Internal Fridge Fan - 100% result

Submitted: Sunday, Mar 30, 2008 at 19:18
ThreadID: 124597 Views:48252 Replies:4 FollowUps:5
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Previous postings have recounted, ad infinitum, our fridge fan (internal & external) modifications, another change last week has, I believe, finally achieved the ultimate configuration.

Some time ago I recorded fitting a small internal fan for circulation. This was a 40mmx40mmx10mm unit mounted (screwed into the fridge wall on the thermostat side with the mounting between the shelf spacings) on a right angle section of plastic with a 30mm hole cut over which the fan which was mounted pushing air away from the back wall. The fan is set about 1 1/2cm from the back wall.

This installation dropped the temp in the top door compartment from about 8deg to about 3deg.The next issue was fan noise, sounded like a DC3 taking off. Mulled over this for some time & decided a better fan with speed control was required. Not so easy. Eventually purchased a bit of a fan collection & a Zalman Fanmate2 speed controller. Decided to try a 50mmx50mm fan on the basis that it would shift more air at low speed.

After installation noise problem solved but measurements around fridge revealed cooling stll not satisfactory in lower front door shelf & fruit/veg containers, about 8deg. Turned fan around. We use containers on all shelves & the top shelf container is about 30cmx40cm, give or take, so that the air is forced down. The fan is now set on minimum speed (silent) & the thermostat on the lowest (warmest) setting, the next move would be off. The internal fridge temp is about 1deg at the wall and 3 to 4deg top & bottom of the door.

Given the speed setting I think a 40mmx40mmx10mm fan would be adequate. Not an easy size to source, I purchased a couple, as part of my collection, on ebay in the US.

I tried, between fan changeover, the unit that Camec sells but found that the air could not be directed & the circulation was a bit weak.

Happy to supply more info if anyone is interested, rather than bored, by this topic.

Andy aka "The fridge Paranoid"
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Reply By: Innkeepers - Sunday, Mar 30, 2008 at 22:03

Sunday, Mar 30, 2008 at 22:03
Hi Andy,
The 40mmX40mmX10mm 12 volt fans are available from Dick Smith Electronics. Cat No Y8496.

Site Link

Hope this helps.
Cheers
Rick
AnswerID: 574834

Follow Up By: Andy1 - Sunday, Mar 30, 2008 at 22:55

Sunday, Mar 30, 2008 at 22:55
Rick

The Dick Smith fans do not have the third wire for the speed controller.

Andy
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FollowupID: 849592

Follow Up By: Innkeepers - Monday, Mar 31, 2008 at 00:47

Monday, Mar 31, 2008 at 00:47
Hi Andy,
You may still be able to use the DSE Fan if you use a voltage dropping resistor in the supply line to the fan. This will lower the supply voltage and in turn slow the fan.

If you use a potentiometer in the supply line, it will act like your speed controller and be variable. The DSE Fan is a 1.4 watt device, so a potentiometer of 3 or 5 watts will be ample. A good source of "pots" is volume controls on old Radio or TV sets....free...or DSE has a wide range of them at a cost.

Cheers
Rick
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FollowupID: 849593

Reply By: Graham & Barbara - Thursday, Apr 03, 2008 at 19:47

Thursday, Apr 03, 2008 at 19:47
Hello Andy
We have just had an internal fan installed, mounted with self adhesive velcro to the back wall and roof of the cabinet near the thermostat knob. It is 92m92m25mm and 12 volt 2 watt that moves 44 cu ft/min powered from internal light via the thermostat so only come on when fridge is operating. two wire unit but is very quite available from Farnell cost $8.73 plus freight, model no. 960-6378, phone 1300361005.
We also had a 120x120 unit fitted to exhaust top external vent, but doubt we will need to use with internal van temp at 30c and thermostat set one mark over no. one position the back of the fridge top and bottom shelf 4.7 off and 7.1 on but down to .5 overnight.
Farnell have a vast range of fans avaialbe including variable spped units view at www.farnellinone.com.au
regards Graham
Graham and Barbara

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AnswerID: 574835

Follow Up By: Wandering Wombats - Tuesday, Apr 08, 2008 at 05:59

Tuesday, Apr 08, 2008 at 05:59
Hi Andy
Would appreciate some details and photos if possible so I can see exactly what you have done and how, If you can send me a link to the site you purchased that would be great.

regards

George
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FollowupID: 849594

Reply By: Flipp'n Lorry - Tuesday, Apr 08, 2008 at 07:00

Tuesday, Apr 08, 2008 at 07:00
I do like the idea of the internal fan, but a couple of words of caution. (Just me being cautious, that's all, not knocking the basic idea).

One member (over a yarn at the last mini rally) has observed that since installing an internal fridge fan, the cycles are shorter, but there are more of them - he couldn't really say that the fridge ran less in total. That COULD be explained by the fact that the area where the sensor is located, once it finally cools to the extent required to turn the compressor off, the "cold" is then quickly dissipated by the internal fan away from the sensor area, and the fridge then commences a new cooling cycle.

It is true that the fridge is apparently cooler on a setting of just "1" (and there is no doubt that this will be more evenly distributed). But that doesn't mean the fridge is running less often - in fact, it could be running more over a full 24 hour cycle. The additional cold which is gained more evenly throughout the whole of the fridge is not "free", there are actually more compression cycles going on, with the fridge cycling more often.

The 2nd word of caution (on authority of the wife!) is that too much air circulation is just going to dry all the food out. If you only have beer in the fridge, it doesn't matter, but fruit and vegetables will suffer if there is a mini cyclone going on in there.

Finally, even if the internal fridge fan delivers the benefits of more even cooling (agreed) and more efficient cycling (maybe?), the fact remains that any heat removed from the inside of the fridge has to be dissipated through the cooling fins on the rear. I don't see how an internal fan negates the benefit of an additional external venting fan which helps to actually get rid of the heat?

AnswerID: 574836

Follow Up By: Andy1 - Tuesday, Apr 08, 2008 at 16:24

Tuesday, Apr 08, 2008 at 16:24
Phil

It all depends what you want from the fridge. As built the fruit & veg compartments & the door are at temperatures are about 7-8deg, probably higher in the fruit & veg compartments, which is at the upper limit for food storage. There would seem little doubt that the heat loss will be greater, so power consumption will probably rise although the offset is that ice is a very poor conductor so that the formation of even a thin ice layer on the back wall will significantly decrease efficiency. There is no ice formation with a bit of air circulation.

The need for external exhaust fans for heat removal is a seperate issue, we have two low noise fans mounted inside the fridge compartment at the upper outlet. These are an absolute necessity in the hot weather.

There is no drying out of contents, the fan is a 50x50mm (this is an overall dimension, not the screw hole spacing) x5mm or so unit. As the power is supplied through a speed controller the voltage is constant at about 11.5v so that the speed does not vary with battery voltage through the charging cycle. The circulating velocity is not physically noticable.

All modern domestic & industrial frigdes are fitted with circulating fans although some only operate during the cooling cycle.

We joined up with my mate Gadget the other week and changed his internal fan to a 40mx40m (screw hole) x5mm unit replacing a 40mmx40mmx10mm unit which was a bit noisey. Mrs Gadget would not be without the circulation, the fridge just becomes a better unit.

Andy
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FollowupID: 849595

Reply By: Andy1 - Tuesday, Apr 08, 2008 at 17:33

Tuesday, Apr 08, 2008 at 17:33
George

Based on the way Gadget's fan is performing I would say that a 40mmx40mmx5mm unit is adequate.The dick Smith unit is too noisey. I purchased some (Panflow 40mm x 20mm x12V 3 pin fan with RPM monitoring) from the-fan-man on US e-bay, no problems. These are not the fans I am currently using but I am confident will do the job as Gadget's fan is pretty much identical, albeit a bit thinner and without the third wire. To keep your options open I recommend you get fans with the three wire setup and purchase a Zalman Fan mate2 speed controller, I got mine from Lakes PC Parts, lakespcparts@optusnet.com.au.

As it took me half a day to post pictures last timeso I will get Gadget to take a few photos of both of our setups & post these in the next few days. Our setups are a bit different but both on the same principal and both effective.

Andy
AnswerID: 574837

Follow Up By: Andy1 - Friday, Apr 11, 2008 at 16:27

Friday, Apr 11, 2008 at 16:27
George

Run into a problem. Carefully took photos & then discovered I had not loaded the camera drivers onto the computer we are travelling with. Will get the disc sent to me.

Andy
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FollowupID: 849596

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