Precharge Pressure; System Check - Grundfos GT-H 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 frame when securing the
GT tank.
Fig. 4 Example of floor installation
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
Bracket
Wall
GT 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.
The precharge pressure 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
Adjustment of precharge pressure
If the precharge pressure is not suitable for the
application, it should be adjusted according to these
recommendations:
1. Use a suitable pressure gauge to check the
precharge pressure.
2. Release or add nitrogen as required to make the
precharge pressure equal to the recommended
precharge pressure.

4.4 System check

The GT tank must be by-passed if the system
pressure exceeds the maximum operating pressure
of the GT tank during a system check.
0.7 x setpoint
Setpoint
Variable speed
7