electrical supply
and boiler are OFF before draining
. Attach a
hosepipe to the drain cock having sufficient length to
take water to a suitable discharge point below the level
of the unit. Open a hot tap close to the unit and open
drain cock to drain unit.
Direct models:
Open the cover(s) to the immersion heater housing(s)
and disconnect wiring from the thermostat mounted
on top of the immersion heater(s). Remove the ther-
mostat by carefully pulling outwards from the immer-
sion heater. Unscrew immersion heater backnut(s) and
remove immersion heater from the unit. A key spanner
is supplied with the Heatstore HSU unit for easy re-
moval/tightening of the immersion heater(s). Over time
the immersion heater gasket may become stuck to the
mating surface. To break the seal insert a round bladed
screwdriver into one of the pockets on the immersion
heater and gently lever up and down.
7.0 MAINTENANCE
7.1 MAINTENANCE REQUIREMENTS
Unvented hot water systems have a continuing main-
tenance requirement in order to ensure safe working
and optimum performance. It is essential that the Re-
lief Valve(s) are periodically inspected and manually
opened to ensure no blockage has occurred in the
valves or discharge pipework. Similarly cleaning of
the strainer element and replacement of the air in the
Expansion Vessel will help to prevent possible opera-
tional faults.
The maintenance checks described below should be
performed by a competent installer on a regular basis,
e.g. annually to coincide with boiler maintenance.
7.2 SAFETY VALVE OPERATION
Manually operate the Temperature/Pressure Relief
Valve for a few seconds. Check water is discharged
and that it flows freely through the tundish and dis-
charge pipework. Check valve reseats correctly when
released.
NOTE: Water discharged may be very
hot!
Repeat the above procedure for the Expansion Valve.
Indirect models:
Open the cover(s) to the immersion heater housing(s)
and disconnect wiring from the thermostat mounted
on top of the immersion heater(s). Remove the ther-
mostat by carefully pulling outwards from the immer-
sion heater. Remove capillary sensors from the pock-
ets on the immersion heater. Unscrew immersion heater
backnut(s) and remove immersion heater from the unit.
A key spanner is supplied with the Heatstore HSU
unit for easy removal/tightening of the immersion
heater(s). Over time the immersion heater gasket may
become stuck to the mating surface. To break the seal
insert a round bladed screwdriver into one of the pock-
ets on the immersion heater and gently lever up and
down.
