SOLAR PML pump

don123

HI, im looking to replace a Grundfos solar PML 25-145 N 180. This pump is used for a drain back solar domestic water heating application. none of my suppliers could locate the pump. i'm located in Massachusetts. the solar setup is also connected to a caleffi solar isolar BX control. could anyone point me to where I could get the Grundfos solar PML 25-145 N 180 Pump. if not what other pump would be a match and also connect to the Caleffi controller. I can post pictures if needed. Is this pump supposed to communicate to the caleffi solar bx? this is a commercial application.

Thank You

hot_rod

that is an OEM pu p, built for a specific solar manufacturer. I have only seen them with union bodies and 230V Euro wire connections
is it being run from the I solar controller?

Look at the pump curve, perhaps find a US version that would fit that pump volute.

Or find replacements on the various UK sites if it needs to be the exact same pump.

If it is in a premade pump station you are tied to those large union connections, or build your own pump module with a standard off the shelf pump.

What is the height from where the drainback tanks located?

How many and what type panels.

I’m sure you can find a standard pump to do the job without sourcing an expensive OEM Alpha.

Yes pics, the piping and controller wiring.

The BX can operate a pump without using the PWM output

hot_rod

the second number is head in dm, decimeter, so that is145 decimeter to feet.

Example below.

If the control is speed modulation, it may never run that high up the curve.

So that is a high head circ for the initial lift, 145 dm is about 45’ of head

You may not need that much lift, so measure what you have and find a circ that fits the head.

The drainback modules Caleffi built for the U.S. were 15-100, small union. Although I think those have been discontinued. It was the largest 120V pump theResol controller could run with a1 A relay.caleffi 6

I would not worry about a yellow label solar pump, they were just a small bit higher temperature rating.

Here is an example of how you calculate head or lift head for a drainback, determine exactly what you have. You may have a seperatedrainback tank? Measure from that water level to the highest point in the collector.

The BX can also run two small circs for drainback. Start two until the siphon establishes, then turn off one. The one circ just circulates once the system fills. This is a good option for inexpensive drainback pump possibility. Ideally they would be stainless or bronze. I’ve always used basic cast iron pumps.

Where are you located? At higher elevations establishing a siphon with a high lift becomes tricky