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  1. #1
    Join Date
    Jul 2009
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    In a mechanical room....
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    1,888

    Freeze question ?

    I'm in south Florida and I severely doubt it could happen but how cold would it have to be for how long to freeze a plate heat exchanger, it's a 200 ton chiller so the heat exchanger may hold 20/30 gallons of water. No glycol or brine obviously in Florida. No heaters no water flow.

  2. #2
    Join Date
    Dec 2008
    Location
    Dixiana, AL
    Posts
    2,611
    That's a loaded question, Chris. What has to happen is for the water to freeze solid. According to what I've studied in physics, water starts to expand around 34 degrees, and the expansion rate increases once the fluid is totally frozen, thus causing the rupture. Since water freezes at 32 degrees, theoretically a freeze rupture can take place at that temp if it stays there long enough. Obviously as the temp drops, it takes shorter time frames to freeze, and alot of the answer in this case would be dependent on surface area of the HX, what is it mounted on, what is it insulated with, etc. Takes a LONG time at 32* to do damage, but who's to say at 10* (which is what it's been on my front porch the last three mornings). If you're concerned, you may want to stick a heat lamp on it temporarily - that's what we do. Better safe than sorry.

  3. #3
    Join Date
    Jan 2008
    Location
    windy city
    Posts
    4,439
    10 in 'bama!!!!!!!!! what is this global warming?

  4. #4
    Join Date
    Dec 2008
    Location
    Dixiana, AL
    Posts
    2,611
    Quote Originally Posted by heavymetaldad View Post
    10 in 'bama!!!!!!!!! what is this global warming?
    Where I live is 1 of the 2 coldest places in our fair state (the other being Valley Head). Consistently 6 to 10 degrees colder than other places in the same latitude, depending on wind direction and speed. We've often wondered about this so-called global warming thing............

  5. #5
    Join Date
    Mar 2003
    Posts
    7,326
    run the pumps

  6. #6
    Join Date
    Jul 2009
    Location
    In a mechanical room....
    Posts
    1,888
    Can't run the pumps boiler's on same loop. Thanks for the suggestions guys.

  7. #7
    Join Date
    Oct 2006
    Location
    Central Texas
    Posts
    638
    Sounds like it's a two pipe system, just drain it, it'll be isolated.
    Sic Semper Tyrannis.

  8. #8
    Join Date
    May 2006
    Location
    N.E. IA
    Posts
    512
    Quote Originally Posted by chrishvacman View Post
    Can't run the pumps boiler's on same loop. Thanks for the suggestions guys.
    Crack the valves and run warm (HOT?) water through it????????

    NAH. Too risky.!!!!!!!!!!
    "Wheel" mechanics work on "Wheel" chillers

  9. #9
    Join Date
    Aug 2002
    Location
    Southold.calm
    Posts
    5,853
    Why, can’t you run the pumps with limited flow?

    Your below design conditions do what you have to protect the equipment.

  10. #10
    Join Date
    May 2006
    Location
    N.E. IA
    Posts
    512
    Quote Originally Posted by pecmsg View Post
    Why, can’t you run the pumps with limited flow?

    Your below design conditions do what you have to protect the equipment.
    If it is a two-pipe system, the water from the boiler circulating through the pipes will be too hot to circulate through the chiller. Excess pressure will lift the relief valves and blow the refrigerant charge.
    "Wheel" mechanics work on "Wheel" chillers

  11. #11
    Join Date
    May 2008
    Location
    Central Pennsylvania
    Posts
    442
    Could drain it and pump er full of glycol if you won't be using it for awhile.

  12. #12
    Join Date
    Feb 2001
    Posts
    368
    If in doubt drain it.This weather should only last a few more days.Has been in mid teens in my section of bama this week. We have been patching burst coils on units all week after gas supply on boilers failed 2 nights in a row.ARRRGH.
    I want my global warming, Where the heck is it ??????

  13. #13
    Join Date
    Feb 2010
    Location
    Ontario, Canada
    Posts
    15
    Quote Originally Posted by chrishvacman View Post
    I'm in south Florida and I severely doubt it could happen but how cold would it have to be for how long to freeze a plate heat exchanger, it's a 200 ton chiller so the heat exchanger may hold 20/30 gallons of water. No glycol or brine obviously in Florida. No heaters no water flow.
    Chris that's pretty risky not having a working flow swicth on your chiller .Draining the evap may not work for you either because plate heatexchangers have a V type passage in them that do not drain .I would suggest Heat race wire set up on a outside thermostat to energize below your safe setpoint and interlocked with the chiller so it is not going to come on if your running the chiller.

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