Running Cruisair in cold water

[Irie308]

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.

 

[ENstig8or]

Mine will function reliably with the water as low as 37 degrees. Any lower and it throws an error and shuts off.

 

[Creekwood]

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.

 

[Irie308]

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.

 

[BlueYonder]

Should work with water temps down to 40F. Any lower and you risk damaging the condenser.

 

[carterchapman]

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...

 

[RollerCoastr]

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.