14
MAINTENANCE
MAINTENANCE REQUIREMENTS
Unvented hot water systems have a continuing
maintenance requirement in order to ensure safe
working and optimum performance. It is essential
that the relief 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 operational faults.
The maintenance checks described below should be
performed by a competent person on a regular basis,
e.g. annually to coincide with boiler maintenance.
After any maintenance, please complete the
relevant Service Interval Record section of the
Benchmark Checklist located on Page 19 and 20 of
this document.
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
discharge pipework. Check valve reseats correctly
when released.
NOTE: Water discharged may be
very hot!
Repeat the above procedure for the Expansion
Valve.
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
pressure reducing cartridge to access the strainer
mesh. 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
sealant.
DESCALING IMMERSION HEATER(S)
Before removing the immersion heater(s) the unit
must be drained.
Ensure the water, 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 UNITS
Switch on electrical supply to the immersion
heater(s) and allow the Potterton Gold to heat up to
normal working temperature (60ºC recommended,
approximately graduation 4 on the thermostat). If
necessary the temperature can be adjusted by in-
serting a flat bladed screwdriver in the adjustment
knob on top of the immersion heater thermostat
and rotating.
The adjustment range 1 to 5 represents a tempera-
ture range of 10
o
to 70
o
C. Check the operation of
thermostat(s) and that no water has issued from
the expansion relief valve or temperature/pressure
relief valve during the heating cycle.
IN
DIRECT UNITS
Open the cover(s) to the immersion heater housing(s)
and disconnect wiring from immersion heater(s)
thermostat(s). Remove thermostat by carefully pulling
outwards. Remove thermostat capillary sensors from
the pockets on the immersion heater. Unscrew
immersion heater backnut(s) and remove immersion
heater from the unit. A key spanner is supplied
with the POTTERTON GOLD cylinder 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 pockets
on the immersion heater and gently lever up and
down.
Carefully remove any scale from the surface of the
element(s). DO NOT use a sharp implement as
damage to the element surface could be caused.
Ensure sealing surfaces are clean and seals are
undamaged, if in doubt fit a new gasket
(part number 95 611 822).
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 capillaries into pocket. Replace the
immersion heater thermostat by carefully plugging
the two male spade terminations on the underside
of the thermostat head into the corresponding
terminations on the element. Rewire, check, close
and secure immersion heater housing cover(s).
EXPANSION VESSEL CHARGE PRESSURE
Remove the dust cap on top of the vessel. Check the
charge pressure using a tyre pressur
e gauge. The
pressure (with system de-pressurised) should be 3.5 bar.
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.
RE-COMMISSIONING
Check all electrical and plumbing connections are
secure. 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 until 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.