Just Browsing Fridge fan

DWWood

Active Member
Jun 26, 2016
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Yarra Valley
Hi guys, after last summer's 4 or 5 consecutive 40 degree days and the fridge struggling to maintain a cooler temperature I've been googling ways to efficiently remove heat from behind the fridge to better manage the temperature inside the fridge.

Most seem to use computer fans however I came across a pre-made assembly as per the attached photo and eBay link that sits in behind the top vent.

Does anyone use and if so where did you buy from? The seller hasn't got back to me after sending a couple of emails. Cheers.

https://www.ebay.com.au/itm/CARAVAN...e=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

fan.JPG
 
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mikerezny

Well-Known Member
Sep 11, 2016
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Mount Waverley, VIC
Hi @DWWood,
there are many ways to improve the performance of 3-way fridges. Adding a fan is only one of them.

If you search through the forum you will find that this topic has already been raised and discussed many many times.

But briefly, the other main improvements are:
1: ensure the top and sides of the fridge are completely sealed from the back compartment.
2: consider adding a shade cloth to the off-side of the van to ensure the sun does not fall on the vents and thus ensure cooler air entering the compartment.
3: ensure there is no gap between the body of the van and the cooling fins. i.e, most of the cool air coming from the bottom vent flows through the cooling fins. Later Jaycos have now added a piece of sheeting to do this.
4: consider adding an internal fan to efficiently circulate the air inside the fridge. This also reduces or eliminates frost buildup on the cooling fins which reduces cooling efficiency.

With these basic improvements and a few others, I don't have any problems running the fridge at 4-6C and the freezer at -15C in summer on days of around 40C

Now, $130 seems like a lot of money. A much cheaper alternative is to buy a good, quiet, and efficient fan online for about $20 and head off to Jaycar and buy a Normally Open thermostat and some cable and a fuse for a little over $10. You can pick the thermostats up on eBay for around $1 and they come in 5C increments. I use 50C.

I would have a few issues with fitting this device:
1: What is the current draw? The fan I have is a 120mm BeQuiet PureWings 2, draws only 90mA and shifts 51.4cfm. It was a little over $20 from PCCaseGear in Melbourne. It is way better that the standard fans available at Jaycar etc.
2: How much noise do these fans make when running? There seem to be three small fans and look to be less than the normal 120mm fans, they will also be spinning faster than a 120mm fan. More noise, less reliability, less efficiency, higher current draw.
3: the 40C thermostat is too low. In 40C heat the fans will be turning on and staying on regardless of whether the fridge is running. Come home, a few hot days with the van parked and come time to take it out and the fans have flattened your battery.
4: This plate has almost completely blocked the top vent. If the fans fail, it will get very hot in the rear compartment and the only solution will be to remove the entire assembly.
5: The switch is only accessible by removing the external vent. If you look at the flimsy catch that holds the vent in, it is not designed to be removed regularly. Break the spiggot and you have to replace not the vent, but the external frame.
6: My main concern. The back compartment serves TWO conflicting purposes.
One is to create airflow to coll the condensation fins at the top of the fridge. So, good airflow from the bottom vent passes over the cooling fins and exits through the top vent. This creates a chimney effect when the top vent is above the cooling fins. NOTE, that on camper trailers this is not possible and the top vent is about level with the fins and thus cooling is not as efficient. In older camper trailers, the top vent was inside the van cut into the benchtop and they worked better BUT that is now illegal due to improved gas regulations.
The other is the boiler, which for efficiency should be kept hot and NOT cooled.
I experimented with one and then two fans. The performance with two was less than with one because the second fan, fitted over to the right ended up drawing HOT air from around the boiler (and cooling it) and then drawing it past the cooling fins.
If you look at the assembly. They are mounted mostly towards the right. The hottest part of the condensation fins is actually on the left.

I hope this helps you make an informed decision.

Apologies for the long posting. This is one of my pet subjects. I wanted to avoid having to change to a compressor fridge PLUS the extra battery and 200W of solar panels to keep the power up to it.

cheers
Mike
 
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Crusty181

Well-Known Member
Feb 7, 2010
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Mentone, VIC
I think @mfexpanda has one of the clip in replacement vents below if you'd prefer not to attached your own fan to the vent. As @mikerezny mentioned re the air flow, I think these still retain the free flow around the fans.

Ranger 12V Caravan RV Fridge Vent Twin Fan - Dometic Thetford 3 Way Fridges
s-l500.jpg

I have the same @mikerezny BeQuiet Pure Wings 2 fans cabled tied to the rear of my upper vent; $25ish and they are incredibly quite, low power and good air volume. I cant see the value in your ebay offering and to add to @mikerezny 's comments Im always very skeptical of anything like that which is advertised without any reference to its capacities or power etc ... especially when they're asking that kind of coin. If your expected to pay extraordinary amounts I would expect the specs to be in BOLD and jumping of the page
 
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Drover

Well-Known Member
Nov 7, 2013
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QLD
Other than what @mikerezny mentioned in regards to making sure the back of the fridge is sealed up properly, I wouldn't go for a fan set like that which really closes off the vent area, if you have a fan failure, loss of power for some reason you will loose the flow, I have fitted many fan set ups and have found a couple of computer fans zip tied or sikaflexed to the vent work very well and still allow air flow if power fails, with a switch incorporated with a temp switch , usually 70 deg spring clipped to the upper fins to run them.
If done properly once fitted you hardly ever need to revisit, I prefer to fit the fans at the top for ease of access when on road if needed.