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9. Maintenance
9.1 General
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.
9.2 Standard inspection & maintenance
operations
Inspection
The immersion heater boss can be used as an access
for inspecting the water heater internally.
Safety valve operation
CAUTION
Water discharged may be very hot!
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.
`
Repeat the above procedure for the Expansion
`
Relief Valve.
Strainer
Turn off the cold water supply and power supply.
`
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.
1
2
3
Figure 9: Pressure Reducing Valve assembly
Item
1
Pressure Reducing Cartridge
2
3
Pressure Reducing Valve body
Table 7: Pressure Reducing Valve parts
Description
Strainer mesh
17
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