20081103

Chest Fridge


Chest Fridge
Originally uploaded by mikeysklar
I was on a useful thread with some of my homesteading buddies earlier this year. The discussion was about hacking chest freezers to be refrigerators. Just swap out the thermostat with a $16 part and you are done. My uber expensive energy star fridge/freezer sucks about 1.6kWhrs a day. That is disgusting when I could have bought a $200 chest freezer with a $16 thermostat modification and use only .1kWhrs a day (16 times less energy per day). Tomorrow you could go and vote, or you could do us all a real favor and hack a chest freezer so you stop gobbling up so much juice. Some links:

- White Paper with details (Australian guy)
- Survival Forum discussing the fridge

7 comments:

Todd said...

is it the insulation that makes this cheeper to run or the mechanics?

Mikey Sklar said...

My guess is that the chest freezers are better insulated, have smaller compressors, and due to their orientation the cold air stays in when the door is opened.

flatlanderjournal said...

We did this hack earlier this year. The idea is that cold air is more dense. Hence, you open a standup fridge and all the air cold leaves. That and the positioning / efficiency of the guts. After HVAC - biggest electricity user.

So, you open a chest freezer and all the cold air stays in. Then you plug in the unit to a brewers thermostat like this: http://tinyurl.com/5wxcwz and dial in your temp setting.

That way the freezer/fridge only turns on when you need it to go on. Ours runs about 5-10 minutes every hour.

What I've learned.
Condensation. I need to wipe out / drain about every week. Not sure if a frost free fridge would be any better. We live in Chicago area so humidity could be a factor. Definitely silicone caulk the bottom seams.

Containers. We found some plastic bins that we organize everything in. Sometimes a pain in the butt when you need something on the bottom.

Guests who don't understand the concept keep setting things on top of it like it's a counter top. Like drinks, food, etc. Can create a mess and they think you're a bit strange.

Otherwise. It does use less electricity. Although I haven't measured it. A fun experiment and I can turn it into a freezer at anytime.

btw. I've found that high efficiency fridges are really, really expensive and shipping is outrageous.

Hannes said...

My fridge sucks about 0 kWhrs because I don't have one :) Me and my girlfriend don't buy stuff that needs cold.

Asher said...

Just got mine working using the original mechanical thermostat cold control switch that came with the freezer!

Some newer units may have digital thermostats and the info below won't apply.

Most mechanical cold control switches have a small calibration set screw beneath the temperature control dial knob(usu. requires removing the dial knob to access the set screw). Adjusting the set screw changes the nominal set point temperature of the thermostat.

Here's the procedure I used to recalibrate the freezer to operate as a fridge:
1) Plug in. Compressor should turn on and begin cooling the chest.
2) Set the temp dial at the middle setting.
3) Place remote probe of dual-temp indoor/outdoor thermometer inside the fridge.
4) Remove the dial knob (pull directly out from the control switch).
5) When chest reaches your max desired operational temp (e.g. 43 deg F), turn the set screw clockwise until the compressor shuts off. Count turns carefully so you can return to original calibration if this fix doesn't work (best to mark a line on your screw driver to keep count of the turns). My switch required about 6 1/2 turns.
6)Open the chest door so that it will warm up relatively quickly.
7)Monitor the max temperature reached when the compressor comes back on.
8)Close the door and monitor the the low temp at which the compressor shuts off.
9)Repeat 6-8 a few times to verify repeatability. If the temperature differential between the min and max is around 5 deg F as it was in my case, means that your freezer is now working at refrigerator temps at your new set point, e.g. 40degF +/- 2.5degF. If the differential is too large, i.e. greater than 10degF, this fix won't work and you'll have to return the set screw to the original calibration setting and try something different like a brewers thermostat that over-rides the existing thermostat.
9)Reattach the dial knob and fine-tune set point with the control knob as desired.

Amri said...

How's your chest fidge now? Is it still working?
I read somewhere that his chest fridge failed after 2.5 years, due to corotion caused by condensation on the aluminium coil.
I think it's time to find another prove of eficiency for a long term use, before I try to convert mine.

Mikey Sklar said...

@Amri:

I've been using mine for 1.5 years with no issue. Excellent energy savings.