Failed closed loop pump

Discussion in 'General Discussions' started by Nathanls14, Sep 14, 2020.

  1. Nathanls14

    Nathanls14 New Member

    Hello all, back again. Looking for some thoughts from the people that are far smarter than me. This will be a winded post but I want to give as much background as possible so please bear with me.

    A little background, I had a 4 ton split geo system installed a little less than a year ago. 4 vertical wells plumbed in parallel about 30ft from the flow center/split system.

    Unfortunately I was very green with geo and didn't know what I didn't know, so I jumped in with both feet. All in all the system runs well and has saved me roughly 55% in energy/propane vs my dated conventional system.

    Anyway, I wanted to push the envelope and get as much as I could out of the system. The flow center was installed with dual 26-116 pumps (I know do, you hate them). After running the calculations for head loss, it was determined that one 26-99 pump would suffice which meant one 26-116 pump obviously would. I bought a blank off plate, removed one of the 26-116 pumps, repressurized and burped the closed loop system and thought I was golden. I calculated roughly $100/year in savings with a single pump.

    Fast forward to last week. Thursday rolls around, air is coming out of the vents but it's not cold. Go to the basement to investigate and the geo unit isn't running. Shut the system off on the ecobee, restart it, geo unit comes on and shuts back off approx. 20 second later. Feel the 410 lines, hot coming to the geo unit from the furnace and cold running to the furnace. Feel the 26-116 and hot to the touch assuming it's working. Open the unit for the fault code and it's showing high pressure. Do some research which points me to the flow center. Put the meter on the legs to the pump and it's pulling almost double amps than it should - it had frozen up.

    Closed off the loop field, pulled off frozen pump and replaced with original 26-116 I pulled off several months ago. Refilled, repressurized and burped and she's running flawless again.

    Took the burping screw off of the frozen pump, look at the inside of the screw and the pump and there is a light teal/light green slime inside the pump which is what I assume led to the failure.

    Couple of questions, when I refilled the loop both times, I used the fill off of my hot water heater. The water is from a well, that passes through a sediment filter and then through a water softener. Could this have caused the problem?

    If not, I do not remember how the loop was originally filled. Thinking back, I'm not sure if the installer used the same method, if they used a hose to the garage spigot (this is unconditioned straight well water) or if they provided their own.

    The installer is supposed to come back and validate the issue/correct as I am still under warranty. What questions should I ask, issues to bring up etc? I'm requesting that the failed 116 be replaced with a 99 and will likely do the same for the other 116 I have in the flow center.

    I do not have isolation valves prior to the flow center, should I have those added in case of flow center failure? Any need for an expansion chamber or just watch the loop psi like I've been doing?

    Just looking for some additional advice and to make sure I don't make anymore mistakes. Sorry again for the long windedness. Let me know if there are any additional details I need to provide.
  2. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Hi and welcome. The grundfoss pumps are a wet rotor design. While well water is not off the table for a early failure, debris and sand most commonly cause the failure. Does the impeller turn freely by hand? Does it feel rough or have a tight spot in rotation? You can remove the rotor assymbly from the housing and examine for scaring and wear, much like the inside of a engine cylinder. This may provide more clues.
  3. Nathanls14

    Nathanls14 New Member

    I haven't removed the rotor assembly from the housing. I did talk to the installer and there is a 10 year warranty on the pumps, they are going to order me a 99 instead of 116. When trying to turn the impeller, it physically will not move at all even when putting the majority of my weight on it with it locked in. I'm decent sized 180lbs and not a "weekling". The installer thinks it was just a bad pump, he's "seen it before".
  4. wing

    wing Member

    You should be using purified water in your closed loop to avoid any source of bacterial growth.

    Borrow 55 gallon drums or other sanitized drinking water containers and fill them at your local drinking water dealer. Cost is usually around 25 cents per gallon. Use a transfer or flush pump to replace all the existing water in your system.

    Good luck with your geo journey !

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