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Which bearings for my DA tank pump?

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Rich_L
Rich_L Member Posts: 81
I have customer with two Grundfos multistack pumps feeding two Cleaver Brooks boilers from the DA tank. The bearings are going out in the pump stacks and I need to replace them. I gave my parts house the numbers off the pump and they're asking if I want bronze or ceramic bearings in my stacks. I told them I just want whatever the pump had before and they said it could have had either. Looking at the existing setup it looks like I have ceramic bushings but it's only lasted a couple of years and they're quite pricey! They didn't ask which ones I wanted last time by the way. Which ones should I put in there for this application? My DA tank runs about 170 to 190 degrees and the boiler is running at 60 PSI. Thank you for any help!

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  • kevinj_4
    kevinj_4 Member Posts: 91
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    We have found that rebuilding them gives a shorter life than new as the plates will give up next and the cost for a new bottom end is not much more money.

    As to bearing type the dealer should be able to get that from the build tag.
    Alan Welch
  • Rich_L
    Rich_L Member Posts: 81
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    Maybe I was unclear in my question. I'm not planning on replacing just the bearings but the entire stack (bottom end). That was my thought too on the pump tag but my dealer's saying it could be either. I don't see how that can be... I appreciate your response Kevin.
  • kevinj_4
    kevinj_4 Member Posts: 91
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    Well then if you give them all operating parameters they should set you up properly.

    If they can't you need a different dealer.

    You have them apart, can't you identify the bearing material?

    You are running your DA on the cold side, how much pressure on the DA?

    Most of the plants we service run about 220° on boilers under 150 psi.
  • Rich_L
    Rich_L Member Posts: 81
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    The material I have in there now appears to be ceramic but since it only lasted a couple of years I'm wondering if it should have been bronze? Very much agreed that the dealer should be able to set me up with the right material for the application. They just want to know what I have now so they can order the same. I'm wondering what it really should be! Thanks again for your help, Kevin.
  • kevinj_4
    kevinj_4 Member Posts: 91
    edited January 2018
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    Well, it has been my experience that 2 years is about it for this type of pump.

    We have used different brands and I guess when you think that 2 years is about 17,000 hours the life span looks a bit better.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,840
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    Call Grundfos and ask them which bearing they recommend will last longer in your application. guessing ceramic