Originally Posted by mikereed100
FWIW we do not even use a fan. I just cut holes in the divider between fridge and freezer until the ice cream stayed hard when the fridge was in the low 40's. I know a fan is recommended to keep temps uniform in the fridge side, but in practical usage we have not found this to be an issue.
That's what we have found also. In the majority of installs a simple divider with holes properly placed sets up the natural convection air movement to keep the refrigerator and freezer in the proper temp ranges. But....as with most things are on boats, there are exceptions to almost every norm. Depending on the box shapes and more importantly how the box is loaded with food
and filled, some boxes just can't get a good convection air movement and on those a SMALL 10CFM air movement fan can assist. But this is where it can also goes wrong on a few fronts.
The mas es bueno guy:
on a mooring
in Morro Bay, which is a popular stopping point for cruisers way South to Mexico
, I get calls to come take a look at their system just to make sure all is well in exchange for a beer
or cocktail, which I'm always happy to do. I opened one box and immediately got a arctic blast of cold air right in the face from their freezer hatch
. They figured if a little air movement was good, then a lot is better. So they installed a Caframo 225CFM fan to pull air from the bottom of the box and blow it to the top. Holy smokes, it was like a commercial
blast freezer except that their refrigeration
unit never turned off and their refrigerator was having problems with freezing the eggs, veggies....heck they could make ice cubes in their refrigerator! Don't overdue your Box fan...more is not always better both from a power usage and air movement standpoint.
Another "where it goes wrong" is in the fan wiring
Some folks just splice the auxiliary fan into the condensing unit's cooling
fan that is powered by the electronic control module. What they don't realize is that the fan power outlet from the controller has over-amp protection and will trip off the control module if the power draw exceeds 0.5A. Now some get away with it because the auxiliary fan they choose is small enough so that even with both fans running they stay below the 0.5A draw, and then the Cruise
Rumor grows and spreads that this is the right way to add a fan.....Bad Idea. If your system doesn't have a built in spot to power an Auxiliary fan, then the best way to go is to install a low power
draw relay on your condensing fan circuit and have it pick up what ever type of auxiliary fan you want/need. This way there isn't a risk of tripping off your refrigeration
unit when you want/need it most, which of course is always when trouble happens right!