Monday, April 18, 2011

Fridge Fans

I know, it's been so long, I've been busy with everything, it's no excuse. I'm sitting at the Thousand Trails in Las Vegas, Nv, trying to stay cool. I've had a few requests for this when I put "had to add a fan in my fridge coils" on my Facebook wall the other day. As I watched the temperature in my freezer climb, I remembered I had bought a couple of six inch computer fans for the reason of setting up a cooling stack on the refrigerator. The ideal position is above the coils near the roof, to draw the heat up, rather than blow air up. But you have to take the top fridge cover off, stand on a ladder and all sorts of contortions. So mine blow instead of suck.

As you should know the refrigerators in out RV's use an older, more rugged technology, ammonia absorption. Rather than repeat what others have, here is a good explanation.

I thought about mounting the fans on hard mounts, either metal or wood and bracing them in the rear refrigerator compartment, but in traveling down the road the trailer flexes, so I figured the mounts needed to flex, I used nylon flex ties for mounting. (and it was a faster install)

connectors, and fans and crimpers, oh my
Getting the tools and parts ready..
Crimper, side cutters, wire, #10 push-on lugs, 14-16 push-ons, 75 degree thermal switch (NO) and 12 volt, 4.2 watt 6 inch fan.

Location, location, location
Location to place fans

one fan mounted
One fan placed to push air UP the stack.

looking up
Looking up the stack/absorption coils.

ready to go
Finished project.

wired up and running
Looking up at second fan..

heart of the system
Thermal switch and ground connector, I can pull apart the ground to open the circuit and stop the fans if I don't want them using power. I'm taking power off the 12 volt lines to the fridge board, a 20 amp fused circuit. Both fans, when on, will use about .6 (six-tenths) amps total (4.2 watts each.)

Captions for the fan, t-stat, connections

To sum it up, the thermal switch will turn on both fans about 75 F and push air up through the absorber coils, making the system more efficient. I can disconnect the negative side connecters if I don't want the fans to turn on, or the entire system can be quickly removed and later replaced for service if needed.

Addition (2-4-2012)

I moved the fans to the proper place (above the cooling fins/coils) it was very simple, I added a length of wire to the power portion of the fans and plugged it into the right places.. I also swapped out the thermal switch to a 30 degree C (86F) NO switch. I had a problem with the lower fan creating such an airflow it would suck the flame from the thermocouple making the igniter think the pilot was not on. So it was firing the igniter dozens of times, while the fans worked well during resort/electric operation, during the LP operation the igniter would fire dozens of times..

Closeup of fan in upper fridge flue..

Position of fans, and wire ties to "hang" the fans

One side buttoned up, with small wire ties, wire tie on center bar provided "strain relief" to wire going down to thermal switch/power below.

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