On two pump units the duty pump will automatically rotate each time the pump set starts.
If the duty pump fails to make pressure the standby pump will automatically take over from the duty pump,
and that pump will then be locked out until a manual reset has taken place by switching the auto/manual
selector switch to the off then back to auto position.
Pressure reducing valve setting
The pressure reducing valve has been factory set to 1 bar if this setting needs adjusting, turn the adjusting
screw situated at the top of valve clockwise to increase pressure or anticlockwise to decrease pressure.
The system pressure can be observed on the adjacent pressure gauge. When reducing pressure to the
system it will be necessary to drain some water from the system to relieve pressure in the system, so the
true pressure can be seen on the gauge.
Pump test (two pump units only)
Each pump can be manually tested by switching the rotary switch to either P1 manual or
P2 manual position the selected pump will then run irrespective of the system pressure.
Warning: Under no circumstances should a pump be left running in the manual position.
Boiler/chiller interlock (When fitted)
A volt free normally closed circuit is provided as a boiler/chiller interlock. The circuit has 1 high pressure con-
tact and 1 low pressure contact either of which, when operating, will open the boiler/chiller circuit. If the high
pressure contact is not required with chiller applications it can be omitted. See product wiring drawing.
Pressure switch settings
Pump control
The pump control pressure switches have been factory set and should not need any further adjustment.
High/low pressure switch setting
The Low pressure switch can be adjusted as follows, providing the PRV has been set as described the set
should now be sitting with the correct fill pressure.
The low pressure switch should now be adjusted to approximately 0.35 bar below the fill pressure.
Isolate the power supply to both the pressurisation unit and the boiler/chiller circuit.
Isolate the pressurisation unit from the system by closing the discharge isolation valve.
Slowly release pressure in the pressurisation unit by opening the drain valve.
Observe the pressure on the PRV pressure gauge, when pressure drops to 0.35 bar below the system set
point close the drain valve.
Connect a continuity tester between the common and normally closed tags. Turn the adjusting nut until the
electrical circuit just opens. Note a quarter turn represents approximately 0.55 bar.
Switch power supply to unit back on and let the pumps recharge the unit (do not open the discharge valve).
Switch off power supply again and slowly release pressure and observe the point at which the switch
operates, adjust as required. Open discharge valve to system and reconnect power supplies.
The High pressure set point should be adjusted after the system is at operating temperature.
Isolate the power supplies to both pressurisation unit and boiler/chiller controls.
Connect a continuity tester between the common and normally closed tags. Turn the adjusting nut until the
electrical circuit just opens then re-adjust the setting approximately 0.2 bar higher turning the adjusting nut
anti-clockwise slightly. Note a quarter turn represents approximately 0.55 bar.
Re check the setting by charging the system via the quick fill connection until the circuit opens. When
satisfied with the setting, drain off water via the drain valve until the system returns to normal fill pressure.
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presfix alpha REV B o and m instructions:Layout 1
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