Freezer/Refrigerator Findings

I bought a small chest freezer for the boat; less than $150 from Walmart.

The Danby 3.2 cu. ft. Chest Freezer is perfect for placement in your garage, rec room or office, and fits neatly in smaller spaces for versatile freezer storage. Use it to freeze popsicles, TV dinners, meat, fish and more. The front-mount mechanical thermostat lets you customize the freezer's internal temperature, and the foam-insulated cabinet and lid keeps your food frozen. This versatile chest freezer also features a manual defrost function, and comes with a defrost drain and vinyl-coated basket.

The intent was to put containers of water in the freezer and freeze them solid while the boat was on the trailer in the back yard. Then while on 2 or 3 day cruises I would unplug the freezer, use it as a cooler and wouldn't have to buy ice. We could also use the thawed water in the containers for drinking.

Danby chest freezer on aft deck makes a nice table.

Under normal regular use, the unplugged freezer would would be a good cooler for 6 days yielding an internal temperature of 34 - 45° as the containers of ice melted. But I like my beer really cold, about 28°.

To lower the freezer/cooler temperature, I substituted the containers of water for a 5 gallon camping jug filled with brine - 5 gallons of water to 24oz of salt. 

The jug would 'brick' in less than 2 days and as the brick melted in the unplugged freezer, the temperature inside would stay at 30° in the lower part and low 40's up on top in the basket. This was perfect. I could keep my beer cold at the bottom of the freezer and my wife could use the upper part for a refrigerator. The problem was, if I needed to re-charge the brick, the freezer thermostat only allows settings from -4.0 up to 0°, so while 're-charging', the freezer would produce 0° in the process and destroy my wife's lettuce in the refrigerator section, not to mention freezing my beer.

The solution was a remote bulb line thermostat with an adjustable setting. Set the thermostat temperature to 28°, put the bulb in the freezer and plug the freezer into the thermostat. When the freezer temp gets down to 28° the line thermostat turns the freezer off. Now we were cookin'. This setup would even make ice with the freezer unplugged.

Just for curiosity, I connected a timer to the system and used the inverter to run the freezer. After 36 hours, the inverter had been asked to run the freezer for a total of 28 minutes. I'm sure this would increase dramatically with freezer/refrigerator use, especially with me putting warm beer inside, but it did offer insight into the possibility of running the freezer with the inverter.

As it turns out, needing to re-charge the frozen brine brick won't be necessary in most cases. The system maintained easily for a week with the freezer unplugged while we were on Lake Powell and it saw plenty of use.

The line thermostat will continue to be used without the brick while the boat is on the trailer...to keep my beer at 28°.

Line thermostat mounted in plastic box. Large toggle is a bypass to use in full freezer mode. Small toggle is for an internal 12 volt circulation fan.

More pics of line thermostat.

Top view of plastic container

Inside view of line thermostat wiring

The 9volt snap is the wires for the for the internal fan switch.

12 volt muffin fan circulation tower to normalize upper and lower temps.

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I quit using the circulation tower. I like the idea of having a 'freezer' in the lower part and a refrigerator in the upper part. We buy frozen stuff for our week aboard and put it low in the freezer. That food eventually thaws but is well preserved even for the last days of a week without power to the freezer.

I've since updated the line thermostat to a simpler, cheaper construction - about an hour and $40 bucks gets the job done.

And now, you don't have to make your own thermostat. You can buy one that's plug and play.

Get one on Amazon

Oh, and I've found the 5 gallon camping jugs can be a problem, so I now use a much sturdier version - a gas can.