# Suck or blow: Fridge fan.



## erneboy (Feb 8, 2007)

Blowing air in from outside or sucking hot air from inside and blowing it out the vents? Also which will be more efficient to begin with and help it cool as quickly as it can, fridge vent on or off? 

It's been hot here and the fridge is having trouble keeping the temperature anywhere near low enough. Mind you people opening it without first thinking what they want and where it is has resulted in the door being open for minutes at a time. That hasn't helped either.


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## HurricaneSmith (Jul 13, 2007)

I'll be interested in this thread.

I recently saw an elegant solution where a pair of fans were mounted at the top vent drawing in air from the bottom vent and expelling at the top. But it was new and too soon for feedback from long term running.
.


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## Spacerunner (Mar 18, 2006)

I’ve mounted a single 80mm fan in the top vent to expel the warm air that gathers there.
Hot air is already finding its way to the top vent so the fan is only adding to the convection effect already happening.
Installing the fan at the bottom means the fan is having to push against a resistance.
Perhaps.....maybe.....sort-of.....IMO
So far it’s worked very well and got us through some very hot spells in southern Portugal.


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## eurajohn (May 9, 2005)

The normally accepted solution as being best is to have fans at top vents sucking air over the evaporator.

.


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## erneboy (Feb 8, 2007)

Thanks for that. Ours has only one vent at the bottom and a flue venting the top. It's an RV, perhaps that normal for RVs, can't say I've ever noticed. No points for me for observation then.

Anyway I can't mount it on the roof or in the flue so it has to be at the bottom. So I'm still wondering suck or blow and cover on or off. Thanks.


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## kabundi (Feb 14, 2011)

Removing the bottom grill will reduce the resistance to air flow and help the convection. At best the grill will have 50% open area so the resistance through that aperture will basically be halved with the grill removed. This will apply whether or not a fan is used.

If you do remove the grill make sure it is fully fixed in place again before you drive off or there is a chance of rain.

Just heard of someone on another forum who has been quoted €300 for a replacement grill after theirs fell off as they were driving after having it removed to help cooling.


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## powerplus (Oct 6, 2014)

hi ernieboy

i think the rv type fridge can have a fan in the roof vent

i did look into that a while ago when i was playing with my american travel trailer but i decided it was not needed even in portugal

im sure i was it on youtube

on our motorhome i have put 2 fans in the top vent and connected it up to a thermostat so it switches on and of automatically

top is best as heat is supposed to rise and the fans would remove the hot air and any fumes if there were any


i made a few setups for friends a while ago and everyone said they made a difference in portugal especially if the space behind the fridge is tight

barry


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## kabundi (Feb 14, 2011)

erneboy said:


> Thanks for that. Ours has only one vent at the bottom and a flue venting the top. It's an RV, perhaps that normal for RVs, can't say I've ever noticed. No points for me for observation then.
> 
> Anyway I can't mount it on the roof or in the flue so it has to be at the bottom. So I'm still wondering suck or blow and cover on or off. Thanks.


You probably can only access through the bottom vent so this will limit where you could fit a fan. In an ideal world you should mount the fan horizontally above the burner so that it is blowing air up the back of the fridge, however the clearance behind the fridge may restrict you to a very small diameter fan.

Your only practical option may be to fit three 100mm or more fans to the inside of your bottom grill. The fans should cover as much as possible of the face of the grill. In this case the fans will suck outside air through the grill and blow it around the base of the fridge which will pressurise the space and therefore force additional air upwards over the fridge cooling fins. Ensure that the fridge is properly sealed to the habitation area as putting the fans in this position has the potential to blow gas/CO into the habitation area.


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## erneboy (Feb 8, 2007)

Thanks Barry. I'll investigate that idea.


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## erneboy (Feb 8, 2007)

Thanks Kabundi, very informative. I'll do that because it's easiest.


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## kabundi (Feb 14, 2011)

Up until last week I had a single 100mm variable speed, temperature controlled, computer fan fitted to the top grill on my fridge/freezer. Last week when the ambient in Italy was in very high 30s I discovered that the freezer temperature had risen to -5 and the fridge temperature to +14.

I got two additional 100mm fixed speed fans from a local computer shop at €10 each and fitted them. The three fans have been operating 24/7 since fitment. I now have a freezer temperature of around -18 and a fridge temperature of around +8. It took about 3 days to get to these temperature and the ambient has also dropped a few degrees.


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## erneboy (Feb 8, 2007)

Ta Kabundi. Similar weather here in Spain just now. I've ordered two more fans, they'll come tomorrow. Very practical advice. I'm very grateful to you and all who answered.


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## dghr272 (Jun 14, 2012)

More fan power will help, I had used computer fans before but the fridge/freezer struggled at times here in Spain, fitted a 240v fan from a defunct tall fridge freezer, granted I have it on my top vent and it expels the hot air forcefully, but touch wood it’s fine in this years Spanish heat.

I know I’ve just jinked it haven’t I.

Terry


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## Penquin (Oct 15, 2007)

I fitted a twin fan above the fridge, blowing air OUT through the top vents, they are connected to a switch with off, on and thermostatic operation being available.

It works superbly, our thermostat is set to operate around 30C which we reach frequently.

I am not sure whether it should only be used on gas but we use it for EHU and gas and the result is excellent.

Some people have also fitted a small fan INSIDE the fridge to circulate the cold air inside.

There are threads relating to these fittings - a little research may help find them but I am not on a broadband so am limited n what I can do - sorry.


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## erneboy (Feb 8, 2007)

Thank you. I am aware of previous threads, but not of one answering the questions I had.

In any case the search facility is poor unless you can name the poster and get a couple of key words right.


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## raynipper (Aug 4, 2008)

I often thought about adding fans to my RV fridges but always found the excessive heat was short lived and never got around to it. But as you say Alan thinking and knowing what you are going to grab out of the fridge when it's very warm as well as having the fridge 'wall' away from the sun and even in shade helps enormously.

Ray.


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## powerplus (Oct 6, 2014)

morning all

1 have 120mm fans fitted in the top vent with a stat that switches on if the temp behind the fridge goes up to about 36c and off at 32c

this is about right and the fans do switch on and off every 5 minutes during the day and i do not have to worry about the fans needing switching off on a cooler day

on a very hot day they may be on most of the time but that is exceptional

1 thing to keep in mind is that the fans will reduce natural air flow if not switched on

i personally would not fit the fans in the bottom vent but that is my view



do you have the big rectangular roof vent on your rv ?


barry


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## erneboy (Feb 8, 2007)

Yes Barry. I'll have a look in there when it's a bit cooler and see what can be done.


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## Mrplodd (Mar 4, 2008)

I have fitted fans to about 5 leisure vehicles now, three MH’s And two caravans. I always fitted them to the top. My theory being to draw out the already hot air that had done its job so it could be replaced by cooler air that can absorb more heat from the coils.It seems to work OK. 

Andy


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## Penquin (Oct 15, 2007)

https://forums.motorhomefacts.com/182-electrical/54840-fridge-cooling-fans.html

https://forums.motorhomefacts.com/20-motorhome-chitchat/171649-update-fridge-vent-cooling-fan.html

https://forums.motorhomefacts.com/53-autotrail-motorhomes/117314-vento-fridge-fan.html

https://forums.motorhomefacts.com/182-electrical/161698-fridge-fans.html

https://forums.motorhomefacts.com/23-top-tips/108958-electricity-free-fridge-cooling-fan.html

https://forums.motorhomefacts.com/30-parts-accessories/187817-extra-fridge-fan.html

https://forums.motorhomefacts.com/182-electrical/116115-thermostat-control-fridge-fan.html

https://forums.motorhomefacts.com/4...46-fitting-fan-help-fridge-advice-needed.html

There is some bedtime reading for you, Mr Google does a much better job at searching MHF than the search engine on here does....

Just type into Google;

"Motorhomes facts forum fridge fans" and it brings up loads of direct links.

Always a better idea than trying on here !


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## jhelm (Feb 9, 2008)

Do you really think these fans make a difference. I have two mounted on the upper grill that blow out, I can feel the warm air going out, frankly I don't seeing making much difference. Maybe it is the type of frig. there aren't any exposed coils.


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## Mrplodd (Mar 4, 2008)

jhelm said:


> Do you really think these fans make a difference. I have two mounted on the upper grill that blow out, I can feel the warm air going out, frankly I don't seeing making much difference. Maybe it is the type of frig. there aren't any exposed coils.


A lot depends on the ambient temperature. In hotter climes (25°+ during the day) my experience, over a good few years now, is that a fan makes a huge difference. The higher the ambient temperature the greater the effect a fan system has. In colder climes (normal U.K. temps) it's nothing like as noticeable

All fridges, both domestic and leisure (absorption and compressor types) must have some system for radiating the heat into the atmosphere, without it they wouldn't work! If you take the external vent covers off and look inside you will see them, they must be there otherwise what is heating the warm air you can feel  ?

Andy


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## Penquin (Oct 15, 2007)

jhelm said:


> Do you really think these fans make a difference. I have two mounted on the upper grill that blow out, I can feel the warm air going out, frankly I don't seeing making much difference. Maybe it is the type of frig. there aren't any exposed coils.


Not a case of THINKING but KNOWING from personal experience repeated frequently every summer.

Our day time temperatures are regularly in the mid to high 30's and without the fans on the fridge struggles to hold a reasonable temperature even if switched to maximum on the dial. With the fans on and running on gas of course, we can turn the dial down about 90 degrees and the fridge maintains a cold temperature.

So experience has shown that the fans really do make a massive difference.


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## erneboy (Feb 8, 2007)

I now have three 120m fans sucking air in at the bottom. They are mounted away from and a bit above the burner.

I'll report back when I see how they perform.


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## GMJ (Jun 24, 2014)

Hi Al,

There was a big thread on this last year...

The bottom line is that both Dometic and Thetford state that any fans should be placed in the bottom vent blowing air up through the cavity which then expels out of the top vent. That way cooler air is flowing over the fridge fins.

Given that they make most of the fridges we all use I would go with their advice over random internet folks who will swear blind that putting it at the top is the best way!

Graham


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## jhelm (Feb 9, 2008)

GMJ said:


> Hi Al,
> 
> There was a big thread on this last year...
> 
> ...


Just saying that whatever goes out the top has to come in from the bottom. Though I suppose some comes in around the fans at the top.


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## Penquin (Oct 15, 2007)

GMJ said:


> Hi Al,
> 
> There was a big thread on this last year...
> 
> ...


I am not doubting you in any way, can you pin a link to that thread and / or the definitive Thetford/Dometic advice please ?

I am currently unable to find either and it is always good to read such things, sadly, I followed the advice of the Dometic kit that I purchased from Loisir 47 and it specifically said to mount in the top if possible, which is what I did. The Dometic kit cost me 39€ and does work well but it would interest me if their kit says the contrary thing to their advice.... :surprise:


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## dghr272 (Jun 14, 2012)

Penquin said:


> I am not doubting you in any way, can you pin a link to that thread and / or the definitive Thetford/Dometic advice please ?
> 
> I am currently unable to find either and it is always good to read such things, sadly, I followed the advice of the Dometic kit that I purchased from Loisir 47 and it specifically said to mount in the top if possible, which is what I did. The Dometic kit cost me 39€ and does work well but it would interest me if their kit says the contrary thing to their advice.... :surprise:


Best I could find was this post on a rather long thread.

https://forums.motorhomefacts.com/3...your-fridge-efficiency-lot-3.html#post2954442

Terry


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## Penquin (Oct 15, 2007)

Thanks, so the instructions for the genuine Dometic part that I fitted may well be accurate FOR THAT PART AND THAT PART ONLY.

Moral; buy genuine parts, not EBay and follow the instructions carefully,mfailure to follow such instructions could have serious consequences if something goes wrong and your insurance company remain unconvinced by your "I followed what they told me on MHF, guv."


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## Mrplodd (Mar 4, 2008)

Well I bought a computer cooling fan off eBay for about a fiver, plus an illuminated switch. Those two combined with a bit of wire, a fuse, 4 zip ties and about an hour of my time does the job for me! 

I am more than happy that I have done a decent job (at least four times now) for an awful lot less than Dometic wanted for a cooling kit. My system (fixed to the top vent) does exactly what I want it to do. It sucks hot air out of the fridge space, it is in a different location to that recommended by Dometic but, in hot weather, it makes my fridge a lot more efficient than it was without the fan.

I am certainly not worried about anything my insurance company MIGHT say. People fit electrical “extras” to their vehicles all the time!! 

Andy


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## Pudsey_Bear (Sep 25, 2008)

kabundi said:


> You probably can only access through the bottom vent so this will limit where you could fit a fan. In an ideal world you should mount the fan horizontally above the burner so that it is blowing air up the back of the fridge, however the clearance behind the fridge may restrict you to a very small diameter fan.
> 
> Your only practical option may be to fit three 100mm or more fans to the inside of your bottom grill. The fans should cover as much as possible of the face of the grill. In this case the fans will suck outside air through the grill and blow it around the base of the fridge which will pressurise the space and therefore force additional air upwards over the fridge cooling fins. Ensure that the fridge is properly sealed to the habitation area as putting the fans in this position has the potential to blow gas/CO into the habitation area.


If you put so many fans in then the fridge may stop altogether, or maybe even overcool, it's a fine balance getting the airflow just right, one fan at the top is best and blowing out, covers all off to help natural air flow, to put fans at the bottom to pressurise the space may allow air to be blown into the hab area.

@alan, do you have a chimney in effect rather than a rectangular top vent in the side of the van? if so you should still be able to fit a fan horizontally if you can get good enough access, maybe by pulling the fridge out of it's housing.


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## Mrplodd (Mar 4, 2008)

If you fit a fan to the top vent (as I have done for many years/vehicles) then there is no chance of "over pressure") forcing any fumes into the habitation area and will, as I pointed out earlier, draw out air that has already absorbed heat from the fridge cooling fins and pull in cooler air via the bottom.

This merely enhances the convection current that is already operating between the two vents _without_ any of the problems of (possibly) pushing fumes into the habitation area.

I use a computer fan with its own heat probe/sensor. The hotter it gets in the fridge compartment the faster it spins so the more air it shifts !

In an ideal world I would probably fit one fan blowing onto the cooling fins (as per Dometic kits) and another on the top vent to suck the hotter air out. However my single fan cost me less than a tenner all in and the Dometic kit costs four to five times as much!

Andy


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## erneboy (Feb 8, 2007)

My fridge is back to working normally.

I fixed three of these fairly weak fans to the inside of the bottom vent: https://www.amazon.es/gp/product/B00ZW15B6U/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

Thanks for the advice. I'm happy with the above solution.


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## trek (May 1, 2005)

I wouldnt blow in case it disturbs the flame on the burner


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