Fridge fan installation ... DIY info please (1 Viewer)

[Lenny HB]

OK, tempting fate here. Why is there a need for an expensive fan controller for fans mounted behind the top fridge vent? I bought 2 Arctic computer fans - which are indeed almost silent - and connected them to an existing permanently live feed to the fridge. They are connected with a 0.5amp inline fuse, the feed then going through a cheap temperature switch, a 35 degree normally open type, mounted up high behind the fridge.



You have no control to manually turn it off and on, but why does that matter? If the fridge is running you want the fans to be ready to come on anyway, they'll come on when it gets to 35 degrees above the back of the fridge, inside the vent.

If the fridge isn't running and the side of the van gets hot enough in the sun to turn the fans on, who cares? They use next to no power and my solar panel will easily cover the consumption in that heat. Living in the UK the chances of my van reaching 35 degrees are remote anyway! I've had it like this for a year now and it seems to work well.

Am I missing a downside? Just seems a simple, easy and cheap way to add fans and wire them in. You could use a different switch if you wanted a different temperature, they are after all only a couple of quid.

Those are pretty useless they have a 15 deg hysteresis, so effectively the fan will run all the time as they will never get cool enough to turn the fan off might as well just have a manual switch.
Also they are the same price as the cheaper PCB controller.

 

[Lenny HB]

Update on my loaded up fridge.

The freezer had 48 ¼lb burgers and 32 sausages in it but that won't make much odds as the freezer is a slave to the fridge.
The fridge had 18 bottles of wine and food crammed into the top and bottom.

Outside temp was 16 deg, and while juggling to get it all in fridge temp rose to 15.
The internal fan was running but external fan controller was turned off as it was only 16 deg outside.
After a couple of hours the internal temp was about 11, switched the controller on and temp above the coolant fins was 40deg so fridge was working hard considering it was only 16 outside.
After a couple of hours with the external fans running fridge down to 6, and overnight dropped to 3 deg. I was measuring temp ⅔ of the way down the fridge in the centre of the shelf.
Monitored it for a couple of hours in the morning, min 2.9, max 3.3.
Well pleased considering how loaded it was. Obviously won't get that sort of performance in 30deg plus, but pretty good result.

Forgot to mention only achieved 3 deg after I turned the fridge up to max (5 bars).

 

[Stewart J]

OK, tempting fate here. Why is there a need for an expensive fan controller for fans mounted behind the top fridge vent? I bought 2 Arctic computer fans - which are indeed almost silent - and connected them to an existing permanently live feed to the fridge. They are connected with a 0.5amp inline fuse, the feed then going through a cheap temperature switch, a 35 degree normally open type, mounted up high behind the fridge.



You have no control to manually turn it off and on, but why does that matter? If the fridge is running you want the fans to be ready to come on anyway, they'll come on when it gets to 35 degrees above the back of the fridge, inside the vent.

If the fridge isn't running and the side of the van gets hot enough in the sun to turn the fans on, who cares? They use next to no power and my solar panel will easily cover the consumption in that heat. Living in the UK the chances of my van reaching 35 degrees are remote anyway! I've had it like this for a year now and it seems to work well.

Am I missing a downside? Just seems a simple, easy and cheap way to add fans and wire them in. You could use a different switch if you wanted a different temperature, they are after all only a couple of quid.

As Lenny has said your fans will be running constantly, have just fitted a similar system to his. Road tested this weekend on a rally no ehu so fridge on gas, ambient air temperatures during warmest part of day 17-20 degrees, surprising to see how hot it gets at the top of compartment, from 24 upto 35-37 within minutes of fridge firing up. I initially set my controller differential to 2 degrees but this I had to readjust to 4 to stop cycling.

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[Lenny HB]

As Lenny has said your fans will be running constantly, have just fitted a similar system to his. Road tested this weekend on a rally no ehu so fridge on gas, ambient air temperatures during warmest part of day 17-20 degrees, surprising to see how hot it gets at the top of compartment, from 24 upto 35-37 within minutes of fridge firing up. I initially set my controller differential to 2 degrees but this I had to readjust to 4 to stop cycling.

Just proves what I have said before that different installations need different settings, 2 deg deferential works fine on mine. Last van with same fridge almost identical installation turn on temp was set to 35, on this van to get the same results I've had to set it to 32.

 

[MitchandJenny]

NEARLY ready to start installing 2 PC fans and a chinese temp controller.
But MUST finish the folding solar panel wiring FIRST ! ! !
Oooooh Betty ! ! !
Busy this retirement lark isn't it.
Thanks to all for info.
Mitch.

 

[Richard n Ann]

Reading the specs of these digital controllers I found they actually use as much power as the fans themselves. Much better to make your own or use a mechanical thermostat.

It's obviously no problem if you're on hook up all the time mind.

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[Richard n Ann]

This is my electronic thermostat. It uses zero power when the fans aren't running and really simple to build.

 

[jessthedog]

View attachment 177544
This is my electronic thermostat. It uses zero power when the fans aren't running and really simple to build.

It looks simple!!!

 

[Poutie57]

I've just finished installing my external and internal fans following Lenny's way of doing them and they work perfectly and relatively easy to do so a big to him for sharing his experiences

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[Feltwell]

Those are pretty useless they have a 15 deg hysteresis, so effectively the fan will run all the time as they will never get cool enough to turn the fan off might as well just have a manual switch.
Also they are the same price as the cheaper PCB controller.

I've yet to take the van to properly hot climes since fitting it, but I have noticed it cut in one time on a hot day in the UK with the sun on the side of the van. It cut out OK, but I can believe they have a large hysteresis.

I can see digital PCB controllers being a bit of a pain, do they not reset every time they loose power? Is one like this a better bet, although I'd have to see if I could disable the "power on" light to stop it using some power all the time. Electronics, beyond basic installations, fault finding and fixes, aren't really my thing! I can't see me building one like Richard and Ann's, although I admire him or her for doing that!

 

[Stewart J]

I've yet to take the van to properly hot climes since fitting it, but I have noticed it cut in one time on a hot day in the UK with the sun on the side of the van. It cut out OK, but I can believe they have a large hysteresis.

I can see digital PCB controllers being a bit of a pain, do they not reset every time they loose power? Is one like this a better bet, although I'd have to see if I could disable the "power on" light to stop it using some power all the time. Electronics, beyond basic installations, fault finding and fixes, aren't really my thing! I can't see me building one like Richard and Ann's, although I admire him or her for doing that!

The digital controller Lenny linked to (and I also fitted) does not lose its settings when power lost or it is switched off. You can also switch off the controller when it's not needed it has its own power off button and built in relay.

 

[LesW]

Why not just have an on/off switch?

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[Feltwell]

The digital controller Lenny linked to (and I also fitted) does not lose its settings when power lost or it is switched off. You can also switch off the controller when it's not needed it has its own power off button and built in relay.

Great information, thanks Stewart.

 

[LesW]

Why not just have an on/off switch?

Anyone...?

 

[funflair]

Anyone...?

You don't need it on all the time and on/off can't run the fans at different speeds.

Martin

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[LesW]

You don't need it on all the time and on/off can't run the fans at different speeds.

Martin

Thank you.. I have two fans on order and was wondering why.

 

[Stewart J]

Why not just have an on/off switch?

High temperatures behind fridge impact it's efficiency an on/ off switch does not answer the problem and one would need to install a remote temperature probe to monitor this so an auto system is the obvious answer. But Lenny and others including myself are not trying to sell you a system or solution just offering advice, your choice.

 

[LesW]

Thanks for that Stewart.. I'll have to have another read through the thread to see what controller to get.. (and how to wire it up).

I was intending to just switch the fans on and off depending on the outside temperature.

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[Stewart J]

Hi Les, since fitting the controller and being able to monitor the temperature in the upper area of the compartment behind the fridge I was quite surprised at how quickly the heat builds up when fridge on gas, it will be interesting to compare when we are on ehu (later this month in Spain) and see how the fans and fridge copes with higher ambient temperatures. Earlier in year fridge really struggled in Portugal everything in freezer softened.
Link to controller many of us have fitted thanks to Lenny research follows, but search around it varies in price. ATB
http://www.ebay.co.uk/itm/10A-12V-D...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

 

[MitchandJenny]

Hello Mel (Minxy girl)
I'm sure John Laidlaw posted a picture of the same thermostatic controller as I'm going to use.
But I can't now find it in the thread. It cost £1.29 and came in a week.
Wired it up to an old spare battery I had and it worked VERY well..
Just got to install it all now.
I'm a bit "useless" at the moment, got a water infection.
I WILL be back. x
Mitch.

 

[MattR]

Our fans are running really well - in the circumstances (cool, cloudy weather), almost too well. What is the best way to reduce the fans' speeds so that they are slightly quieter (Arctic fans) and shift less air so that they don't keep switching on and off so often?

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[Richard n Ann]

Our fans are running really well - in the circumstances (cool, cloudy weather), almost too well. What is the best way to reduce the fans' speeds so that they are slightly quieter (Arctic fans) and shift less air so that they don't keep switching on and off so often?

Wire them in series so they only get 6v each. You can put a series /parallel switch on them to switch between half and full speed.

 

[Gellyneck]

Our fans are running really well - in the circumstances (cool, cloudy weather), almost too well. What is the best way to reduce the fans' speeds so that they are slightly quieter (Arctic fans) and shift less air so that they don't keep switching on and off so often?

You could use something like this.

 

[MattR]

Wire them in series so they only get 6v each. You can put a series /parallel switch on them to switch between half and full speed.

I can't find a circuit diagram for a series / parallel switch. How would it work please?

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[Richard n Ann]

You could use something like this.

This would be more efficient;

https://www.ebay.co.uk/i/1911406763...3D710-134428-41853-0%26rvr_id%3D1280558982435

 

[MattR]

You could use something like this.

Would that work on 4? Wire fans?

 

[Richard n Ann]

Easy

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[MattR]

This would be more efficient;

https://www.ebay.co.uk/i/191140676364?chn=ps&dispItem=1&adgroupid=13585920426&rlsatarget=aud-295856145004la-142405555266&abcId=&adtype=pla&merchantid=6995734&poi=&googleloc=9046379&device=m&campaignid=207297426&crdt=0&ul_ref=http%3A%2F%2Frover.ebay.com%2Frover%2F1%2F710-134428-41853-0%2F2%3Fmpre%3Dhttps%253A%252F%252Fwww.ebay.co.uk%252Fp%252F12v-40v-10a-Pulse-Width-Modulator-PWM-DC-Motor-Speed-Control-Switch-Governor%252F504453671%253Fiid%253D191140676364%2526chn%253Dps%2526dispItem%253D1%26itemid%3D191140676364%26targetid%3D142405555266%26device%3Dm%26adtype%3Dpla%26googleloc%3D9046379%26poi%3D%26campaignid%3D207297426%26adgroupid%3D13585920426%26rlsatarget%3Daud-295856145004%3Apla-142405555266%26abcId%3D%26merchantid%3D6995734%26gclid%3DEAIaIQobChMIyqj3ssbN1QIVBrXtCh2YWgz7EAQYASABEgL5cfD_BwE%26srcrot%3D710-134428-41853-0%26rvr_id%3D1280558982435

That would allow a wide range of fan speeds? Seems great.

 

[MattR]

View attachment 179307
Easy

I wish I understood it.

 

[Leltel]

I brought fridge fans 3 months ago still sat in the MH garage
Tel keeps saying he will fit them, maybe next year

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