Using high efficiency technology and making a few simple lifestyle changes can have a large impact on your daily energy use and make living off the grid much more feasible. One of the technological improvements I have made that I am most happy with is my home modified high efficiency refrigerator. This refrigerator has been my only refrigerator for 4 years and has operated flawlessly with extremely low power consumption. In this article, I will outline my reasons for the change and explain how to make the conversion so you can try it out yourself.
My motivation to experiment with a new refrigeration strategy came from my experience with my old refrigerator. It was a fairly common style of stand up refrigerator with a freezer section on the top third and it consumed an outrageous total of 5-6kwh a day! The major flaw of the common refrigerator is that the doors are located on the side. A proper design should take into account the fact that cold air is more dense that the rest of the air in your house and will drop in height when given the chance. Well, the cold air in your refrigerator gets that chance every time you open the door. As you gaze inside to select your next meal, all of the cold air rushes out by your feet and is replaced by warmer air from your living space that will now need to be cooled. Also, the magnetic door seals, no matter how air tight when they are new, will inevitably develop imperfections and allow the cooled air to seep through constantly.
An efficient refrigerator design must start with a well insulated chest style container. If you don’t want to build your own, you’re in luck because any chest freezer will work wonderfully. Cool air from within the unit will not leak because the door is located on the top. Also, each time you open the refrigerator to grab something to eat the cool air will stay inside and will not need to be recooled as soon as you shut the door.
The obvious problem with using a chest freezer as your refrigerator is that its thermostat is set for a temperature range far to low. To solve this problem, it is necessary to setup another circuit with a thermostat and relay switch to make sure the temperature stays at about 4 degrees Celsius. Basically, this circuit must turn on the freezer compressor when the temperature rises above 4 C and turn off when the temperature drops below 4 C. The simplest option would be to find a cooling line voltage thermostat with a range of 0 – 10 C but I couldn’t find one so I had to use a regular heating thermostat with a range of about 0-30 C. If I set this heating thermostat at 4 C and hooked it up to my chest freezer, it would turn on the freezer when the temperature dropped below 4 C and this would only make it colder or if the temperature was above 4 C the thermostat would never turn on the freezer! More research was needed to solve this problem.
lg smart inverter fridge found was the SPDT relay switch. An SPDT relay uses the electromagnetic force of a coil to control a switch in another circuit and this relay allowed me to use a heating thermostat to correctly control freezer compressor. When the heating thermostat reads a temperature of 3 C it will close its circuit and this will allow current through the relay coil and flip the switch to the off position. When the heating thermostat reads a temperature of 5 C, it will open its circuit and this will stop the current through the relay coil and close the other circuit thereby turning on the freezer compressor.