Section 7: maintenance
Page 28
7.1 SErVicinG And mAintEnAncE
1. Servicing and maintenance must only be carried out by
a competent unvented hot water installer, or by Grant
Engineering (UK) Limited authorised personnel.
2. Before any work whatsoever is carried out on the installation,
it MUST first be isolated from the electricity supply.
! WArninG !
Both the primary and secondary systems will contain very
hot water that will scald; therefore care should be taken
when opening any joints, seals or valves.
3. Only use spare parts authorised by Grant Engineering (UK)
Limited. The use of unauthorised spare parts will invalidate
the guarantee.
4. Drain the cylinder – When draining the cylinder, always
switch off the boiler and the immersion heater first. Turn off
the water supply at the service valve or mains stopcock.
Connect a hose pipe to the drain cock (see Figures 2-3 or
2-4) and route it to a convenient gully. Open the drain cock
and all hot taps that are served by the cylinder. The cylinder
may take several minutes to empty completely.
5.
In hard water areas it may be necessary from time to time to
remove and de-scale the immersion heater element. Replace
the gasket each time it is removed.
6. Remove the cartridge from the pressure-reducing valve
(PRV). Check the strainer and if necessary remove any
debris from in front of it.
Replace the cartridge. Refer to Section 7.3 (Pressure
Reducing Valve).
7. Remove the expansion relief valve cartridge. Check and
clean valve seat. Replace cartridge. Refer to Section 7.4
(Expansion Relief Valve Cartridge).
8. Check the charge pressure in the expansion vessel and top
up as necessary. The charge pressure should be 3.0 bar.
Refer to section 7.5 (Expansion Vessel).
9. Whilst the hose pipe is connected, the drain cock open and
with the immersion heater removed, the cylinder may be
flushed out to remove any debris, sand or lime scale particles
that may have collected in the bottom by using a further hose
pipe connected to the cold water main.
10.
Close the drain cock, disconnect the hose, refit the
immersion heater and close all hot water taps before re-
opening the stopcock. Allow the cylinder time to fill whilst
checking for any leaks. Release any air from the system by
opening each hot water tap individually, starting with the one
furthest from the cylinder.
11. Manually lift the expansion relief and temperature and
pressure relief valve one at a time, every 12 months (more
frequently in hard water areas) to prevent debris from
building up behind the valve seat. Whilst carrying out this
operation, check that the discharge to waste is unobstructed.
Check that each valve seals correctly when released.
As the valves are pre-calibrated, they require no further
maintenance.
12. Finally switch on the mains electricity supply to the immersion
heater and the boiler. As the system heats up, check again
for any leaks and rectify as necessary.
7.2 inLEt mAnifoLd ASSEmBLY
The inlet manifold assembly should not, under normal
circumstance, require any maintenance. During annual servicing
it may be necessary to inspect and/or clean the line strainer,
the pressure reducing valve cartridge, expansion relief valve
cartridge. The frequency of cleaning will depend on the local
water conditions.
7.3 PrESSUrE rEdUcinG VALVE
1. Isolate the cold water supply.
2. Unscrew the retaining nut of the valve. The complete
operating mechanism, including the strainer can be removed.
3.
Clean the filter mesh and the cartridge under running water.
4. Replace cartridge ensuring that strainer is correctly located
and reassemble the unit.
Pressure Reducing Valve cartridge and strainer (Grant UK
product code: GCS07C) - 3.0 bar.
7.4 ExPAnSion rELiEf VALVE
cArtridGE
1. Isolate the cold water supply.
2. Remove grub screw (Allen Key type) from body of valve and
withdraw valve ensuring not to damage o-ring.
3. Clean valve seat face and seating - do not scratch or
damage either seat face or seating.
4.
Refit in reverse order. Do not overtighten.
Expansion valve cartridge (Grant UK product code: GCS08).
7.5 ExPAnSion VESSEL
1. Isolate the cold water supply.
2. Open hot water taps.
3.
Drain cylinder to below the expansion vessel flexible hose
connection.
4. Check expansion vessel air charge.
5.
Replace expansion vessel if necessary.
6.
Close drain off cock and turn on cold water supply.
7.
Refill cylinder whilst checking for leaks.
8.
When water is flowing freely from taps close taps.
7 mAintEnAncE