Pressure Tank/Pressure Relief Valve/Low Pressure
To maintain constant pressure and prevent frequent startup, a small-capacity pressure tank is need-
ed in the system (refer to the minimum capacity of pressure tank table below). The VARIOspeed
®
MICRO VFD may use a pressure tank of a larger capacity than listed on the table blow.
Minimum Capacity of Pressure Tank
Flow Rate (GPM)
Tank Size
(Total Capacity)
Less than 12.0
4 Gallons
More than 12.0
8 Gallons
Pre-Charge Pressure
1. Initial charge pressure should be at least 70% of the system pressure (Set pressure).
2. To maintain the optimum pressure level, check the air pressure in the tank regularly.
Set Pressure (PSI)
Initial Charging
Pressure (PSI)
50 (default)
35
55
39
60
42
65
46
A Pressure Relief Valve Must be Installed.
A pressure relief valve
MUST
be installed as close as possible to the pump discharge and plumbed
to a drain able to handle the full flow of the pump in the event of a malfunction.
WARNING!
Failure to use a pressure relief valve could result in burst pipes and flooding if a system failure should occur.
Low Pressure Switch Shutdown (optional)
A pressure switch may be used to shut down the pump on low pressure. This switch will open on low
pressure and stop the pump from operating with insufficient water supply. (See pg 12 for electrical
connections.)
SJE-Rhombus
®
VARIOspeed
®
Micro Controller User Manual
7
