HAMWORTHY HEATING LTD
10
WEYMOUTH
500001112/C
7.6 Filling The Unit
1) Check all connections and pressures. Open inlet isolation valve and fill the tank.
2) Undo the priming screw on pump head (fig 15). Prime until water appears. Close the screw and turn on the
pump (keeping system isolation valve closed). Pump should run for a few seconds until set pressure is reached.
Figure 15a. Priming Screw Standard
Figure 15b. Priming Screw Advanced
3) Check for any leaks within the unit, if OK open system isolation valve and fill system via filling loop.
4) The unit will now monitor the system and keep it at the required pressure.
7.7 Pressure Switch Adjustment
The pressure switches are fitted with a scale to indicate the pressure at which they are set. This scale is to be
used for indication only. As all the pressure switches and the pressure gauge take readings from the same place,
the unit’s pressure gauge can be used to give an accurate reading when setting switching levels .
The switches should be set last, after all the other commissioning tasks are complete.
Figure 16. Pressure Switch Adjustment
All the pressure switches have a nominal pressure differential (Hysterisis) of 0.4 bar. This means that there will
be 0.4 bar between the pressure at which the switch changes state during a pressure rise and the pressure at
which it will change when the pressure is falling again or vice versa. For example if the cold fill pressure switch is
set to 3.4 bar then the switch will operate when the pressure rises to 3.4 bar causing the pump to stop. The switch
will not change over & start the pump until the pressure has fallen back to 3.0 bar.
