Refrigeration is usually the biggest drain on a boat’s power supply. Here are four almost-free ways to improve your galley refrigerator’s efficiency and use less power for your boat refrigerator.
1. Stop the Drain!
Hot air rises, cold air falls. You want to keep all that cold air IN the refrigerator box, right? But many boat refrigerators were built with a drain in the bottom so that any condensation won’t build up but will just drip into the bilge. Well, this is an open pipe for cold air to leave the refrigerator and warmer air from the bilge to enter the refrigerator.
Think of it this way: would you leave the drain plug open on a cooler? No one does. So why would you have an open drain in the refrigerator?
The easiest way to solve the problem is to stick a wine cork in the drain hole. You may have to use a knife and trim it down a bit, but you want a tight fit and enough of the cork protruding that you can remove it if you want to when defrosting the refrigerator.
No wine cork? You can use a rubber stopper or a tight little roll of duct tape to stop the air.
This one item — that takes than 5 minutes to implement — will have a huge impact on how much power your refrigerator uses.
2. Improve Air Flow to the Condensor
A refrigerator condenser needs lots of nice fresh air to work efficiently. Basically, a refrigerator works by taking heat inside the refrigerator and moving it outside the refrigerator. The heat is conducted by the refrigerant and it dissipates into the air around the condensing coils. The less fresh air around the compressor and coils, the harder the refrigerator has to work to get rid of the heat and the more energy it uses. See how a refrigerator works.
Boats are generally designed with the compressor and condenser “hidden” somewhere, often in the lazarette, the engine compartment or a locker. There is usually a cut-out for air to reach the condenser, and usually the compressor itself has a fan to keep the air moving.
To keep the refrigerator working at peak efficiency, keep the air flow pathways unobstructed and clean, and clean the fan blades, too. While you’re at it, dust off the tubes carrying the refrigerant — dust acts like a little blanket, keeping the refrigerant warm instead of allowing the heat to dissipate.
3. Do the Most Work at the Coolest Time
The cooler the air around the compressor and condenser, the more efficiently it works. So if you’re going to place a big load on the refrigerator, you want to do it when the air is the coolest.
In the tropics, paying attention to this can have a big impact on the power drain. Nighttime temperatures may be 30 degrees cooler than the daytime. By putting a fresh load of drinks in the refrigerator just before bed — instead of after breakfast — you can use 10% (or more) less power in chilling them down.
4. Keep it Defrosted
As ice builds up, it actually tends to insulate the chill plate. By keeping the refrigerator defrosted on a regular basis, you’ll make it much easier for that “coolness” to transfer to your food.
Defrosting doesn’t have to be a pain and take forever. Read my tips for quick and easy defrosting.