Tank Precharge Pressure; Setting Procedure; Start-Up; Maintenance - Grundfos Hydro Dome CHV 2-50 Installation And Operating Instructions Manual

6.3 Tank precharge pressure

The precharge pressure of the diaphragm tank (or bladder tank)
should be set to 0.9 x lowest cut-in pressure. See recommended
precharge pressure in section 6.2 when the factory settings of the
pressure switches are used.

6.4 Setting procedure

To change the factory settings, proceed as follows:
1. Open the discharge valves between pumps and manifold
(pos. 4, fig. 7).
2. Open the valves on the suction side (pos. 9, fig. 7).
3. Open the valves between discharge manifold and
diaphragm tank (pos. 5, fig. 7).
4. Close all taps on the discharge side, start the pumps and
note the pressure at zero flow (p
5. Pressure switch, Pr 1 (pos. 12, fig. 7):
5.1. Calculate the cut-out pressure:
Cut-out pressure, Pr 1 = p
5.2. Calculate the cut-in pressure:
Cut-in pressure, Pr 1 = cut-out pressure, Pr 1 - 1.5 bar.
Note:
- Δp < 1.5 bar decreases the drawdown volume of the tank
and increases the number of starts/stops per hour.
- Δp > 1.5 bar makes it uncomfortable for the user.
6. Pressure switch, Pr 2 (pos. 11, fig. 7):
6.1. Calculate the cut-out pressure:
Cut-out pressure, Pr 2 = cut-out pressure, Pr 1 - 0.3 up to
0.5 bar.
6.2. Calculate the cut-in pressure:
Cut-in pressure, Pr 2 = cut-out pressure, Pr 2 - 1.5 bar.
Note:
- Δp < 1.5 bar decreases the drawdown volume of the tank
and increases the number of starts/stops per hour.
- Δp > 1.5 bar makes it uncomfortable for the user.
7. Calculate the tank precharge pressure:
Precharge pressure = 0.9 x cut-in pressure, Pr 2 [bar].
Note:
The maximum precharge pressure can be limited,
depending on type of tank.
8. Stop the pumps, open the taps on the discharge side and
drain the pipes, pumps and tank (making the discharge
pressure = 0).
9. Set the calculated tank precharge pressure.
10. Cut-out pressure settings:
10.1. Start the pumps in automatic operation. When the
maximum pressure (Pr 1) is reached, the pumps will stop
automatically.
10.2. Adjust the cut-out pressures if they are not at the desired
levels (pos. 1, fig. 6).
10.3. Open the drain valve (pos. 8, fig. 7) until both pumps start.
Close the drain valve. When the new maximum pressure is
reached the pumps will stop automatically.
10.4. Repeat from point 10.2 until the desired cut-out pressures
are obtained.
11. Cut-in pressure settings:
11.1. Start the pumps in automatic operation. When the
maximum pressure (Pr 1) is reached, the pumps will stop
automatically.
11.2. Open the drain valve (pos. 8, fig. 7) and note the cut-in
pressures. Close the drain valve.
11.3. Adjust the cut-in pressures if they are not at the desired
levels (pos. 2, fig. 6).
11.4. Repeat from point 11.2 until the desired cut-in pressures
are obtained.
12. Perform a final test to make sure that the cut-in and cut-out
pressures are correct.
10
[bar]).
max
- 0.3 up to 0.5 bar.
max

7. Start-up

To start up a Hydro Dome booster set, proceed as follows:
1. Connect water and electricity supplies.
2. Check that the tank precharge pressure is equal to 0.9 x cut-
in pressure, Pr 2.
3. Close the pump discharge valves, prime the booster set and
the suction pipe.
4. Check that the settings have been carried out according to
section 6.
5. Three-phase versions only: Set the automatic circuit
breaker to the rated current stated on the motor nameplate.
6. Switch on the power supply, i.e. main switch, automatic circuit
breaker, etc.
7. Start the first pump.
8. Three-phase versions only: Check the direction of rotation
of the pump. In case of incorrect rotation, interchange two
phases of the power supply.
9. Vent the pump by slowly opening its discharge valve.
10. Repeat from point 6. for the other pump.
11. Release the booster set for operation by pushing both
selector switches into position "I".
The Hydro Dome is now ready for operation.

8. Maintenance

8.1 Maintenance of booster set

See installation and operating instructions for CHV pumps.

8.2 Maintenance of CS 201 and CS 203b

The CS 201 and CS 203b controllers are maintenance-free.

8.3 Checking the precharge pressure

To ensure reliable and correct operation, including the frequency
of starts and stops, the precharge pressure of the diaphragm tank
(or bladder tank) should be checked regularly (at least once a
year).