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Old 12-06-2014, 20:55   #1
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Circulation fan on a fridge plate

I have recently added a small computer fan to blow over my evaporater plates on both my fridge and freezer.
The change has been amazing. No more iced up plates and a more even cooling in both.
Just wired it together with the condensor element fan and hey presto.
Don't know how long a fan will last in this envoirenment but hey they are cheap so
I use air cooled refrigeration with the usual BD35s
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Old 13-06-2014, 06:36   #2
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Re: Circulation fan on a fridge plate

To clarify, you have separate evaporator plates - one for a freezer and one for a fridge?

And your fridge and freezer are separate systems?

And the new fans blow only when the compressor is running, or full-time?

Mark
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Old 13-06-2014, 07:29   #3
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Re: Circulation fan on a fridge plate

I have two, 2" computer fans inside my reefer. I am wiring them to a Velleman MK188 start-stop pulse timer to cycle on and off at fifteen minute intervals. They pull air from the cold plate and duct it up to the other end of the reefer box (6 cubic feet). I also have a pair of 6" computer fans outside the box, which run only when the compressor/motor are running. One blows cool air from the bilge onto the hot parts, the other ducts the hot air out of the compressor compartment.
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Old 13-06-2014, 17:50   #4
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Re: Circulation fan on a fridge plate

Quote:
Originally Posted by colemj View Post
To clarify, you have separate evaporator plates - one for a freezer and one for a fridge?

And your fridge and freezer are separate systems?

And the new fans blow only when the compressor is running, or full-time?

Mark
Correct only when the compressor runs.
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Old 13-06-2014, 18:43   #5
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Re: Circulation fan on a fridge plate

There are 11 different uses for fans in your boat refrigerator see Fans under parts heading on my web site.




6. Air Tumbling Fan


Conventional home chest freezers use wire baskets to allow natural air circulation throughout a box. Home refrigerators are designed to assist in air tumbling circulation by having some type of open shelving when the evaporator is located at the top of the box. The evaporator absorbs heat from the air then cool air descends absorbing more heat and rises back to the evaporator.
A circulating fan in a refrigerator or freezer will not produce good results in a box without open shelving unless a series of standoff rails are placed on the walls and floor to provide a space for air circulation.
Top opening refrigerators and freezers on boats have poor air flow and therefore the temperatures will vary from side to side and top to bottom. Without air movement in a refrigerator or freezer, temperatures tend to stratify in layers. Most commercial and home refrigerators are constructed to allow the natural movement of warm air rising and cold air descending across the evaporator to tumble the air. The addition of a small fan can help most refrigerated boxes. I recommend a one inch square muffin fan that runs at all times when the refrigeration is in use. I ran over two hundred tests to prove what works and what does not. Many are in my 12/24 volt manual.



TUMBLING AIR FAN TEST:

The thermostat was locked and outside air temperature maintained between 79 to 82˚F. for these 24 hour tests. In test 119 the food product blocks the transfer of heat. In test 120 the small airflow from a one-inch muffin fan tumbling box air, lowered temperature eight degrees at the far end of the box. This fan also increased the efficiency of the evaporator and increased Btu output from the compressor.
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Old 14-07-2014, 12:24   #6
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Re: Circulation fan on a fridge plate

I found a cool timer unit that I will be using to operate my refrigerator and freezer fans. It is a kit unit which you must assemble, but it's fun to do. It's a Velleman Mini-Kit part MK 188. It can be programmed from one second to sixty hours per cycle. I mistakenly purchased a similar kit that was a simple timer- a one-time event timer, which didn't cycle the fan on, then off, ad nauseum. It operates on 12-24 volts DC and activates a 16 amp relay, way more than enough for my little fans.
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