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.
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tami says
Love the site, thanks so much for tips!
Another something for the fridge is: add insulation if possible. There might be space around the reefer to add some sort of foam or gel insulation, and it’s well worth the effort
Tami says
I’m now experimenting with Spaceloft, which is a form of Aerogel insulation. It’s like a felt, sort of. Very dusty so I enclosed it in Sunbrella and built a quilt ‘box’ to line the fridge, taping/sealing it with aluminum tape. I have a pic if u want. We’ll see how it goes…
Nancy Greg Hershman on Facebook says
These are all good ideas…We on Festima Lente also hang an insulated pad off the side of the boat over the area of the refrigeration. Have an insulated pad on top of the refrigeration and have seem some cruisers that put clear plastic over the opening to keep from loosing so much cold air.
Becky says
Nancy–an aside, but I got a chuckle out of your boat’s name. The German Shepherd Kennel I managed needed names for the “O” litter, so I researched and chose “O Festina Lente” , roughly translated to ” Oh, make haste slowly ” in Latin. It fit her perfectly, and is a GREAT name for a cruiser!
Judie Ashford says
I rotate frozen containers of water from freezer to refrigerator. This helps to keep the air in the refrigerator cool during the hottest part of the day. This trick is good for keeping items not terribly vulnerable in a cooler with a rotation of frozen water bottles. I do this with produce, but would work with canned drinks or cold water, I would think.
John Ahern says
I also find that keeping a cooler for drinks is a must. That way the fridge is opened less during the day.
Bill Jackson says
Adding an extra layer of insulation, silver reflective stuff is awesome. Reflective barrier as well as a vapor barrier. R4 with single layer, R6 if you run strips, then apply full sheet.
The Boat Galley says
Definitely — Reflectix can do wonders! https://theboatgalley.com/more-refrigerator-insulation/
John Lynch says
The stopper or cork is the simplest way to stop the cool air going straight down the drain but if you can put a small S bend in the drain pipe run, condensates will form a perfect seal to prevent cool air draining out while letting the drain continue its job.
rashid says
When my fridge drain at home is clogged it builds up and leaks through the door area. How is corking a fridge drain going to actually work? won’t insulating the pipe be better idea?
Carolyn Shearlock says
The water will collect in the bottom of the refrig box and you just wipe it out with a sponge or rag. Insulating the hose won’t do the same thing, since the hose is open to the bilge and the warm air from the bilge just goes UP the hose — it’s not warming a pipe from the outside.
Sami Bolton says
Carolyn may I share this on my cooking on a boat page?
The Boat Galley says
Of course, please do!
Bruce Comeau says
Also keep it as full as posible
Frances Liz Fernandez says
Last defrost I did brush on some vodka on the freezer part where ice builds up. So far so good, it gets really cold and ice hasn’t frosted over like it normally would’ve been by now.
Edward Popka says
Also get a battery operated circulating fan to keep air moving inside the box.
Sharon says
I found that by replacing the seal around the door made a big difference in my freezer and refrigerator.
Tim Jones says
I’ve got a number of Nordic Ice packs that came with my Blue Apron kit meals. I transport the cold foods to the boat in an ice chest packed with several of these and put one in the freezer compartment and one in the refer section. Helps a lot to cool the refrigerator down quiclkly and reduce the compressor run time especially on hot days. Keep some of the lesser used items in the ice chest with more cold packs.
Mike Miles says
I always put a computer fan blowing onto the condensor at the back of the fridge. This helps enormously when the temperature is very hot. I usually fix some flexible ducting from the bilge to the intake of the small fan, and put some more at the top of the condensor and lead the hot air into the cabin. If it was very hot (unusual in Europe) I would take the outlet ducting to a ventilator thus removing the extra heat from inside the boat.
Greg Wensman says
I found that a dinghy drain plug fit perfectly!
Carolyn Shearlock says
Great news — they’ve even got a handle to make it easy to remove them!
Tina says
On my first boat I added a layer (6mm) of Spaceloft and covered with vinyl from a hardware store. Results were amazing. My second boat I did a bit better. Bought 10mm Spaceloft and used radiant barrier, 1/8″ pvc board and laminate over top. This makes cleaning easier. I also added a thermostat (by Stainless Lobster) that over rides the compressors thermostat. This thermostat also adds a defrost cycle.
Averaging about 33ah over a 24 hour period. Fridge is about 7 to 8 cubic feet and only use solar.
Have another icebox (same size) that we will be making into a dedicated freezer. Only difference will be 2 layers of Spaceloft (20mm).
Bill Yeargan says
When we travel away from our boat for an extended period, we put towels in a plastic bag and stuff it in the refrigerator. Cutting down on the volume saves a lot of energy.