Franklin 5870206300 installation manual Pressure Tank, Minimum Tank Size

Pressure Tank

The SubDrive needs only a small pressure tank to maintain constant pressure (see table below for recommended tank size). For pumps rated 12 gpm or more, a slightly larger tank is recommended for optimum pressure regulation. The SubDrive can also use an existing tank with a much larger capacity.

Table 3: Minimum Pressure Tank Size (Total Capacity)

Pump Flow Rating

Less than 12 gpm 12 gpm and higher

Controller Model

SubDrive300

SubDrive300

Minimum Tank Size

8gallon

20gallon

The pressure tank pre-charge setting should be 70% of the system pressure sensor setting as indicated in the following table.

Table 4: Pressure Tank Precharge (PSI)

System Pressure	Pressure Tank
(at Pressure Sensor)	Setting (±2 psi)

25

30

35

40

45

50

55

60

65

70

75

80

18

21

25

28

32

35Factory Setting

NOTE: Check tank precharge regularly to maintain optimum pressure regulation.

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