Below are some tips regarding steps missed when installing Magna 3 series pumps:


Use stranded wire only as instructed. Hard wire is rigid and occasionally when closing the faceplate after wiring, it can cause the plug-in module to become loose or pull out. If so, the low voltage alarm (error code 75) will appear, or the pump will not turn on.   

The pump must be powered on all the time with it enabled through the digital input.   Do not wire it any other way.

No need to run wires for setting up for lead-lag operation. Go to ASSIST menu and set up through Blue tooth.

Head Position

The faceplate must be in a horizontal position as facing the LCD screen. The reason for this is two-fold. There is a weep hole at the bottom to allow condensation to drain. Second, the heat fins work best when the head is horizontal.

Do not make the mistake of having the Grundfos name on top, it always should be vertical to the side.


There must be a check valve on the discharge. Because the ECM can run on such low power, having backflow can cause it to run even though there is no power to it.

Control Mode

The factory setting is AutoAdapt which is applicable for roughly 85% of heating applications.  If the system’s demand is high head/low flow or low head/high flow, change the control mode to Proportional Pressure and dial in the setpoint. (1’ of head equals 2.31 psi)

Best Practice

To enhance the system and provide ultimate protection to the sensors, install a Spirotherm VDT series air/dirt eliminator between the boiler and the pump.