8
7.0 MAINTENANCE - SAFETY VALVES
The Temperature/Pressure Relief Valve and, if fitted, the Pressure (Expansion) Relief
Valve should be regularly checked. Manually operate the valves by either twisting the
cap or lifting the lever. Ensure water flows freely from the valve(s) and through the
discharge pipes. Ensure the valve(s) reseat correctly when released.
8.0 MAINTENANCE -
EXPANSION VESSEL PRECHARGE PRESSURE
The Expansion Vessel, if fitted, should have a precharge pressure of 4.1 bar (60 p.s.i.).
This can reduce over time and eventually require re-charging. To do this:
8.1
Turn off water supply to the unit; open a hot tap to relieve system pressure.
8.2
Remove dust cap from top of Expansion Vessel
8.3
Check pre-charge pressure using a tyre pressure gauge. If the pressure is lower
than 4.1 bar (60 p.s.i.) it should be recharged using a tyre pump (Schraeder Valve
type). DO NOT OVER CHARGE.
8.4
Re-check pressure and when correct replace dust cap.
8.5
Turn on mains water supply and close hot tap.
INLET
OUTLET
(NOT SHOWING
T&P VALVE)
CABLE CLAMP
EARTH POST
COMBINED THERMOSTAT
AND THERMAL CUT-OUT
FIGURE 6: CORRECT ORIENTATION OF ELEMENT PLATE ( VIEWED FROM TOP OF UNIT ).
