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GRUNDFOS pump noise

Zuki1
Zuki1 Member Posts: 8
edited December 2023 in Radiant Heating
It’s our first year in this house and it has a couple of GRUNDFOS pumps. The one on our crawl space seems to be making an odd noise, almost like a rubbing but it is not consistent. I have uploaded a video here

https://youtube.com/shorts/8jo4avPJv84?si=LPi5txW3Ud2y8cil

hopefully the video works. The sound isn’t as loud as the video makes it out to be. The hum is from a relay they is just out of the video.Just trying to figure out how I should go about fixing it. 

Thanks,

Larry 

Comments

  • Larry Weingarten
    Larry Weingarten Member Posts: 3,599
    Hi, Is the shaft of the motor in a horizontal position? If not, there may be air trapped in the pump. How hot is the pump? Should be very roughly the same temperature as the pumped fluid. If it's much hotter, the fluid isn't moving through enough to cool the pump.

    Yours, Larry ;)
  • Zuki1
    Zuki1 Member Posts: 8
    The shaft is horizontal. The pump seems
    to be about the same temp as
    the water. Thanks for asking 
  • hot_rod
    hot_rod Member Posts: 23,400
    Try loosening that screw a bit on the end to purge any air out of the shaft.
    What is the pump used for?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Zuki1
    Zuki1 Member Posts: 8
    It’s for the radiant floor heat in the house. The boiler is out on the shop. I’ll see if there is any air.
  • Zuki1
    Zuki1 Member Posts: 8
    Very little water came out. When I have time, I’ll pull the cartridge out and inspect it. 
    Maybe there is dirt/sediment around the impeller? I’ll order a replacement cartridge to have on hand in case this one is bad.
  • HomerJSmith
    HomerJSmith Member Posts: 2,635
    edited December 2023
    There ain't no cartridge in a Grundfos pump. Sound like the pump is running dry. Remove the screw on the end of the pump with a screwdriver and see if water comes out. That is an old pump and may be worn bearings.
  • hot_rod
    hot_rod Member Posts: 23,400
    If not you have valves on both sides, screwdriver slots. Turn then 1/4 turn, then remove 4 allen bolts to remove pump motor and impeller from the body. Stones, pipe chips, etc can get into the impellers sometimes.nu
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    HomerJSmithZuki1
  • JDHW
    JDHW Member Posts: 81
    If you are going to remove the motor from the body then spin the body through 180 degrees when you re-assemble. This stops water getting into the electrical connections of there is a leak.
    Zuki1
  • HVACNUT
    HVACNUT Member Posts: 6,334
    Zuki1 said:
    I’ll order a replacement cartridge to have on hand in case this one is bad.
    It's usually cheaper to order the complete circulator. 
    It's got isolation valves so changing the whole thing is just as easy.
    And like @JDHW said, put the electric on top.
    Zuki1
  • Zuki1
    Zuki1 Member Posts: 8
    I ended up replacing the cartridge. Cost was under half of a new pump. It is quieter now. I also rotated the body so wiring was on top.
    Thanks for all the replies.

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