Power consumption is always a concern at the Hostel, both from a cost and an environmental perspective. We have introduced solar energy to provide power to our lake pump and have installed LED lighting in our soon to be completed new library. These lights consume less power than a single light bulb and yet beautifully illuminate the space.
One huge ‘waste’ of electricity has been our refrigerators. As with all vertical-door refrigerators , every time the door is opened, all the cold air rushes out the bottom and is replaced with hot air in the top Add this to the fact that temperatures in the dome are often higher than outside, the refrigerator compressors end up running continuously causing high electricity bills and reducing the life of the fridge as they burn out prematurely.
For some time we have reviewed ways of adapting chest freezers to work as fridges. The main advantage of the chest freezer’s design is that when the lid is opened, the cold air (heavier than warm air) stays inside. Chest freezers are inexpensive, around $200 for a small one, compared with $400 – $600 for a regular fridge. They are also better insulated as they are required to keep internal temps are usually at -15F to 0F, instead of 36F to 45F for a fridge. Most of the adaptation of freezer thermostats we have reviewed involved tearing the freezer to pieces and so concerns about reliability came to light.
Typical Chest Freezer
After much deliberation, we have come up with an excellent and very elegant solution. We firstly measured the consumption of the existing fridges using an inexpensive “Watt Meter” available at most hardware stores.
We found them to be consuming about 1,800-2,000 kilo watt range, costing $180 to $200 per year. With three large fridges at the Hostel, combined with high temperatures, our annual refrigerator costs were very high. In addition to that, we were wearing them out and not really getting them into the ‘nice and cold” range during the day.
Next we replaced a failing refrigerator with a new chest freezer. Chest freezers are inexpensive as have little in the way of internal trim or refinements. Then we located a very simple but highly reliable thermostat. We settled for an external device made by Jonson Controls.
Johnson Control Thermostat Model A19BAG-1E
This device has a remote sensing thermocoupler, and a grounded electrical outlet. One simply plugs it into the wall outlet, connects the freezer to it and secures the remote thermocoupler in the freezer. When the freezer reaches normal fridge operating temperatures (we chose about 33F) the outlet is simply and safely switched off. Wen it gets to be 4 degrees higher than that (37F) it simply switched the freezer back on and slowly brings the temp back down again.
The chest freezer has a lift-up lid so when its opened the cold air stays in place. Even in normal use as a freezer, it had a high-efficiency rating but when we actually measured its annual consumption over a week or so we noted it was consuming around $18 per year
We carried the tests out over about a week, taking and recording temperatures at various times of the day, paying particular attention to dinner time as the fridges are opened so much more often. Everything turned out as planned and we have replaced all of our old, worn out and inefficient refrigerators with this new approach and anticipate that we will have colder fridge temperatures, using less carbon resources by using less electricity and and saving the Hostel hundreds of dollars in electricity every year. As it is running below it’s normal load factor it should be very reliable and as no modification is made to the freezer, it’s warranty remains intact.
NOTE: The thermostat – a Johnson Control Model A19BAG-1E is available from Amazon here.