Running Cruisair in cold water

Discussion in 'Winterizing' started by Irie308, Oct 25, 2017.

  1. Irie308

    Irie308 Active Member SILVER Sponsor

    May 28, 2013
    2004 Sedan Bridge, GHS Hydraulic Lift
    Highfield 290 RIB with 8 hp Tohatsu
    Cummins 450C 8.3 L Turbocharged
    Does anyone know the threshold for the external water temps before the heat/ac stops producing heat. I'm staying in the water again this year over the winter and would like to run the heat as long as possible before winterizing the AC system. I have a few interior projects i would like to complete before the dead of winter but i believe there is a cutoff where the heat pump can no longer produce heat based on the water temps.
  2. ENstig8or

    ENstig8or Member GOLD Sponsor

    Jun 4, 2013
    New Jersey
    2003 Sea Ray 450 Express Bridge.....

    2016 Sea Ray 21 SPX BR
    Cummins 480CE (450)
    Mercruiser 4.3L (21 SPX)
    Mine will function reliably with the water as low as 37 degrees. Any lower and it throws an error and shuts off.
  3. Creekwood

    Creekwood Well-Known Member GOLD Sponsor

    Apr 26, 2009
    Oakville and Georgian Bay, Ontario
    '97 330 Sundancer, Raymarine C80 suite with radar, Mercury 310 Hypalon w/8hp Yammie 2stk
    2X 454 carbs w/ vDrives
    The problem is that the coils will freeze up in cold temperatures, which can freeze the seawater in the coils. I guess in salt water it might be OK, but one fall I was winterizing water systems and it was really cold that day so I ran the heat while winterizing the rest of the water systems so I could warm up periodically in the cabin. The water in the AC coils froze while I was doing it and I had to wait for them to thaw out before I could run antifreeze through. Again, may not be an issue if you are in salt water.
  4. Irie308

    Irie308 Active Member SILVER Sponsor

    May 28, 2013
    2004 Sedan Bridge, GHS Hydraulic Lift
    Highfield 290 RIB with 8 hp Tohatsu
    Cummins 450C 8.3 L Turbocharged
    Currently in brackish water. I hope to be done with the bulk of the work by mid December. My guess is that the water should be in the 40s or low 50s by then.
  5. BlueYonder

    BlueYonder Member

    Jan 12, 2015
    Chesapeake Bay
    QSC 8.3 600
    Should work with water temps down to 40F. Any lower and you risk damaging the condenser.
  6. carterchapman

    carterchapman Well-Known Member TECHNICAL Contributor SILVER Sponsor

    Mar 25, 2008
    Lake Chickamauga/Marietta, GA/Ft. Myers, FL
    2006 Sea Ray 58 DB
    MAN CRM V8-900s, Twin Disc Drives; Onan 21.5 Generator
    I'm with Creekwood and BlueYonder - below 40° water temp and you risk freezing the coils as the reverse cycle extracts heat from the water. We had two boats on our dock in Chattanooga burst coils during a particularly cold winter a couple of years ago...
  7. RollerCoastr

    RollerCoastr Well-Known Member

    Nov 15, 2007
    Cedar Point, OH / Miami, FL / MacRay Harbor, MI
    1997 400DA
    340HP 7.4 Mercruiser Bluewaters
    Garmin 741, 742, 8212, 24HD, Intellian I2
    1999 280BR
    Twin 250HP Merc 350 Alpha Ones
    40° is Dometic's documented minimum temp. As a year-round "boater" in Michigan, I could get reliable heat from water down to about 37, and carefully, very carefully get them to run in as low as 33-34°. (not that I'm recommending it)

    In order to run reverse-cycle in 34° water, the unit has to pull-in warm air. I'd point a space heater at the air intakes and run the fan for an hour or so to warm-up the unit. Once it's running, it could produce heat without freezing up, but again, this isn't advised. I would watch the through-hull discharge very closely and shutdown the heat the second I noticed reduced flow.

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