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15-58 bleed screw

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EYoder
EYoder Member Posts: 60
Just wondering, I'm seeing some Grundfos 15-58 circs with bleed screws and some without. Both are new in box. Are they making them both ways?
Thanks!

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  • hot_rod
    hot_rod Member Posts: 22,144
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    And sometimes if you pop off the plastic nomenclature cover, there is an end shaft screw slot plug hiding beneath.

    The exposed end caps seem to come and go?

    The date of manufacture used to be listed on the data plate, week and year, check and see if some are older inventory.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • GroundUp
    GroundUp Member Posts: 1,907
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    They seem to be hit and miss. I buy 4-5 dozen 15-58 a year and they hop back and forth. Never found a rhyme or reason myself
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,003
    edited August 2019
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    I like the slotted screw; helps when you want to make sure the shaft is turning and sometimes for eliminating air when it's stuck inside the pump.

    But has Grundfos ever listened to me?
    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
  • hot_rod
    hot_rod Member Posts: 22,144
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    I like the slotted screw; helps when you want to make sure the shaft is turning and sometimes for eliminating air when it's stuck inside the pump.

    But has Grundfos ever listened to me?

    One unsubstantiated rumor I heard was concern about liability if someone opens that screw and gets a blast of steam in the face, or elsewhere?

    Having it under a cover where a DIYer is less apt to "screw" with it is maybe a good compromise?

    I've certainly experienced that with an air locked wet rotor circulator.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • EYoder
    EYoder Member Posts: 60
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    Thanks a lot for the info. Seems odd they're made both ways. Weird.
  • Tinman
    Tinman Member Posts: 2,808
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    Every 15-58 that I’ve installed or pulled did not have the screw. Loved it on the 15-42s though. I’m not sure why I keep so many used pumps? I’m not a contractor.
    Steve Minnich
  • Lance
    Lance Member Posts: 270
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    I am confused between the use of terms here, bleed vs. shaft screws. I am only aware of the fact the many very low Horse Power 115v pumps had very little torque and the shaft screw was used to free up a stuck shaft from sitting over the summer. Than came a capacitor which helped. But this is engineering to solve a problem discovered.
  • GroundUp
    GroundUp Member Posts: 1,907
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    @Lance some of the Grundfos circs have a small SS screw/plug in the end of the case opposite the volute that both helps to bleed air and can be removed to verify the shaft is spinning (or not) as it's directly beyond the end of the shaft. I have also used it to push start a sticky circ after sitting many years, just poke a pick in the hole and give it a little push