Loop Antifreeze and GT Flow Center

Discussion in 'General Discussions' started by Kdeclercq, Jan 9, 2009.

  1. Kdeclercq

    Kdeclercq New Member

    I live in a cold area of upstate NY and recently (October 08) installed a WF Envision 064 with a closed loop. I am having problems with low water flow which I believe is because of freezing up of the lines. I base this on I am supposed to have 7 600' lines, but one had a leak and was shut down early on. Another developed a leak during operation and went undetected for some time - 3 to 4 weeks maybe. That line was corrected and is fine now. My system automatically adds water and is the main reason I didn't detect the leak. So operationally I have 3600' of loops vice 4200', and I don't know how much the antifreeze was diluted. The unit will lock out because of the low flow when operated during heavy heating loads. It works fine when conditions are milder. The antifreeze came precharged in the lines, and my contractor installed the lines in the loops and I added water from my well. I know I have lost antifreeze, I just dont know how much. The antifreeze is or was an ethanol concentrate to protect down to 10F.

    So, I can use any advise out there especially on or about antifreeze. Where can I get it, How do I add it, and where do I add it, I can add fluid at either supply or the return sides if I knew how. What is the best way to test the concentration. I have read info about a GT Flow Center that is non-pressurized, and useful to add antifreeze, but they are a lot of money and I already have a flow center. Any thoughts?
  2. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    How much is enough

    It is fairly easy to find out how much you are protected in regard to anti-freeze. You have said that you have a autofill, that is good and bad.
    You need to get a alchohol specific hydrometer, readily available at beer and wine making supply houses on the web. Draw off a sample of your loop fluid and test. There are charts available that relate the percentages to degrees of protection.
    Adding alcohol to increase the percentage can get a little harry for the un initiated. Have you contacted the installer about testing the mix?

    A quick way to tell if freezing is causing your lockouts for sure is to measure the incoming and outgoing water temp of your loop. when you have those numbers it will tell you alot.
  3. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader


    To sum up - get a hydrometer in the range of these common antifreeze mixtures (the wine store ones are often good enough). Using this you will get a specific gravity number that you can then use an ethanol chart to look up what % is in your system.

    You can often buy bulk ethanol at a fuel supplier or autoparts supplier.

    You don't need a new flow centre. If you have P/T plugs you can likely introduce antifreeze in the system through these ports. It takes some monkey wrenching to put together your own pump that will work in a port like this, but it can be done. A bucket pump can work for example.

    Also, your low flow lockout can be due to air lock problems or air working its way towards your circulating pump. This would be a common result a loop leak would cause. Having your system re-purged and pressurized would ensure this isn't the issue. Antifreeze could then be added at this time as well.

    Side note: having makeup water in a system such as this can mask issues as you've noted. There is no reason a system would require makeup water other than that it is leaking, so I would encourage you to close the valve.
  4. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Move quickly to resolve this - loss of freeze protection can result in rupturing heat exchanger in unit - very expensive to repair
  5. Kdeclercq

    Kdeclercq New Member

    Thanks for the inputs.

    A follow on question. If I can figure out to how to reload the antifreeze, should I stick with Ethanol or switch to Methanol (I gather a lot of systems use that)? Thanks again!
  6. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader


    For the hassle of switching, I'd stick with ethanol. But methanol is our choice around here.
  7. Kdeclercq

    Kdeclercq New Member

    Purged & Working Thanks

    I cobbed up my own flush cart using a 32 gallon plastic trash can & 1HP sprinkler pump that I had, along with some PEX piping, sharkbite connectors, etc and replaced my loop fluids with a 21% methanol mix. The system seems to be working fine (almost 24 hours now with no shut down & pressure remains constant). Before under the same conditions it would lock out if it ran for very long and especially in second stage and the pressure would rise significantly as I assume the fluid was slushing up previously.

    Thanks again for everyones input. Now I have to figure out if I need more pressure in the system as it is rock steady at about 18 PSI and only wavers when the system shuts down or starts up. Is 18 PSI too low or should I leave better off alone?
  8. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    Sounds like you made a lot of progress. Way to go:D:D

    18 psi is OK just barely. It might drop as the cooling season ends, if so bump it up a little.

    We usually run our systems between 20 and 30 psi.
  9. Kdeclercq

    Kdeclercq New Member

    Sucess I Hope!

    I tried posting this yesterday, but something happened.

    I cobbed up a flush cart using a 32 Gal Plastic Trash Can, a 1 HP Sprinkler Pump, Some sharkbite connectors, Pex Tubing, and purged the loops and replaced the antifreeze (If I had any left) with Methanol. The system has run fine since - no lockouts (The Alberta Clipper hit yesterday), no emergency heat coming on. The pressure is low (18 psi) but is rock steady except when the system turns on or off of course. Is there a magic number for pressure or leave well enough alone?

    Thanks again for all the advise.
  10. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    see my post above yours

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