Adding Circulation Fan to Refrigerator Box

[sailcrazy]

Following. Our refer has had the same issue for a long time(near or freezing on the bottom, warmer near the top. How big a fan do you use? Best to enclose it in a pvc pipe to both direct the airflow and protect the fan?

[Cpt Mark]

I used these on my separate fridge and freezer. Almost no amp draw and 7cfm is more than enough air flow.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

What I did notice was more frosting. I think I have an air opening where I can't see it. Have not been able to physically get back there yet. The frosting over went down dramatically when I turned these fans off. Besides finding the hole (where the wires and plumbing go through) I think I'm going to wire these up so they come on when the compressor cycles on.

[Alan W Johnson]

I have added a small computer fan about 3" square in the upper part of my ref. box. It runs continually. It is held off the side wall about an inch. It is located so that nothing gets stored in from of it. My thermostat measures my evaporator temperature. It is set at -5.5 C with a .5C differential (about 20F). I have a wireless thermostat in the box and the top of the box measures about 38F and if I have any water in the bottom of the box it sometime freezes but I have never frozen anything I did not want to freeze. I have toyed with putting an additional muffin fan near the base, but existing works pretty well.

[psp2psp2]

I installed a fan from an old desktop computer (12v, but very low draw) and it does the trick.

http://www.myageofsail.com

[rhirwin]

Somewhere I saw a reefer box fan unit for improving circulation that was made from a small 12V computer fan which was installed in a kitchen sink PVC J tube trap vertically mounted. The J was inverted so the fan blew the cold air up from the bottom and the J "elbow" at the top directed the cold air back down. Pretty clever

[a64pilot]

Originally Posted by sailorboy1

I am planning to just use the old 2" spillover fan and power it from the same line it was getting powered from in the past. If it had enough air flow to keep the refrig cold in the past it should have enough to just keep the air moving in the box. Plus I think the screws for it will line up with the edge of a pvc pipe that I can use a "duct"

The 2” fan will work fine, mine is mounted on the bottom of a shelf that is in my fridge and blows horizontally, under the shelf it’s pretty well protected.
My fridge is rather large at 7 cu ft and the fan is plenty large enough, I believe it doesn’t take a whole lot of air circulation , just a little bit is enough.

I’ve seen complex assemblies with PVC pipe with the fan mounted on the top and the pipe outlet at the bottom and think that’s overkill.

Rich Boren of cool blue used to sell one, but I think no longer does.

[realem]

I recently install a new fridge system cutting out the old ice box and replacing with an igloo cooler and an evaporator plate inside the cooler that I built into the galley. I did notice that the entire box did not get cold enough due to the lack of circulation. I have since installed a mini pancake computer fan (very low draw) near to top and just under the thermostat, works great. Fan is on a separate power source and on a rheostat so I can increase or decrease the circulation

[sailorboy1]

Well the hardest part of this project turned out to be cutting the plexiglass shelf because it likes to melt and rejoin itself when using a jigsaw (probably some trick I don't know about).

Cut a length of 1.5" PVC pipe so it would be high enough in the corner than it was unlikely to get blocked and mounted a little 1" cube fan on the end. Cut a section out of the bottom of the pipe to allow air flow. Cut the upper frig shelf to fit around the pipe, ran the wire (which was already there from the old spillover fan). The assembly just sits it the "slot" as I have drideck on the bottom and it is rough so the pipe doesn't slide, but it it becomes a problem I will ziptie or double sticky tape it down.

Amazing how much air that little fan puts out.

[thunderhoof]

+1 for a brushless dc PC fan. They are designed to run continuously, move a reasonable amount of air and draw little power. Make sure you have at least 1.5 inches clear on both sides of the fan and there is no dripping on it if the frig thaws. Some covering where people can reach would be good.

[rslifkin]

Originally Posted by sailorboy1

Well the hardest part of this project turned out to be cutting the plexiglass shelf because it likes to melt and rejoin itself when using a jigsaw (probably some trick I don't know about).

Use a smooth, very sharp jigsaw blade and directly just a tiny bit of water onto the blade to cool it. That avoids the melting / rejoininig problem and the smooth blade prevents chipping / cracking the edges.

[Sailing Drummer]

Just a thought - you mentioned the plexiglass shelf. If you don’t have vent holes in it maybe the cold/warm air is being blocked and not circulating.

[sailorboy1]

I have vent holes drilled into the shelf. I don't think they really do anything and that it would take a wire shelf to make any difference.

Meanwhile the circulation fan seems to be doing an excellent job. The temps at the bottom and top of the box are now fairly close to each other. The on/off cycling of the compressor has reduced and the cycle time increased. The morning battery monitor reading suggests there is 12 AH less being used at night.

[nigel1]

I'm in the process of doing the same, adding a fan to inside the fridge box.
Fan is a 4" Noctua.
Whats the general consensus, hook the fan up to the power supply so it runs continuouly, or hook it up so it only runs when the compressor is running?

[sailorboy1]

Originally Posted by nigel1

I'm in the process of doing the same, adding a fan to inside the fridge box.
Fan is a 4" Noctua.
Whats the general consensus, hook the fan up to the power supply so it runs continuouly, or hook it up so it only runs when the compressor is running?

I am running mine continuously. But I also only used a 1" fan, which is putting a LOT of air inside a 7cf box.

[chris mac]

Originally Posted by nigel1

I'm in the process of doing the same, adding a fan to inside the fridge box.
Fan is a 4" Noctua.
Whats the general consensus, hook the fan up to the power supply so it runs continuouly, or hook it up so it only runs when the compressor is running?

We run our continuous, and like sailorboy our compressor kicks in less often. So end result is same or less electrical use.
Side benefit seems to be less humidity in the fridge as well