Replacing Grundfos Pump in Flow Controller

Discussion in 'Surface Water Loops' started by QAS, Aug 29, 2011.

  1. QAS

    QAS New Member

    I believe that I have a defective pump in my flow controller. The pump itself is noisy. It does work and I do have flow, but it is making a loud whining sound on some cycles, but not on all cycles. We did have air in the system first which had its own distinct sound and had to have the contractor come out to re-flush the loop. To replace the Grundfos pump, do I need to have the loop re-flushed or can I just replace the pump itself without introducing air to the system?
  2. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Is your system a pressurised system or non-pressurised? Is your system horizontal or vertical?

    A horizantol non pressurised system should fair well with a diy pump replacement. The other not so much, it will need to be purged.
  3. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader


    Pebbles and such can cause noise.
  4. QAS

    QAS New Member

    We have surface loop in a pond, it is a pressurized flow controller. If we break into the system to install the pump, I'm afraid I won't be able to re-pressurize the system properly. Haven't found much info on how to replace just the pump instead of the whole flow center.
  5. Looby

    Looby Member Forum Leader

    A "flow center" is just a pump (or two) and a pair of 3-way
    valves designed to isolate the heat pump from the loop.
    It should be no problem to replace the pump(s) without
    getting air in the loop. After the swap, you'll have to bleed
    air from the flow center (and maybe the heat exchanger
    and hose kit), but that shouldn't require a purge cart.

    After that, you can re-pressurize the loop through one
    of the P/T ports -- with nothing more than a basketball
    inflation needle, and your domestic water supply.

    Find the flow center manual online. Read it. If that's not
    enough to answer your questions, hire a pro.

    But FIRST, make sure that the pump is actually defective.
  6. QAS

    QAS New Member

    I haven't been able to find any info on this in my installation manual for the flow controller attached. Anybody else have any more detailed info on how to replace just the pump?
  7. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    First determine pump is bad vs air in system or debris. If you do not have tools to check loop pressure and antifreeze efficacy, you are not equipped to change pump.

    A flow center has three way valves as was said.
    If you know where those are (generally on both upper sides of assembly) look inside at the round plate. There should be a 3/8 square hole for a socket wrench extension to turn the valve and some sort of "T" etched in the plate to indicate valve position.

    Look at theat "T" and compare the position of each of it's 3 arms to an opening: service port. The "T" should currently be on it's side with the base pointing at the wall (or whatever surface your flow center is mounted on). This tells you that you are open to the loop field and the hose kit but not the service ports.

    I use adapted boiler drains and garden hoses for this sort of repair. Once my valves are installed on the flow center I turn the valves so that the "T" (generally) is right side up indicating closed to the loop field but open to service ports and hose kit/heatpump.
    After making changes, you can use a run water through one service port and open the other to a drain (follow direction of flow arrows on flowcenter or heat pump). Push water through 'til air is forced out. Close discharge side to pressurize.

    Open to loop field and fill to desired pressure. Run flow center for some time (15-20 minutes) then test antifreeze protection. Turn 3 way valves to isolate service ports and remove your repair kit.

    Goofing up any part of the sequence could discharge brine into mechanical room, de-pressurize or even introduce air into loops. Every time you get into the loops you dilute antifreeze as well. So if you try and fail, make sure you get a pro to do a flush for ya and know that you at least saved money on pump mark-up and labor.

    Good Luck,
  8. K cole

    K cole New Member

    I have a -NON PRESSURIZED- QT Flow Center Model:2 2300 FC-HG that needs motors replaced. What is the correct way to replace them ????
    Where can I buy Grundfos PN:52722355 1/6 Horsepower Recirculator Pumps ???

    The Econar FAULTS in heat mode with LP and sometimes HP lockouts which says to me -low water flow-.
    Any help or suggestions would be appreciated.
  9. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Hi and welcome.
    Holy old thread batman!
    Any way the pumps are readily available online. ect. Replacing the pumps in a non pressurised unit is easy peasy. I would verify amp draw and flow prior to replacing pumps. A lp and hp lockout are two entirely different symptoms.
  10. K cole

    K cole New Member

    I've been here for a number of years reading. But thanks for the welcome. It's good to get a response.

    According to the Econar LOCKOUT evaluation LP and HP -can be- the same cause, low flow, which makes sense to me.
    SYMPTOMS are one thing but it would be difficult for me to to imagine TWO SEPARATE causes.

    HP is upload_2020-12-19_13-20-49.png
    LN is upload_2020-12-19_13-21-52.png

    Unless I have OVERCHARGED -and- UNDERCHARGED refrigerant or a sensor that detected both low and high temperature at different times.

    However I am open to any suggestions or recommendations.

    By "easy peasy" detailed EASY would be good.
    Do I (assume) need to drain/siphon the QT "tank" after shutting off the inputs ?
    The 'motors' seem to be uncommon as they are 230 volt.
    Last edited: Dec 19, 2020
  11. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    I have come to believe nothing without verification. Sensors and fault codes can go bad and give false info. Grundfos stopped production on the 26-116 and 26-99 circ pumps. The replacement is the 26-99F a 3 speed motor. It is a direct bolt on replacement.
    Shut off input and output from the flow center if possible.
    Drain fluid
    remove the 4 cap screws / they are metric size h3 from lowes
    remove motor
    clean the veloute and inspect for damage
    install new motor, do not over tighten
    replace fluid and loosen the plug on the motor till fluid escapes
    re start the unit and monitorfluid level.
  12. K cole

    K cole New Member

    I REALLY APPRECIATE your QUICK response !!! Thank you !! (It's getting cold here in MO)
    I figured the UP26-99F might work but was concerned about the mounting.
    With the high price of the TWO motors I was considering a QT Flow Center replacement for a little more money.
    Are you very familiar with the Econar GSHP's ?
  13. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    I am not that familiar with the econar box. The qt flow center yes. Unfortunately they really hose you on replacement motors. Have you checked amazon and ebay for new old stock? I would let economics and warranty guide my purchase.
  14. K cole

    K cole New Member

    I drained QT Flow Center and removed both motors. The lower one had two pieces of rusty metal in the impeller. It was also 'sticky' when I spun the impeller. It seemed to have a 'spot' in it where it was more 'resistivity' to turning. I turned both motors over so I could get to the electrical connections and reinstalled them.
    - -Question - what is the screw on the back for ? I loosened it figuring that was the plug you were referring to but nothing came out.

    Since I reinstalled the motors I have had no more 'faults' !!

    I ordered a lower motor 3-speed replacement for $340 including shipping with a 2 year warranty. There are a couple other manufacturers I found that were around $300-$325 but from what I read the Gundfos appeared a better choice for slightly more money and 2 day delivery (Wednesday) included.
  15. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    The grundfos motors are water cooled by the loop fluid. That means that any sand or debris in the loop can potentially cause a friction issue between the rotor assy and the housing. If you opened the plug and nothing came out when the tank was full, no worries. If it was not happy it would be running hot. A note on pumps. The motors do not inter change between models or manufacturers. All the pump volutes are different.
    Glad you are up and running with a spare on the way!
  16. K cole

    K cole New Member

    Pulling the pump was in fact 'easy peasy'.
    I normally charge headlong into taking things apart, figuring if someone else can do it I can too. I was somewhat hesitant to tear into the pump Flow Center with some working knowledge as it is my HEAT source.
    Thank you very much for your technical assistance. Maybe some day I can return the favor and assist you on some electronic device or other problem.
  17. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    You are very welcome! The forum here is all about helping others and leaving footprints for those who may follow. Your issue was not unique and this dialogue will help others moving forward with their problems.

Share This Page