Maryland Pressure in loop fluctuates

Discussion in 'Maintenance and Troubleshooting' started by rebelrobin2, Jan 27, 2016.

  1. rebelrobin2

    rebelrobin2 New Member

    Hi, Newbie here. I have a Climatemaster Tranquility 27 4 ton unit. I recently recharged the loops with methanol mix (windshield washer fluid) and purged off any trapped air. Pressurized the loops to 40 PSI using a house water line. The pressure is rising and falling between 20-40 PSI over hours of operation. Is this an indication that I still have trapped air? The system is running very well, 14 GPM, Delta T is 7.5. Thanks for any advice. Robin
  2. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Pressure fluctuation can be normal dues to the fact that the pipe expands more than the fluid inside the pipe with increasing temperature. The opposite is the case with decreasing temperatures. The fact that it swings so much and come back to 40 PSI, which I assume your note meant, suggests not much air, if any, in the loop.
  3. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Keep in mind, true windshield washer fluids will have a detergent added in that may be the cause for some issues. I have no idea, but if they form soap bubbles, that would lead to air entrapment.
  4. rebelrobin2

    rebelrobin2 New Member

    Thanks guys for the response. Yes, it does return to 40, then back to 20. So you think a 20 PSI swing is OK, normal?
  5. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    I'm kinda hoping you didn't really use windshield washer fluid as loop antifreeze.
  6. rebelrobin2

    rebelrobin2 New Member

    Curt, Can you amplify on why I shouldn't use windshield washer fluid? It is water and methanol and much cheaper than buying pure methanol to mix.
  7. moey

    moey Member

    Your putting a unknown in the system the detergents are not listed on the MSDS sheets. Probably not a problem but you never know.
  8. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Yep, if you would have air in the loop, which could be compressed and expanded (think expansion tank), you would not see as much pressure fluctuations. That is why non-pressurized flow centers were invented.
  9. rebelrobin2

    rebelrobin2 New Member

    If I attached a high-level reservoir tank to the current flow center and ran with no pressure, would that work as well, less maintenance?
    Appreciate everyone's feedback.
  10. nc73

    nc73 Member Forum Leader

    I used washer fluid. No ill effects. Although I have the nonpressurized setup.
  11. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    If pressures bother you, a non pressurized system will work fine. It also makes it easier for you to clean your loops.
  12. rebelrobin2

    rebelrobin2 New Member

    Thanks Eric, I'm thinking to depressurize to avoid any future leaks caused by pressure and age. Also, I'm thinking by using windshield washer antifreeze I think my loops are sparkly clean :) I've found no evidence that if you use a winter blend fluid with no bug cleaner or defogger content it will cause system damage.
  13. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    If you are happy, that is all that matters at the end of the day. Just be sure to monitor and adjust your cleaner for adequate freeze protection as needed for safe operation of your loops.
  14. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Why buy a new flow center when an expansion tank and air separate will keep the pressure steady?

    I am not sure why people fear 12 psi?

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