Fan in the Fridge

[OzeLouie]

A small fan (say 50mm) in the cabinet will reduce the problem of stratification and improve system performance.
A small fan can also be used to service the 'fridge side of a freezer / fridge divided cabinet as part of a 'Thermo-fan' system.

Suggest the following for this: (Click on pic to expand)


Using a ss heat exchanger located on the freezer side keeps the 'fridge air separated from the freezer air reducing the frost build up on the twin eutectic plates.

Regardless of how a fan is employed in a fridge / freezer cabinet, it is more important than ever to ensure that the lid / door seals are 100% as the fans agitation of air has the down side that it is also encourages warm moisture laden outside air to enter the cabinet. Suggest use VERY soft sponge seals and test with a strong light in cabinet at night, looking for light escaping indicating seal failure!

Cheers Louie

[sailcrazy]

Following. I've seen several references to fan use in a cold box in other Cruisers Forum Blogs over the past 3-4 months. One idea that seemed very doable is using a small dia computer fan in a PVC tube(to keep it free of the food), blowing lower level air into the upper fridge levels, where the cold air can settle downward and improve cooling those items on the upper levels of a cold box. Especially for those of us with a separate refer box and freezer box I'm very interested in what is recommended/tried.

[Networker]

Originally Posted by OzeLouie

A small fan (say 50mm) in the cabinet will reduce the problem of stratification and improve system performance.
A small fan can also be used to service the 'fridge side of a freezer / fridge divided cabinet as part of a 'Thermo-fan' system.

Suggest the following for this: (Click on pic to expand)
Attachment 244564

Using a ss heat exchanger located on the freezer side keeps the 'fridge air separated from the freezer air reducing the frost build up on the twin eutectic plates.

Regardless of how a fan is employed in a fridge / freezer cabinet, it is more important than ever to ensure that the lid / door seals are 100% as the fans agitation of air has the down side that it is also encourages warm moisture laden outside air to enter the cabinet. Suggest use VERY soft sponge seals and test with a strong light in cabinet at night, looking for light escaping indicating seal failure!

Cheers Louie

In a spillover, should a “spillover” fan blowing air from the freezer to the fridge be high or low, and same with the return hole, should that be high or low? Then with a “circulation” fan inside the fridge? Should that be high or low or mid, and which way should it point?

I’m thinking of putting spillover fan from freezer to fridge low, a circulation / return hole high (no fan) and a computer fan in the fridge high that blows the hot air back to the freezer? Would that work or is there a better strategy?

[OzeLouie]

Originally Posted by Networker

In a spillover, should a “spillover” fan blowing air from the freezer to the fridge be high or low, and same with the return hole, should that be high or low? Then with a “circulation” fan inside the fridge? Should that be high or low or mid, and which way should it point?

I’m thinking of putting spillover fan from freezer to fridge low, a circulation / return hole high (no fan) and a computer fan in the fridge high that blows the hot air back to the freezer? Would that work or is there a better strategy?

We suggest putting the 80mm spill over fan in the dividing wall, high up and to one side with a return air hole same elevation but as far apart as possible. The fan should draw air from the fridge and blow into the exchanger located on the freezer side. This will prevent fan freeze. (See sketch in my previous post)

Cabinet circulating fans are where you get the best result by trial and error so best to temporarily use in various spots looking for best result before fixing permanently. Suggest if possible to include blowing onto the evaporator as this will improve the systems COP and therefore cooling rate and efficiency.

Cheers Louie

[Nicholson58]

You don’t need to invent this. There are many battery operated units available. We used this on for a while but eventually figured out that the thermal sensor was badly located. Moved it. Problem gone.

Shown unit. Two D batteries. Switch eventually fails, who cares, hard wire.

[neflier]

FWIW, I've had good results with an RV battery operated fridge fan.


https://www.amazon.com/Camco-Fridge-...32310127&psc=1

[skipgundlach]

A few things to add:

I control our fridge circulating fan and puck LED lights, and on opening, the spillover fan (on which both more below), with a NO/NC magnetic switch.

The magnet mounts to the door with velcro. That's so I can defeat the switch when I've defrosted the freezer and want the entire effort of making cold to go to the freezer. Once the freezer's down to temp, I reinstall the magnet, which activates the spillover and circulation fans once the door's closed again.

I also interrupt/energize the spillover circuit with a separate electronic thermostat. Because I like my beer and Coke COLD, I have a 2 degree hysteresis (32-34F), as the amps to those fans are trivial.

I consulted with engineers when I built the spillover; the recommendation was to use a 5" (well, close) fan directly in the center of the barrier, and a like-amount of square inches at the top as an opening for the return. In my case it worked out perfectly to an inch. However, I found that I had to reduce the efficiency of the return by stuffing a tee shirt fabric gently into the gap. I just put the fan on its edge in the corner near the barrier, which moves the cold air along the bottom and gives a roughly circular flow, equalizing the temps in the reefer side, because it's running the entire time the door is closed.

I did the same for the freezer, but the thermostat there is tied to the bottom of the last plate (we have 3 evaporator plates in series, on all but the divider sides of the freezer), as is, for reasons which escape me, the standard in refrigeration; my prior read the box temps and was also on a 2F hysteresis. My current one is 6.5F, but it's about the plates. I put my circulating fan against the barrier, and the other edge at the first plate bottom; it likewise runs the entire time the door's closed, and the puck lights come on/fan-off when the door is opened. The compressor remains on/off depending on the plate temperature, so is not affected by open/closed door.

My selection of fans was first by lifetime or not warranty, and then by MTBF; all of them were so cheap I laid in replacements. I've replaced one of the small ones, in 15 years.

YMMV, of course, but it worked very well for us.

[skipmac]

Originally Posted by sailcrazy

Following. I've seen several references to fan use in a cold box in other Cruisers Forum Blogs over the past 3-4 months. One idea that seemed very doable is using a small dia computer fan in a PVC tube(to keep it free of the food), blowing lower level air into the upper fridge levels, where the cold air can settle downward and improve cooling those items on the upper levels of a cold box.

This is exactly how I did it (see post #4). Before the fan, when the fridge was full all the stuff in the bottom would freeze which spoiled all the fresh vegetables. Installed the fan in a PVC pipe and problem completely gone.

[Bill_Giles]

We only have a deep fridge. It acts like a freezer at the bottom and is chilled at the top. I guess a fan would stir the air and even out the temperature. That is not what we would want.