Some people would like to have their boat’s refrigeration run both air and water cooled, feeling that two methods of heat exchange is better than one. Well, yes and no.
If your refrigeration system needs both to get your box down to set point, then yes, you need to use both, or get a new system.
However, if your system works fine using either one method or the other, then no, you don’t need both to run at the same time, but you still may want both methods available on board your boat.
If you want the flexibility of choosing which heat exchange method to use, then yes, having both in a single unit is good. But why would you want that choice and when would you choose one over the other?
First, it’s a fact: water is a better heat exchanger than air. The essence of refrigeration is not creating cold, but removing the heat, thereby leaving your box (and its contents) cold. Even if the water your boat is sitting in is 95°F, that water can still exchange more heat than air can at that same temperature. And quite frankly, if you’re in water that warm, the air is going to be much hotter anyway. Think: the Tropics.
But back to the why you would want both air and water-cooling in a single system – for that planned (or unplanned!) time when you are hauled out, but don’t want to empty your fridge or scrambled to eat what’s in your freezer. You can now turn off your water pump and switch on the air-cooling. Usually this means simply flipping the breaker on the pump and turning on the fan.
The clever people will already have an ON/OFF fan switch in place for this. The really clever people have Frigoboat’s air-cooled Capri 35 or Capri 50 system with a Keel-Cooler installed, which doesn’t use a pump, so an automatic savings on its 1 amp power draw.
Using Frigoboat’s solution gives you the choice to use the best refrigeration method for wherever your boat is located – land or sea.