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Grundfos Stainless Steel Pump

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I just replaced the motor on a DHW recirculating pump because it was making a loud squealing sound. The volute was in good shape. Could I have used the motor from a cast iron Grundfos pump?
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

Two btu per sq ft for degree difference for a slab

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  • hot_rod
    hot_rod Member Posts: 22,158
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    Same model number? I have swapped heads in the past like that.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Derheatmeister
    Derheatmeister Member Posts: 1,544
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    I just replaced the motor on a DHW recirculating pump because it was making a loud squealing sound. The volute was in good shape. Could I have used the motor from a cast iron Grundfos pump?

    What size was this circulating pump ....15 series or 26 series ?
    Generally if it is making a Squealing sound it is the cartridge that is in need of replacement !
    However... If we find that the ampdraw is less that half of the name plate rating the entire circ shoud be replaced in order to prevent Callbacks.
    And yes... The Cartridge/Heads on the Stainless and ferrous 15 series circs are the same.
    Just the volutes are make of Stainless or Cast iron.
    Alan (California Radiant) Forbes
  • Big Ed_4
    Big Ed_4 Member Posts: 2,785
    edited March 25
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    You should replaced the whole pump, it would be a better way to go.... Ask me how I know that :wink:

    There was an error rendering this rich post.

  • Dave H_2
    Dave H_2 Member Posts: 556
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    I am not sure, I haven't cut one open to inspect.

    I do know with Taco AC circs (not ECM), the cartridge manufacturing is specific to the system. The rotor is made up of steel plates for heating (closed loop) systems and circ that are not cast iron, the rotor gets a stainless steel cladding on the outside due to these circs being used in an open system.

    Yes, the motor and cartridge are interchangeable as they will fit up, but not interchangeable. Check with manufacturer
    Dave H
    Alan (California Radiant) Forbes
  • hot_rod
    hot_rod Member Posts: 22,158
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    I've put 15-29, 15-35, 15-42, 15-58, Alpha 15-55 in the same volute, they all fit and seal. Performance may be off a bid when you mix and match. Probably not factory authorized:)
    The 15-100 on the right takes a specific volute.
    I think all the 15 series have ceramic shafts?

    This assembly is from a cast 15-58, been installed for years, no rust.

    I think you mean motor with the cartridge and impeller from a cast circ 15-58 into a SS 15-58 volute, for example, to save some bucks?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream