Help: Replacing Grundfos UP25-64F[email protected] Registered Users Posts: 7
Thanks in advance for any help or ideas.

Background info.
Single story house in S. Cal
2 solar water collectors on roof
C-30 Differential Temperature Controller (circa 1981)
Grundfos UP25-64F pump, #52722322. (also circa 1981)
Purpose for the pump is circulation of water between the panels and the solar collection tank.

I am preparing for the day when my pump goes out.

The current pump is a single speed. I would understand that the differential controller is also an 'off-on' device and is unable to vary the output voltage.

Grundfos Corporate recommends the replacement for the UP25-64F to be
UPS 15-55SFC, a variable speed pump. This does not make sense to me.

Does anyone have a recommendation for a replacement pump?



  • Dave AngeliniDave Angelini Solar Expert Posts: 6,384 ✭✭✭✭✭
    Re: Help: Replacing Grundfos UP25-64F

    What is the application? Open loop/closed? Drainback? Will they rebuild the pump or is it not supported?
    "we go where power lines don't" Sierra Nevada mountain area
    E-mail [email protected]

  • LucManLucMan Solar Expert Posts: 223 ✭✭✭
    Re: Help: Replacing Grundfos UP25-64F

    The ups 15-55 pump that they gave you is a good matchup to the original, just a 3 speed version selectable with an external switch. Use it on high speed to match the curve of the original pump, your existing diff. controller can still be used with no problem.
    This is a stainless steel open system pump.
    Just pull out the plastic check valve in the discharge end to get maximum flow and to allow drainback of collector fluid if you have a drainback system.
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