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Circulator noise

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HAB
HAB Member Posts: 11
in THE MAIN WALL
I recently installed a Bell&Gossett NRF-36 circulator on our boiler. It was very quiet to start but is now getting noisy. It is a liquid cooled pump and gets pretty hot. I am using antifreeze in the system. Any ideas what is causing noise?
Thanks.

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  • Larry Weingarten
    Larry Weingarten Member Posts: 3,304
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    Hello, A basic question; is it installed with the shaft horizontal? I'm wondering about air causing problems. :/

    Yours, Larry
  • hot_rod
    hot_rod Member Posts: 22,157
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    That's a fairly high head circulator, they can be more prone to cavitation. What is the applications?

    Also, glycol is a tough fluid to get all the air out of, does it have a good, properly installed air seperator?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • HAB
    HAB Member Posts: 11
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    the pump shaft is horizontal. There is a B&G air vent. No air seperator. Running the pump on lowest speed. This replaced a B&G series 100 circulator. Never heard a noise like this with old pump even with some air in system.
  • HVACNUT
    HVACNUT Member Posts: 5,841
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    You probably introduced air into the system when you replaced the circ.
    Seems like it needs to be purged, but with antifreeze you must recirculate with a transfer pump.
  • hot_rod
    hot_rod Member Posts: 22,157
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    HAB said:

    the pump shaft is horizontal. There is a B&G air vent. No air seperator. Running the pump on lowest speed. This replaced a B&G series 100 circulator. Never heard a noise like this with old pump even with some air in system.


    I don't think that NRF-36 is a good replacement for a series 100 B&G. If the series 100 was doing the job, it should be replaced with a similarly sized circulator. The pump curves hold the answer to the correct selection.


    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    kcopp
  • Tinman
    Tinman Member Posts: 2,808
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    Hot Rod is right. The NRF-36 is a high head pump. The 100 is a very low head pump, flat curve. B&G NRF-33, Taco 0010 would be good choices.
    Steve Minnich
  • HAB
    HAB Member Posts: 11
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    I have had problems with B@G 100 pumps. I have replaced them twice in the in the last twenty years. On the last one the springs on coupler ate through the drive arms. I replaced the drive but it did not sound right. probably because I had no way to align the shafts. In the time we had the last one on we converted a garage on the other end of the house to a large living area. This added quite a bit of head to the system. Since I was changing pumps anyway the calculations suggested a higher head pump and I wanted to go with a direct drive pump. That is why I changed to this pump. I will purge the system and after heating system is over install a air seperator.
    The system will be 40 years old soon and it is probably time to upgrade to a more energy effiecent model.

  • HAB
    HAB Member Posts: 11
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    I have had problems with B@G 100 pumps. I have replaced them twice in the in the last twenty years. On the last one the springs on coupler ate through the drive arms. I replaced the drive but it did not sound right. probably because I had no way to align the shafts. In the time we had the last one on we converted a garage on the other end of the house to a large living area. This added quite a bit of head to the system. Since I was changing pumps anyway the calculations suggested a higher head pump and I wanted to go with a direct drive pump. That is why I changed to this pump. I will purge the system and after heating system is over install a air seperator.
    The system will be 40 years old soon and it is probably time to upgrade to a more energy effiecent model.

  • icy78
    icy78 Member Posts: 404
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    I can see it adding load, but why did it add "quite a bit of head"?
  • Drewby
    Drewby Member Posts: 2
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    Possible solder in volute?
  • Jamie Hall
    Jamie Hall Member Posts: 23,322
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    icy78 said:

    I can see it adding load, but why did it add "quite a bit of head"?

    This strikes me as possibly part of the problem. Unless the radiation in the new addition was added in series with the original -- which it shouldn't have been -- there should have been very little head change. There may have been -- probably was -- a significant flow change. The two are not interchangeable!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Bob_51
    Bob_51 Member Posts: 6
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    It may be too much work, but now that you have already installed it, and it can't be returned, you can look at installing the expansion tank, feed line(or glycol feed tank) somewhere into the suction side of the pump. that should keep your pressure high enough to prevent cavitation. if it is already done that way, then verify your make up pressure is what you need for your application.
    Good luck!
    Bob

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