Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Glycol blues what a mess

Bigheadtodd_2 Member Posts: 12
Not sure what it is or what caused it but could use some help to solve the problem. Long story short. Working on a job that is less than 3 years old. System has Geo and back up boilers that do indirect hot water, radiant floor, supplemental fan coils, snow-melt. 6000 SF house.  The problem is system keeps having pump failures. We have had multiple failures. Clues, when I open up pumps, have found small blue green crystals, little larger than sugar, located in bottom of pump body were the impeller is. All pumps are Grundfos, different sizes have failed. I think what is killing the pumps is that the crystals ( can anybody tell me what crystal are?) in getting in-between the impeller and shaft and blocking the fluid from cooling bearings. I think the stuff had to come from the glycol. Tried to filter out of system got only maybe 5 once so far.

My question, what is it? what caused it? how to I get it out? Have burned up 7 pumps so far in last 2 years ( expensive pumps) located in different areas of system.  There are two 120 gallon buffer tanks in system, I suspect both tanks have lots of the stuff at bottom. Thanks for the help big head Todd


  • bill_105
    bill_105 Member Posts: 429
    Perhaps a longshot

    Does the boiler have an Alum. heat exchanger? And, what about the Glycol? I know some guys that had similar things in Nome.
  • Plumdog_2
    Plumdog_2 Member Posts: 873
    Which way are your pumps mounted?

    Impeller at the bottom would indicate the motor is vertical, and if the pressure goes low, they will burn out. I think they should be horizontal unless there's no other way. What kind and how concentrated is the glycol. Too much will burn them out also.
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,285
    edited July 2012
    Do your buffer tanks...

    ... have anodes in them?  (glass lined steel tank)   If so and if they are aluminum anodes, that could be the source of the trouble, if plumbing permits water from the bottom of the tanks out into the system. 

    Yours,  Larry
  • Mad Dog_2
    Mad Dog_2 Member Posts: 6,882
    Obviuosly no heat exchanger

    I know "THEY" dont wanna hear it, but a HX will save your hiny and save the HO ALOT of service calls.  Mad Dog
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    I think bill and Larry are on to something...

    Change or eliminate the anodes. They really don't need to be there is someone is maintaining the fluid pH and freeze protection. As someone else here said, the crap that comes off of aluminum is the same stuff they use for making sand paper rough. Aluminum Oxides. That will eat your bearings...

    Good to see you my friend. Don't be a stranger ;-)

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • hot_rod
    hot_rod Member Posts: 22,105
    taking on a lot of makeup water?

    sounds like a lot of fresh water is being adding to the system, maybe?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Karl Reynolds
    Karl Reynolds Member Posts: 62
    Glycol Blues

    I'm assuming that these are "TP" series pumps.  Get the serial numbers off the pumps and call your Grundfos Rep.  Chances are the pumps were not ordered with the "RUUE" glycol seals.  "RUUE" seal kits can be ordered but make sure you specify the 16mm or 22mm shaft kit.  Not an easy repair while the pump is installed.  Grundfos recently added catalog numbers for pumps with "RUUE" seals factory installed.  Make sure any future replacement pumps ordered have these.
This discussion has been closed.