Grundfoss circulation pump question

Discussion in 'Plumbing Forum' started by yelkenli, Jun 16, 2019.

Help Support House Repair Talk by donating:

  1. Jun 16, 2019 #1

    yelkenli

    yelkenli

    yelkenli

    New Member

    Joined:
    Apr 18, 2019
    Messages:
    4
    Likes Received:
    1
    Location:
    SC
    I have a UPS 15-55 SFC running in a residential hot water circulation system. The plumbing was drained for work and then refilled. When turning on the pump, three days after refill and air purge from the faucets, the grundfos seemed to work - I could hear water gurgling through and then (I thought) go quiet.

    After an hour of running, I found water was not circulating. I felt the housing of the pump and it was too hot to touch. I opened the nut and water came out - not air. There is also a small piece of white material floating in the water behind the nut. The shaft rotates freely. I cracked open the isolation valve and water also came from there - not air.
    The pump makes more noise than before, and I don’t think it is pumping.

    I am trying to figure out what happened (did I miss a recommissioning step), what is the status of the pump, and what needs to be done to fix it. Can you provide some thoughts and recommendations?
     
  2. Jun 16, 2019 #2

    Michael Armstrong

    Michael Armstrong

    Michael Armstrong

    Well-Known Member

    Joined:
    Jan 1, 2019
    Messages:
    66
    Likes Received:
    19
    Location:
    NW Washington
    Grundfos only says to make sure the suction side of the system is filled with water before operation, and it sounds like you did that. I wonder if a big slug of air got into the hot water tank from the supply side and un-primed the pump? I isolate the hot water tank with valves on both the hot and cold sides when draining the house for repairs to minimize this problem, and make sure there's no air left in any lines before restarting the pump.
     
  3. Jun 23, 2019 #3

    yelkenli

    yelkenli

    yelkenli

    New Member

    Joined:
    Apr 18, 2019
    Messages:
    4
    Likes Received:
    1
    Location:
    SC
    Update on the problem. It was trash in the Grundfoss check valve. I removed the pump, found small nodules of white material.
    Since the original plumber put in a check valve downstream of the pump, I just removed the small white plastic Grundfos checkvalve. Re-installed and it works as before.
    I called a Grundfos dealer (Snider in Charlotte). They were very helpful. Recommended to check for foreign material, and said not to worry about the overheating.
    I was also worried a slug of air came through and un-primed pump. Note: the pump sat in the system for three days (I had to go out of town). Grundfos also said to bleed the rotor/stator portion of the pump by cracking open the nut in that area. Water circulates through that area for cooling.
     
    Michael Armstrong likes this.

Share This Page