Jump to content

Fridge vent kit


Moor01
 Share

Recommended Posts

i really noticed how much my freezer was struggling last weekend. The fridge is on the awning side and it got hot in there while we were out.  I have spare computer fans all over since I work in IT. For ease I might just put an inline switch in, but I am unsure how easy it is to find a 12v feed from around that area?

Link to comment
Share on other sites

There has to be a 12v feed to the fridge for the controls so you may be able to tap into that.

Life is not a rehearsal . . .:)

Porsche Cayenne S Diesel & Knaus StarClass 695. Previously Audi S4 Avant & Elddis Super Sirocco

Link to comment
Share on other sites

Any nearby 12v will do the job because the fan uses so little current as to be ignored

 

On my latest Phoenix I picked up the 12v supply from the back of a lighting switch that’s located just above the worktop over the fridge. The fan draws so little current that I use speaker flex (very thin and easy to thread through small gaps) 

.

Experience is something you acquire after you have an urgent need for it.

Link to comment
Share on other sites

On our Eccles 480 the cooker ignition / oven fan circuit was easily accessible. I have also used speaker wire but I seem to remember reading somewhere that it's not a good idea.

Link to comment
Share on other sites

When tapping into an existing electrical circuit it would be good practice to insert your own in-line fuse to protect your additional fan install.

 

Link to comment
Share on other sites

On our Mk3 unicorn there was a terminal block at the back of the fridge marked with a label ‘fan’.  I tested it 12 v. Permanent Live.  Not that we needed it but worth a root around if you are intent on fitting a fan.  Not checked the Alicanto fridge works just fine so far. 

Link to comment
Share on other sites

8 hours ago, charlieboy2608 said:

When tapping into an existing electrical circuit it would be good practice to insert your own in-line fuse to protect your additional fan install.

 

 

If you can find one with a low enough rating! Computer fans draw virtually nothing, in the event of a short circuit the (very thin)  speaker wire would act as a fuse anyway, but technically yes an additional fuse should be fitted ( I have never bothered, mainly because I have taken the supply from a circuit that’s already fused anyway):

Experience is something you acquire after you have an urgent need for it.

Link to comment
Share on other sites

so just to confirm, this will help with both 240v and gas? Mine spends 95% of it's time on gas, I don't want a couple of fans blowing the flame out! Though I expect if i fit them to the top they should be far enough away from it to be fine.

Link to comment
Share on other sites

Yes will help for both power sources. Your absorption fridge uses a heating element that is heated by gas or electricity. The heat created is normally expelled by the natural air circulation of air between the lower and upper vents. The addition of fans just helps this circulation particularly in hot weather.

Life is not a rehearsal . . .:)

Porsche Cayenne S Diesel & Knaus StarClass 695. Previously Audi S4 Avant & Elddis Super Sirocco

Link to comment
Share on other sites

27 minutes ago, KnausCol said:

Yes will help for both power sources. Your absorption fridge uses a heating element that is heated by gas or electricity. The heat created is normally expelled by the natural air circulation of air between the lower and upper vents. The addition of fans just helps this circulation particularly in hot weather.

 

nice thanks. Im popping to the caravan storage on friday. I'll take some measurements and my voltmeter.

Link to comment
Share on other sites

8 hours ago, Mr Plodd said:

I have taken the supply from a circuit that’s already fused anyway):

1 Amp fuses are widely available.

The lowest I've seen in a caravan on the 12 volt side is 2 Amp.

The other reason for adding an additional fuse is it would make fault finding a lot easier if you protect your added wiring....to each there own but it is a actually good working practice too ;-)

Link to comment
Share on other sites

  • 2 weeks later...

I’ve ordered the parts ready for a test next week but probably some basic questions:

 

1. I’m planning on mounting two fans and sucking air out from the top vent,  do people install the fans behind  / inside the caravan or attach externally to the top vent?

 

2. I’ve attempted to remove the top vent, slid the clip up on the left hand side and the left hand side did come loose. The right hand side just won’t free, is there some method for removing the right hand side? I’ve tried carefully levering it, it’s as if the mastic has secured it but didn’t want to break the panel.

 

Subject to my tests next week, if successful I will probably install the fans behind and inside the caravan. I’ll attempt to drop a wire from the inside cupboard above the fridge and power the fan from one of the sockets in the cupboard (Phoenix+ 640). I may even 3D print some form of mounting bracket if needed.

Link to comment
Share on other sites

1 hour ago, D-Hill said:

I’ve ordered the parts ready for a test next week but probably some basic questions:

 

To remove the vent,  release the slide clips, hinge out by 20-30 degrees, then jiggle up and down on the left while pulling to the left. Eventually the tongues on he right will release and the whole thing can be removed.

 

In my case the fans are mounted on a thin gauge ali plate that is sandwiched in place by refiitting the cover. The fan plate can be removed by simply removing the top cover, unplugging the cable, and lifting it out.

Just now, TinShack said:

 

To remove the vent,  release the slide clips, hinge out by 20-30 degrees, then jiggle up and down on the left while pulling to the left. Eventually the tongues on he right will release and the whole thing can be removed.

 

In my case the fans are mounted on a thin gauge ali plate that is sandwiched in place by refiitting the cover. The fan plate can be removed by simply removing the top cover, unplugging the cable, and lifting it out.

 

Oh, the covers get easier to release with time.

Link to comment
Share on other sites

As discussed over the years with these caravan fridge installs it is always worth checking the air gap between the rear of the fridge and the inside of the caravan wall...Dometic spec is, I believe, is something between 10-25mm.

Anything greater than this should be addressed otherwise you may find any additional fan draught wont completely push the air over the evaporator/condenser.

 

Edited by charlieboy2608
Link to comment
Share on other sites

9 hours ago, D-Hill said:

I’ve ordered the parts ready for a test next week but probably some basic questions:

 

1. I’m planning on mounting two fans and sucking air out from the top vent,  do people install the fans behind  / inside the caravan or attach externally to the top vent?

 

2. I’ve attempted to remove the top vent, slid the clip up on the left hand side and the left hand side did come loose. The right hand side just won’t free, is there some method for removing the right hand side? I’ve tried carefully levering it, it’s as if the mastic has secured it but didn’t want to break the panel.

 

Subject to my tests next week, if successful I will probably install the fans behind and inside the caravan. I’ll attempt to drop a wire from the inside cupboard above the fridge and power the fan from one of the sockets in the cupboard (Phoenix+ 640). I may even 3D print some form of mounting bracket if needed.

 

 

I have written a “how to do it” for a Phoenix having done exactly that. If anyone else wants to fit a fridge fan to their Phoenix drop me a PM with your email address and I will email it to you (too big a file for a PM) 

 

 

Experience is something you acquire after you have an urgent need for it.

Link to comment
Share on other sites

Found my original and, having removed the pictures, the file is small enough to post.

 

As promised details of fridge fan installation. Please excuse me if some of it seems blindingly obvious but I am unsure of what you knowledge level is so I have tried to make it easy to follow and included everything. 

 

First off you will need

A 120mm 12v computer cooling fan (loads on eBay £5-8) 

An illuminated switch (so you don’t forget it’s on because you only need it when the ambient temperature is high) I would include a link to what I used but the link is about half a page long! Just search eBay for illuminated 12v switch. I used a small round rocker with a built in LED

Some push on spade connectors  

A few small zip ties (White is best so they aren’t obvious in use) 

Some thin electrical wire (I used speaker wire, the current is lower than minimal) 

A drill the same size as the switch body  (can’t remember the exact size).

A few screwdrivers

A couple of hours of your time

A bit of patience 

 

I chose to wire mine in the way I did for two reasons

1. When the caravan main power switch is off so is the fan so no chance if flattening the leisure battery.

2. There’s an easy 12v supply to tap into near where I mounted the switch! 

 

First up make sure the caravan master 12v switch is off! 

 

Then remove the top external fridge vent and secure the fan to the inside of it using the white zip ties through the fans mounting screw holes and the vent vanes. Make sure it’s the way round Mine was a fairly tight fit so make sure refit the vent before fully zip tying it in place. 

 

Once you have done that look into the space at the back of the fridge At the top corner nearest the outside wall of the caravan you will see a small space with some wires coming through it. You will need to feed your wire up through that space into the void behind the panel that holds the switches inside the caravan (but not yet) I used a length of stiffish wire and taped the cable to it and used that to feed it through the gap. 

 

Inside the caravan remove the bezel around the switches located above the fridge (it just pops off if you push one side outwards a little)  once the bezel is off there are 6 small Phillips head screws to remove. All of the switches will then fall forward along with the 12v plug in socket. 

 

Decide exactly where you want to mount the switch below the sockets and drill a suitably sized hole to accept it being pushed in. The panel is pretty thick! 

 

NOW you need to feed the wire up through the small gap into the void behind the switches and pull a bit through (work through the hole where all the switches were) 

 

Connect one end of the wire you have threaded through to the outer (return) terminal on the 12v socket along with another length and feed that length through the hole for the switch from the back (that’s 2 wires to the outer feed on the 12v socket one goes out to the back of the fridge, the other will go to the back of the switch) That wire is needed to allow the LED in the switch to illuminate when it’s switched on.( I think it’s the middle of the three terminals on the back of the switch but you need to check that) 

 

Now connect a length of wire to the centre connection of the 12v socket and feed that through the back of the panel. Fit a female push on terminal and fit it to the top terminal on the switch.Now connect the spare end of the wire you fed through from the back of the switch to the bottom terminal on the switch with a push on connector 

(Please check I have told you the correct terminals they are marked in some way) 

Return outside and make sure the ends of the wire you fed through aren’t touching. 

Switch on the caravans master switch, operate the rocker switch and the LED should come on!  If it does turn it off, return outside and connect the fan leads to the wire (just twist together for now and make sure they don’t touch. Switch everything back on and check the fan is blowing air outwards (if it’s sucking in just swap the wires over. NOW you can make a decent joint, just allow enough “spare” so you can remove the vent if you ever need to in the future. 

Push the switch into its hole, reassemble the switches, screw them back to the frame and fit the bezel.

 

Job Done! 

 

If you need any clarification (which I accept is quite possible!) please send a pm with a phone number.

 

It’s not a difficult job, you just need to approach it methodically. Once up and running you will be amazed how much more efficient your fridge is. If you put your hand near the fan when it’s running you feel just how hot the air it’s pushing out is!  You will find others that insist the fan should be on the bottom vent pushing air in but I have always fitted them as extractor fans. House fans don’t blow in they suck out!!

 

 

Experience is something you acquire after you have an urgent need for it.

Link to comment
Share on other sites

Very thorough write up MrPlodd!

Some PC fans have a variable speed (so a third wire) which needs to be cut off.

Link to comment
Share on other sites

3 hours ago, charlieboy2608 said:

Very thorough write up MrPlodd!

Some PC fans have a variable speed (so a third wire) which needs to be cut off.

 

:Thankyou:

 

I have tried one of those, it would only run at a very low speed, so I now use “2 wire” versions which run at a decent RPM  and shift a lot of hot air. 

 

I have contemplated fitting a fan on the bottom vent as well, but as the fridge works really well, even in hot temperatures, so I don’t see the need for an additional one, but at only a few quid I might just give it a go to see what, if any, further benefit I get. 

Experience is something you acquire after you have an urgent need for it.

Link to comment
Share on other sites

11 minutes ago, Mr Plodd said:

 

:Thankyou:

 

I have tried one of those, it would only run at a very low speed, so I now use “2 wire” versions which run at a decent RPM  and shift a lot of hot air. 

 

I have contemplated fitting a fan on the bottom vent as well, but as the fridge works really well, even in hot temperatures, so I don’t see the need for an additional one, but at only a few quid I might just give it a go to see what, if any, further benefit I get. 

Have you ever fitted the lower vent fan and/or upper vent fans onto the fridge insulation (as per dometic diagrams) so it blows over the condenser/evaporator as a comparison to fitting them directly behind the grills?

Link to comment
Share on other sites

In a word no! I have found an extractor fan fitted to the top vent improves the the efficiency of the fridge enough for me. In addition the cost is minimal in comparison to the ludicrous cost of the “official” kit. 

 

To my mind the important thing is to get the (already) hot air out from behind the fridge so cooler air is drawn in through the bottom so it can absorb more heat from the hot bit!

 

Probably best of the lot would be to have a fan blowing over the hot bit and then another on the top vent pushing the hot air  out. 

Experience is something you acquire after you have an urgent need for it.

Link to comment
Share on other sites

I've been doing some testing on the fans I have sitting in boxes in the garage. All have came from various computers over the last few years. I thought I had two prime candidates to use, 140mm so I thought they'd only run slow and use little amounts of power. So i set the pair of them up last night with three 18650 cells. They were tested and I know the capacity of all three are 2800mAh so a good match. I expected to leave it running for a few days to see how long they would last and then decide if it was worth wiring it into my caravan or just using these to keep it completely separate.

 

I got up this morning and the fans had stopped and batteries were flat, curious. So out came the voltmeter. Baring in mind both are Antec 140mm fans but different models, one has a physical switch for 2 speeds, the other 3 speeds. The 2 speed one uses 30mA on high and 20mA on low, about what I expected. The 3 speed one uses 140mAh on low, 190mAh on medium and the fuse for the high circuit in my voltmeter is blown so the high setting was well above the 200mAh limit!

 

That is a huge difference. So I would suggest you make sure whichever fans you end up with you either know from the spec sheet what the power draw is, or you test it. If I had used these, without testing, and wired it into my caravan, over the course of a 4 day long weekend offgrid, I'd have drawn 18amps. Not that large a figure, but probably not far short of the amount my TV would use.

Link to comment
Share on other sites

My fans, held on home made aluminium brackets and fixed to the plastic vent frame with 4mm rubber Rivnuts.

Automatic switching is done through a 10A 12v digital temperature controller with sensor thermostat and a separate on/off switch. The controller operates through a 12v automatic voltage stabiliser (recommended). The sensor is in the lower grille to measure incoming ambient air temperature. The fans are on at 32 degrees and off at 30 degrees.  All control parts from ebay (made in China).

The electrical feed is tapped into the fridge and cooker ignition circuit.

The rotary dial on the RM73XX fridge is left in the centre position and left to run automatically the fridge temperature remains at a constant 4 degrees even with temperatures in the mid 30's with very little noise from the intermittent operation of the fans.

John.

 

IMG_3179.JPG

Edited by John19
Link to comment
Share on other sites

With the help of this forum & Mr Plodd I've built (Beta version) a two fan version of the cooler and temperature sensor, still needs a little work and maybe I've over engineered it, could be a lot simpler to just cable tie the fans but I've enjoyed making it.

 

My biggest challenge is finding a suitable 12v power feed, my plan was to route a cable either up into the cupboard above the fridge or to the battery. However I may have found a better solution, the Dometic fridge appears to already be wired for a fan, see photo, does anyone know what type of connectors these are and where I maybe able to purchase them? Is this a good idea to connect a fan to these wires, I haven't checked to see if the wires are live or not?

Initial-Fan-Build.jpg

Dometic-Connectors.jpg

Edited by D-Hill
Link to comment
Share on other sites

Break out the multi-meter Jim and get testing! 

 

I bet the yellow is positive feed and the other is the return, they and will serve your purpose perfectly. 

Experience is something you acquire after you have an urgent need for it.

Link to comment
Share on other sites

Hi all, all very interesting regarding the various ideas so I set too and installed a fan half way up the back of the fridge, obviously to blow hot air out the top. As today was quite warm I tried it out to see how effective it was. After a short while HRH informed me that water was dripping on the contents of the fridge. Any ideas anyone as to why this should happen?

Cheers for now, Keith

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...