Precharge Pressure - Grundfos GT-CF Installation And Operating Instructions Manual

Floor installation
Large GT tanks must be secured to the floor by
means of bolts. Use bolts, washers and nuts that are
suitable for the surface of the floor or base frame.
Use all bolt holes in the base frame when securing
the GT tank.
Tanks with steel bases should be mounted using the
brackets supplied, while tanks with plastic bases
should be mounted through the bolt holes in the
base. For bases without bolt holes, drill four holes at
equal distance in the rim of the base.
Fig. 3 Installation of tank with steel base
Fig. 4 Installation of tank with plastic base
Wall installation
Small GT tanks up to 33 litres must be secured to a
wall or similar.
Fig. 5 Example of wall installation with wall
bracket
4
Bracket
Tank

4.3 Precharge pressure

The GT tanks are supplied from factory with a
precharge pressure. See tank nameplate.
The precharge pressure must be adjusted according
to the actual application and the installed pump.
It should be slightly below the pump cut-in setting.
Recommended precharge pressures:
• 0.9 x setpoint for fixed-speed pumps
• 0.7 x setpoint for variable-speed pumps.
0.9 x setpoint
Setpoint
Fixed speed
Fig. 6 Precharge pressure
4.3.1 Adjusting the precharge pressure
Warning
Before starting work on the product, make
sure there is no system pressure on the
tank.
Disconnect pumps or switch off the power
supply.
If the precharge pressure is not suitable for the
application, adjust it as follows:
1. Switch off the pump. Open the nearest tap to
make sure that no system pressure is affecting
the reading.
2. Remove the protective cap.
3. Check the precharge pressure with a suitable
pressure gauge.
4. Release or add air as required to make the
precharge pressure equal to the recommended
precharge pressure.
5. Fit the protective cap to prevent air from
escaping from the tank.
Never exceed the maximum operating
Caution
pressure of the tank.
0.7 x setpoint
Setpoint
Variable speed