Fridge fan

[sinner]

Hi guys, I am looking to put a fan in to help the fridge as this year it could not cope with the heat abroad.

Question is.
Best fan
Where is the best place to put it and how do I powere it?

Many thanks

 

[Byronic]

Caravan accessory shops usually sell a simple kit. Comprises a 12v computer cooling fan and a 3 position switch ON-OFF - THERMOSTAT. The thermostat position switches the fan on automatically when the temperature reaches a certain set temperature.
The fan should be positioned high up behind the fridge expelling straight out of the vent. You may be able to get enough access by taking the vent cover off and fixing the fan on a purpose made bracket from the van exterior, if not then it's out with the fridge. Wire the positive (supply)wire to the a low Amp fused circuit at the fuse board if one is available, if not, then back to the leisure battery with an inline fuse placed close to the battery. The negative wire can be taken to where the 12v supply that supplies the fridge neg. is earthed, otherwise anywhere you can locate a handy earth.
C.A.K Tanks in darkest Warwickshire sell online fridge cooler fans.

 

[Deleted member 207]

I d double check the installation before you faff around with a fan. Surprising how many 3 way fridges are installed without complying with the manufacturers requirements. Things to look for are the tinwork that creates a "chimney effect" on the back of the fridge and positioning of the upper and lower external vents. Ideally the lower vent should be no more a few cms above floor height and the upper vent should be a few cms above the top of the fridge. Its all bout air circulation with 3way fridges. Next I'd invest in a levelling bubble to make sure that when you park the fridge is nice and level - works at its best as well.

If you go down the fan route then its best placed where it will "suck" cool air in at the lower vent, blow the air over as many of the baffles as possible and then exit via the upper vent. If the tinwork is missing then its worthwhile making up a couple of pieces to get the chimney effect working.

Most fridge fans come with a thermoelectric switch which is often set at a very low temp to turn on, 40C will have the fan running almost all of the time. I have set mine to 60C which means that it cycles on and off and seems to work quite well in temps as high as 35C, above that and its far better to have an esky full of ice.

Making caravan fridges work as claimed gives some good detailed info about baffles, venting, etc.

 

[Byronic]

Dometic/Norcold, CAK etc advise fitting fan behind TOP vent. I've found in practise that there's usually limited space behind
fridge at low level and the fan if close to the cooling coils will tend to blow a localised draft over the coils ie uneven spread.
Also sucking cooling air through the lower vent can draw in rainwater, particularly if the fan is fitted very close by.

 

[Tezza33]

I fitted two computer fans behind my top vent for the same reason, a switch and thermostat wired in to automatically cut in when required

 

[yeoblade]

I fitted two computer fans behind my top vent for the same reason, a switch and thermostat wired in to automatically cut in when required

Think I may build one into mine, what temp stat did you use for yours? I see the CAK ones use 30 - 35 deg C ones but reading the ozzy article he's using 60 deg stat

 

[Canalsman]

I am contemplating doing such a mod myself.

For a thermostat you could consider a device like this:

KSD 9700 Temperature Switch Thermostat Thermal Protectors. 40 to 150 degrees | eBay

A further refinement is to include a 12v timeswitch to only operate the fan during the day - the noise might disturb at night. I use one of these switches already and it's great:

DC 12V Digital LCD Power Programmable Timer Time Switch Relay 16A Amps ST | eBay

The switch has a battery backup too, ideal for when the habitation electrics are off.

 

[Canalsman]

Thetford supply a kit for their fridges specifically to increase efficiency in hot climates ... so I think it must help.

The system relies on heat exchange to work, so pulling a greater volume of air past the heat exchanger must improve matters. It's analogous to an engine's cooling radiator I think - running a fan to pull air though it removes more heat.

 

[sinner]

Alan, we chatted briefly at St Andrews about fridges not coping in excessive heat, like what we had in France this summer. Do you think any type of fan would work, due to ambient temps being high, all it would be doing is pushing/pulling hot air through vents, thus making no difference to fridge cooling capacity?

Quiet a few ppl sware by it mate, and as said moving air over the unit is good ;-)

 

[Tezza33]

Think I may build one into mine, what temp stat did you use for yours? I see the CAK ones use 30 - 35 deg C ones but reading the ozzy article he's using 60 deg stat

I will take a couple of photos and a link tomorrow, sorry I have only just seen this

 

[sinner]

If this is the case, I reckon fan at both ends, one pushing, the other pulling, for best results. Giz a shout, I could knock something up for a test drive. Look at PC fans first, local council tip would a good start.

Prob got a few in the attic, will look at it this week see what I can come up with, I think the hard bit for me is getting power to it ;-(

 

[Tezza33]

Prob got a few in the attic, will look at it this week see what I can come up with, I think the hard bit for me is getting power to it ;-(

You have a perfectly good 12v power supply to your fridge that works without the engine running, easy to tap off it with a separate fuse to a switch and thermostat to control the fans, you do not have to go back to the fuse box

 

[sinner]

You have a perfectly good 12v power supply to your fridge that works without the engine running, easy to tap off it with a separate fuse to a switch and thermostat to control the fans, you do not have to go back to the fuse box

don't think I can get to it without pulling fridge out ;(( full size fridge freezer built in, will check tomorrow if I can pick it up from the rear at the vents.

 

[Canalsman]

don't think I can get to it without pulling fridge out ;(( full size fridge freezer built in, will check tomorrow if I can pick it up from the rear at the vents.

Well my Thetford fridge/freezer 12v supply is on the rear of the fridge immediately behind the lower vent cover. Perfect access ...

 

[Deleted member 8180]

I've used computer fans ( some of them have a thermistor fitted already). They're fitted behind the top vent so draw air over the back of the fridge. The fins are usually hotter than ambient even in hot weather, so they're going to get cooled.

 

[yeoblade]

If this is the case, I reckon fan at both ends, one pushing, the other pulling, for best results. Giz a shout, I could knock something up for a test drive. Look at PC fans first, local council tip would a good start.

They charge at our tip (though :idea:I would of thought of it as recycling ! ) Cheaper on ebay

 

[Tezza33]

I will take a couple of photos and a link tomorrow, sorry I have only just seen this

I made a quick and simple bracket from a piece of white square drainpipe by cutting a corner a length long enough to go across the top vent then cut along it to make a 1" angle, this slotted behind the top of the vent but was pop riveted on and left lip similar to the one at the bottom, I had removed the complete top vent so that fitting was easier and no mess would go in the back of the fridge, after marking out I fitted two 120mm computer fans,
ARCTIC F12 - 120 mm Standard Low Noise Case Fan: Amazon.co.uk: Computers & Accessories


I will smarten it up later if I can be bothered but I wanted to try it first, one fan might be too close to the gas chimney so I might have to move it

I bought a thermostat from Maplins and fitted it with a switch in a cupboard under the sink, you can buy a dometic one but I wanted to control the temperature of it switching on and off, this thermostat has a sensor that you can extend up to 1Mtr so I soldered two wires on it and fitted the sensor above the fridge



I took the feed from the permantly live 12v feed on the fridge but I put a small fuse inline


the brown is neg and the blue wire is pos on mine (German built) , the red and white power the 12v element power

I tried to do it as simple and cheap as possible so might not suit everybody, cost approx £20 and I used new fans because all the ones I had were noisy, you cannot hear these even when standing next to the vent

 

[Tezza33]

Cool (excuse the pun) setup mate and, food for thought. I'd look at new alloy fridge covers, with louvers for air in/out. Fans installed to vent covers. You could also remove fans when not required.

I need to dig out my louver tool, could be a wee earner here.....lol.

You build one and I will beta test it for you, FOC

 

[sinner]

You build one and I will beta test it for you, FOC

ehhhh sorry tezza, I am his beta tester ) lol will pick it up on Saturday Terry )

 

[Admin]

I have four artic f12 fans that are behind my bottom vent. I have a thermo switch (35c) attached to the fins at the top of the fridge. If the fins reach 35c then the fans come on.