How about a chimney on the back of the fridge?
 

I've been thinking about trying to cool the coils on the back of my fridge, I already try to keep them clean and the fridge a few inches from the wall but does anyone know how much it would help to install a chimney of sorts on the back of the fridge? make use of the natural convection of warm air rising to pull air from the front toe kick to the back, around the compressor and up over all the coils then continue up another foot or two, it seems like a ducted air flow would get a stronger air current and keep things cooler back there.

I think it might work, depending on the design of your fridge. On my fridge, the hot air is pushed out at the toe kick by a fan, so the chimney wouldn't work.

So, it's a bottom feeder like my noisy GE fridge.. It's already using the coolest air in the room, right off the kitchen floor. :)

I wouldn't work as well if the compressor coils were embedded in the outer skin of the fridge, but there are still alot of fridges out there with coils on the back and it seems like having a way to encourage air flow back there would be a good idea, fans are good and nice but they use energy, create noise and heat rises so why not take advantage of that?

Sounds like a good idea to me. Do you have the room to do it?

To test the idea, maybe a week like it is measured by a Killawatt meter, then add the chimney and check for a week to see if it helps or harms efficiency. I'd want to know, because it might (?) take longer to dissipate heat from the coils inside a closed in chimney. OTOH, the heat in the chimney may create the exhaust flow that pulls cooler air across the coils like you hope.

Certainly worth a try, though.

Ryland, did you test a chimney behind your fridge?

I recently noticed that my fridge seems to be on for much longer now than during the winter months, this is probably because of higher temperature in the kitchen (21°-24°C/70°-75°F vs 17°-19°C/63°-66°F). I had a closer look at the coils on the back and noticed that they are not totally vertical, instead the top is about twice as far from the back wall (~4cm/1.6in) than at the bottom (~2cm/0.8in). This allows cooler air to 'wash' over the whole length instead of the top half sitting in the heat released by the lower half and compressor.

There is already a slight chimney effect since there is a cabinet on one side of the fridge. Now, what if I added a small computer fan to increase circulation? I'd run it through a transformer at a lower voltage to keep it slow and quiet, the transformer being wired so it turns on and off with the compressor. Would this airflow increase the heat exchange efficiency (resulting in shorter compressor on-time) by enough to compensate for the extra load of the fan+transformer?

I also checked that the coils' temperature was ~30°C/86°F with the compressor running, while the kitchen's temp was 21°C/70°F.
I might also close up the gap on the open side, leaving room at the bottom for fresh air.

"close up the gap on the open side".
 

We added a small thin wall section (1/2" plywood /w paneling cover) beside our Ref.
My wife said being able to see behind the ref, 'looked' bad..

You idea of adding a small fan, got me thinking. Maybe a small fan mounted at the bottom of that little side wall.?.
Just need small Hole-Saw and some screws for the fan. :)

http://i46.photobucket.com/albums/f1...0slot/b004.jpg

But, my heat dump coil is on the bottom of our unit.
Maybe I need to drill a fan hole in the floor, under the refeer?

No, I have not, not yet at least, partly because I want to lift the fridge up a few inches as well so it's drawing air from the front.
I did end up pulling the fridge out from the wall a few more inches and clearing a bunch of junk off the top because the stuff that was on the top was getting warm, the whole fridge was getting warm and the inside on a 90F day was only cooling down to 60F not the 34F it should be, pulling it out from the wall and pointing a fan at the back to move more air past the coils took care of the hot coils problem and cooled the inside of the fridge down to where our food stopped spoiling.

I think your idea is a very good one for a couple of reasons, one is the chimney effect, and the other is that if your chimney completely surrounded the condenser coils, you would also keep heat from radiating back into the refrigerator.

I have had some very interesting refrigerators. The one that had the most efficient design was actually the oldest. The design is frequently referred to as a 'monitor top', and it had the compressor on top of the refrigerator, and had the condenser coils up there also.

Here's a photo of a 1930s monitor top, not mine, but the same type.


One of the problems with conventional refrigerators that have the compressor in the bottom is that the heated air that rises off of the compressor and the condenser coils ends up transferring some of that heat back into the refrigerator, and the compressor must work to remove that heat too. The monitor top eliminated that problem.

Here's a very interesting approach that uses an existing freezer, with it's higher efficiency compressor and better insulation, but replaces the freezer thermostat with a refrigerator thermostat (beer cooler thermostat) and gets incredibly good results, of about $4 per year operating cost. Admittedly, he did start with a very efficient freezer.


Here's a PDF of this project, with all the details.

-AC_Hacker