Internal Fridge Fan

Submitted: Wednesday, Feb 20, 2008 at 17:28
ThreadID: 124472 Views:3654 Replies:4 FollowUps:0
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As a well known fridge pananoid I am on the move again.

Past readers will recall that we have two computer fans mounted at the outlet vent to assist in heat removal. In my view this has been a necessary & most successful modification. Thermostat normally set on 1 1/2.

What I have noticed is that the back wall temperature cycles between (about) -2 and +3 degrees over the cycle while at the same time the temperature in the top door compartment hovers about 5 to 7 degrees.

Last year my mate Gadget purchased us a couple of 40mm 12V fans to try inside the fridge to even the temperature front to back. He fitted his with apparent success but I procrastinated until this week, we are at Cowell & it is too windy to go out in the boat. I made up a plastic right angle bracket in which my neighbour drilled a hole the same size as the fan inlet, screwed the fan to this and then screwed the bracket between the light & back wall with the fan about 4cm from the rear directing towards the front door. I should note that we use a large plastic tub on the top shelf so there is a sort of airway where the fan is mounted, the plastic tub is held away from the wall with the light with a Papsi Max can. The fan is wired to a 12V source above the fridge and runs continuously. Gadget has wired his to the compressor cooling fan so it only runs during the cooling cycle.

The end result has so far been quite interesting. I raised the thermostat setting to 1 and the temperature, over the cycle, both rear and front the same, now varies about 1.5 to 4.5 degrees which seems pretty much ideal.

Obviously it is early days & too soon to pass judgement on power consumption but I am seeking comments from others who have played about with this type of system. Does anyone have experience with fan life?

Andy
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Reply By: Deleted User - Wednesday, Feb 20, 2008 at 18:39

Wednesday, Feb 20, 2008 at 18:39
Yes Andy this is a worthwhile mod to a fridge. I have a 90mm fan cabletied underneath the bottom shelf corner blowing up. A small fig 8 cable runs through the drain hole to a computer fan speed controller above the fridge. There is an internal M/F connector which enables removal of the shelf with fan. It runs at about half speed. I cannot see the value in having the fan only run when the compressor runs so it runs continuously when the fridge CB is on. The fridge run for seven weeks over the summer months and the temperature is more stable. Over summer when bush camping with food supplies only every couple of weeks I run the inside just above freezing. This is easy with the fan as it eliminates internal frozen cold spots. I don't have an additional external condenser fan as I found it is not necessary. Recently I picked up an hour meter for a few dollars and have connected it to the compressor fan. Nice to know how many hours a day the fridge is running.
cheers and beers
Ern
AnswerID: 574463

Reply By: Flipp'n Lorry - Wednesday, Feb 20, 2008 at 22:40

Wednesday, Feb 20, 2008 at 22:40
I like the idea of this, it is true that the back of the fridge is significantly colder than elsewhere, so circulating the air is a great idea. (I have previously installed an additional rear fan, with isolating switch and LED indicator, details posted to file swap.)

Now our fridge at home has an internal fan, which is always on, except when the door is open ('cause otherwise you blow cold air OUT of the fridge).

The trick then is to work out a way to wire the electrcis so as to use the light switch to turn the fan OFF when the door is open.

Final comment: I have noted a few boggers running their fridges around 5-7 deg to save power. Almost all dairy porducts, milk especially, come with an advice that they should be stored at 3 deg or less for longevity.
AnswerID: 574464

Reply By: Bobrovin - Thursday, Feb 21, 2008 at 03:25

Thursday, Feb 21, 2008 at 03:25
I to have the internal 40mm fan and found that the easiest place to take the power was from the power side of the light switch.

Phil and Lorraine
you could rig it to stop when the door opens by using a normally open relay from the light switch but I think that running while open would not be that much of an issue
Bob
AnswerID: 574465

Reply By: Noosa Fox - Thursday, Feb 21, 2008 at 15:49

Thursday, Feb 21, 2008 at 15:49
Andy,

We fitted an internal fan just after we met you in Alice Springs some 2 years ago now. We found the same results when running the thermostat on 1. Previously we had run it on 3 to 4 and had temperatures on top shelf of 7C and milk was going off within the use by period.

Since then the lettuce etc does not freeze if it is at the back and milk lasts well past the use by date.

I cannot understand why the fridge manufacturers do not fit one as standard when it would cost them so little to do so during manufacture.

To those people who have a van on order, if someone at BTi says it doesn't work or it is not necessary because he hasn't got one in his van, please take the advice of the forum members who have done it and found that the fridge operates a lot more efficiently than without an internal fan.

I am in the UK at the moment and today we saw a butcher with meat displayed on a table outside his shop at 2.00pm. There was no problem with it not being refrigerated as it had warmed up to 2C by that time. Would you believe that todays max temp was at 5.30pm and that was 6C.

Brian
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AnswerID: 574466

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