I did some experimenting with fans at the back of the fridge and found the most effective solution was a small fan mounted below the condenser (for the benefit of others reading this thread, that's the finned gizmo at the top) and a larger fan mounted on the bottom vent. It doesn't need a lot of airflow just enough to keep the air circulating, more than this serves no purpose. In order to test the effectiveness I used a multimeter with a thermocouple attached to the fins. I generally found the fan on the bottom vent to be more effective than an exhaust fan on the top vent. Try the fan on the bottom vent first as it may be adequate without the fan under the condenser, I haven't checked this.

A switch or thermostat needs to be installed so that it runs only when needed as apparently in cooler conditions the boiler takes longer to come up to temperature and start the cycle operating. That advice came from a fridge techie that does a lot of work on 3-way fridges.

I also installed a baffle below the condenser to make sure the natural airflow was directed over the condenser. It is also recommended that the space around the sides of the fridge be filled with insulating material, I haven't done this (yet) as it involves removal and reinstalling the fridge.

I haven't tried installing a small fan inside the fridge but it may help. I've seen it suggested that power to this fan could be routed through the condensate drain.

Try this the rear fan at the top has worked for me in forty degree heat at this time I haven't needed to install the internal fan. I have also wired in a led light beside the fridge controls to indicate when the fan is running.

http://www.dreampod.net/boroma/fridgefan.html

But I have re done the top outlet directional baffle and installed compressed foam insulation down the backside edges of the fridge. 

-- Edited by patrolst on Sunday 2nd of December 2012 10:04:43 AM

-- Edited by patrolst on Sunday 2nd of December 2012 10:15:42 AM

blaze wrote:

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Now guess who the dimwit was that removed a switch months ago as it didnt apear to have a use.

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 Mate, when it comes to dimwittery (is that a word?),  I've been there done that!

I have two mounted on the top vent pulling air out, have not been in extreme conditions as yet, just put them on a toggle switch & turn when required.

Kiwi-as mounted some when he was here a few weeks ago.

They would have to make a huge difference getting that heat out.

For many years I have had fitted two small computor fans mounted on a alloy panel inserted into a rear sliding window above my car fridge/freezer that I run when parked, the inside car temp is generaly around 5deg above outside ambient temp, cant complain about that.

JC.

 A small computer fan (draws VERY little current) worked on my parents van in Darwin heat. Need to move the air over the fins.

I just had a computor fan installed inside the top vent to extract the hot air and helps a lot. A very big thankyou to kiwi-as for doing that job for me as I am not mechanically or electrically minded at all BUT I am learning as I go.

Nomad246 wrote:

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This is a very good post, thanks Blaze for starting it.

Questions if I may

Does the fan aid better in hot weather when the fridge is on 240v, 12v or gas, or all three?

Also what about mobile on 12v or is it only run when the van is stationary?

 

Thanks

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 All three, both mobile or stationary.  However don't expect it to work wonders in overcoming the lower efficiency of the fridge when on the move.

Digressing a little, on that last point I did some tests some time ago running the fridge on (notionally) 12v for an extended period while parked level and stationary for the whole time of the test and found that it operated just as well on 12v as on 240v. I came to a conclusion that the poorer performance on 12v while travelling may be due to the constant movement rather than the running on 12v. I used a 14 volt power supply to substitute for the battery for the test, but I have been able to compare this with 14 volts supplied from a voltage booster while travelling.

Nomad246 wrote:

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PatrolST, had a look at that site ,,, wondered how the 70C T/stat came to be ,,,,, I googled and I could not find a temp of the unit. I was wondering whether a 60C or higher t/stat would be the go.

Reason behind my thinking is battery power to drive the fan (yes I know It's mA) having only 100Ah reserve.

The fridge we have is a RM4601, so it's thirsty on battery and gas, given that freecamp will be on gas, I was working toward making it more efficient on gas use.

Specs on gas use for this fridge would have a 9Kg bottle empty in 2 weeks, so if it was more efficient, maybe the gas could last longer (detriment is battery power to do this)

Cheers

 

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Hi Nomad246.

The site I put up is not any thing to do with me just one I came across, and the fan installation in our van was as a precaution at the start as we have one of the "Electrolux" 4401 103ltr fridges. We have been in 36 to 40 deg heats and the fridge works well with the fan cutting in and out as required.

As for the 72deg thermostat it was trial and error for me as the fridge is a heat absorption unit the removal of to much heat from the cooling fins could be detriment to the operation of the fridge, this is why I have found it better to pull the heat out than push it through from the bottom. Others have had success with the fans installed at the bottom.

If the fridge had had some problem with the thermostat being too high I would have tried a lower temperature one. But as is the set up is working well.

As for the gas usage we usually get 7 to 8 days from a 4.5kg gas bottle for fridge operation and cooking while bush camping, the fridge spec. Notes 18.3gm per hour usage. The fridge is mostly running on temperature setting of 4 to 5 if in cooler climates it could need be taken down to 3

Some of the larger fridges would use more per hour.

The specifications your require should be found on the label stuck to the back wall in your fridge which will note all usage i.e. gas, 240vlt. 12vlt & Gas.

Please see the insert below, which notes that, the better the fridge installation the better the performance and efficiency

Refrigerator Installation

Correct ventilation basic for top performance

 To get the best performance the refrigerator needs at least 200 cm2 free air inlet and this space should be kept until the air outlet. Behind the rear border part please leave minimum 20 mm distance to the furniture wall.   

-- Edited by patrolst on Tuesday 4th of December 2012 10:39:01 AM

3 way fridges are "thirsty" on energy, be it 12v, 240v, or gas. If it were not for the convenience of being able to operate on gas 3ways would have been assigned to the dustbin of history long ago. Operating a 3way on 12v only makes sense when connected to the vehicle's main battery and the engine is running, such as when on the move.

The battery power required to drive a suitable exhaust/inlet fan such as a Jaycar YX-2574 is only 80 milliamps or 0.08 amps so the draw on a 100ah battery is tiny.

It's my (very limited) understanding that the temperature of the condenser would ideally be about 40-45 degrees C. On this basis I think a 50 degree thermostat such as a Jaycar ST3831 attached to the fins would be appropriate. Note that the type of unit required is a normally open one (not normally closed). That is it closes ("switches on" in non-techiespeak) when the temperature exceeds 50 C.

It would be interesting to follow this up with a qualified absorption fridge technician as I'm a little out of my league here.

G'day PatrolST,

I think you have uncovered the most impotant info here ,,, "with sufficient airflow to the ambient"

this appears to me to mean that best operation is the ambient temp of airflow over the condensor fins. Hence forced airflow at whatever the outside air temp is.

I assume that if the area around the fins is allowed to rise (due to improper ventilation) above ambient, the internal of the fridge does the same, rises above desired.

Crude , but logical to me, so all the fridges that are installed with "good air circulation" as per requirements do not present as a problem. However installs that may be borderline potentially have cause to overheating (above ambient) and lesser cabinet efficiency.

Taken from this it can be determined that the ambient air temp in Aus is generally not above 45C. So a 50C t/stat would ensure proper operation,,, even a 40C t/stat would, but the fan may be running un-neccessarily on hot days.

Also,, we run 9kg bottles so your days between fills agree with our assumed usage.

Seems as a conclusion that if the fridge is installed "absolutely perfectly" by the van manufacturerer then it will work as intended. However if there is the slightest flaw in installation then forced ventilation will assist in efficiency.

I'm of the view that spending around $50 on parts to install yourself will be a good safegaurd for what could be hundreds of dollars of food in the fridge, not to mention where you are to go and shop to replace spoilage.

Dilemma now could be ,,,, why spend $000's on a van without failsafe ventilation for the fridge worth $0's.

Guys, thanks for your input.

PS: I've found this beneficial because my business background demands 100% redundancy (backup) with costs to be considered.

cheers

patrolst wrote:

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As the post did not display the correct details I included please find them here./

http://www.dometicrvcentre.com.au/documentmanager/item/421

-- Edited by patrolst on Tuesday 4th of December 2012 10:50:03 AM

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 This site shows insulation wool between the fridge & cabinates, both top & sides.

How many have got this?

We have the heat deflector plate as original equipment.

JC.

Nomad246 wrote:

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Failing to see the relevance of your post JC ,,,, where are you heading with that comment

You  "have the heat deflector plate as original equipment" ,, enlighting us what that does and why the comment on insulation that probably isn't there

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Nomad 246

I think J.C. is referring to the "Dometic" fridge installation procedures that I posted where it shows that the fridge should be installed with insulation down the sidewalls and top of the cabinet.

I doubt very much if the caravan manufactures would bother to carry out this installation procedure, a lot of the time and the fridge installs I have seen they have difficulty installing the directional heat baffle at the top outlet properly.

justcruisin01 wrote:

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patrolst wrote:

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Nomad246 wrote:

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Failing to see the relevance of your post JC ,,,, where are you heading with that comment

You  "have the heat deflector plate as original equipment" ,, enlighting us what that does and why the comment on insulation that probably isn't there

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Nomad 246

I think J.C. is referring to the "Dometic" fridge installation procedures that I posted where it shows that the fridge should be installed with insulation down the sidewalls and top of the cabinet.

I doubt very much if the caravan manufactures would bother to carry out this installation procedure, a lot of the time and the fridge installs I have seen they have difficulty installing the directional heat baffle at the top outlet properly.

 

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 EXACTLY Patrolst in a nut shell.

Nomad 246, the web sit shows the wool insulation very clearly & as Patrolst said no one installs it .

Insulation makes a big difference to a lot of things, A fridge in a cabinate with a cavity all around it with no air flow then the unit will struggle from heat build up.

I beleive my point was valid & obvious.

JC.

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 Valid and obvious ,,,,, the only thing that is obvious is that many users have issues with installed fridges. It is of no relevance to quote a premium way to install when what we have is what we got.

It is easy to "quote the manual" but many did not build the van and yet seek better results.

We all agree that if things were done to the manual, then nobody would have issues,,, however due to van design it happens that fridges are not always installed to the best result. A pompus attitude that you have would see the the van gutted to install as the manual required.

However this pursuit is about rectifying a negative to gain a positive outcome without building a van around a fridge, nor having an attitude that says what we bought was stupid. I also have a OEM heat deflector plate but I believe that there is gains to benefit from ,,,, even if everyone should have a fridge installed by the manual. Which not many has.