10
To maintain optimum performance of the system, a pressure differential of approx. 1.5 Bar
between the mains water static pressure and air precharge pressure within the vessel should
be maintained. The air precharge of the vessel should never be less than 0.5 Bar.
-
Pumped units
have the air precharge pressure set at the factory to 1.5 Bar/21.75PSI.
This will deliver optimum performance for the pumped units. The actual air precharge
pressure may vary due to storage conditions and the length of time in storage. The air
precharge pressure should be checked and adjusted if necessary.
-
Unpumped units
require the incoming mains water static pressure (when no outlets are
drawing water) to be measured and the air precharge in the vessel adjusted accordingly.
Refer to the following steps and Table 1.
Checking air precharge pressure
:
- Before checking the air precharge pressure of the vessel make sure that the electrical
supply to the pump has been isolated (for pumped versions), the mains water supply to the
unit has been switched off via the stopcock, all water has been emptied from the vessel
and that an outlet such as a tap is left open to allow any residual water to escape.
- Fully unscrew and remove the valve cover located on the top of the pressure vessel to
expose the Schrader air valve.
- Using a tyre pressure gauge, check the air pressure within the vessel.
6.5 Air precharge pressure of the vessel
Valve cover
Schrader
air valve
Figure 8