fridge thermo fan wiring/thermostat questions

[vicszd30]

Howdy all, I have a 25 yr old Jayco Camper with ye' ol 3 way fridge in it. The fridge works oook but....
I have brought in a new heavy 12v supply cable to the fridge to replace the hair string Jayco use so that's made it preform much better.
Would you believe the gas and 240v still works too "wow a little win"

Anyway the way jaco have it set up the hot air "and yes it gets hot" vents into the camper. so hot it heats the bench on top of it .
I have heard "some" install those computer fans to the back of the fridge to move the air over the elements and vent the heat outside the camper.. good idea -so I went the one better and fitted a 400mm thermo fan with a pcm speed control switch/dial and volt meter so I can run the fan at any amp I want- even at .5 of an amp "it's a 7amp fan" the fan draws danm well- so well the fridge is it it's lowest setting and still freezing my lettuce
My thought with using such a large fan is I can crank it up to full amp and use it as a exhaust fan if I have to cook inside- cool huh! Plus there is now way those computer fans can move as much air as this fan for the same power use.. Can anyone tell me how much those fan use "power wise"?

Now the thing is I am not a rich man and cant afford a auto sparky and have struggled through with what I can regarding the wiring, Wiring in a fan and a switch with fuse is about my strength and I would like to hear from anyone that may direct me on the right path on how to wire in a "thermostat control switch" that I can set to come on and off when the fridge is heating up and also another switch I can use to over-ride that ,so I can turn the fan on and up in speed to use as an exhaust fan..
I will post some photos tomorrow of the camper/fan so far- but here is a very well priced "thermostat control switch" I found on flea bay.. http://www.ebay.com.au/itm/221521374020

I also found this so I can find out where on the fridge pluming to install the "thermostat reader" ! The beauty of this control switch is you could put it where it's hot to touch then just adjust the control settings on the unit...
I just want to have a play with it - be interesting to see what the intercooler pipes are doing etc... http://www.ebay.com.au/itm/361336821842

I'm guessing I will need to use "relays" and that's where I run short on knowledge so if anyone has ANY suggestions on how to go about this please feel free to draw me a pic/diagram

Once again thanks and have a great cup day... cheers vic

 

[Oldie]

Hi Vic,
Glad you asked this question. I've just bought a 1993 model jayco penguin with a 3 way fridge.
I never thought about the heat outlet. It'll be interesting to see what answers you get.
cheers

 

[vicszd30]

Hi Vic,
Glad you asked this question. I've just bought a 1993 model jayco penguin with a 3 way fridge.
I never thought about the heat outlet. It'll be interesting to see what answers you get.
cheers

Oh cool Oldie, mines a 90's lark ! Guy that I got it from had a special order done so the layout is different .. one owner.. done some miles though. I did brakes, 6 stud hubs and rims, strengthened the sub frame. lengthened the draw bar, made alloy box's etc, seeled of the lower door. gave it a coat of white enamel with stripes woo hoo lol , and then there is all the battery and dc works..

Getting back to the fan though, it works a treat oldie, no shite! I am going to fit a little fan inside the fridge also to help circulate the air off the freezer element. I read that it works wonders too.

I'm hoping 'ol tony might chime in on this one- I cant believe there not one auto sparky amongst us here danmit! lol
cheers vic

 

[happy john]

G'day Vic, I had 2 fans with a simple switch powered from the 12 volt supply to the fridge, it worked very well also had an internal fan to circulate air that was wired via the water drain pipe. I would just turn the fans on when it was hot, never bothered with a thermostat the tiny amount of power used was not an issue. Have a look at this link, it may help a bit.
http://www.dreampod.net/boroma/fridgefan.html

 

[vicszd30]

G'day Vic, I had 2 fans with a simple switch powered from the 12 volt supply to the fridge, it worked very well also had an internal fan to circulate air that was wired via the water drain pipe. I would just turn the fans on when it was hot, never bothered with a thermostat the tiny amount of power used was not an issue. Have a look at this link, it may help a bit.
http://www.dreampod.net/boroma/fridgefan.html

I think I have to much time to myself Happy Yeah your right- it uses bugger all power at .5 to 1 amp, am I right in thinking that's per hour?

I like the internal fan trick- very clever. I found a few el'cheapo's on fleabay and one has a light in it lol I like the light

If wiring in a thermos switch and over-ride switch is to hard I may just stick with the manual on off , It's the turning off of the thermos switch when I hit the over-ride that has me! I may have to pay an auto sparky to draw me up a plan ..
Cheers for the link I'll take a look. vic

 

[happy john]

Remember the 3 way has been around forever and the biggest issue is incorrect installation and wiring. I'm guessing yours is a Dometic RM2350, if the bench on top is hot it's just placed in the spot with no insulation. Improve this by stuffing fire retardant insulation around the cabinet filling any gaps, you can do this via the top and bottom vents.

Most are wired to the house battery for 12 volt whilst travelling and an anderson plug to maintain charge on the battery and power the fridge. This is not good enough, you need a direct feed from the alternator to the 12volt terminals with at least 8mm cable via a VSR with circuit breakers front and rear.

The charge to the house battery should be a seperate cable and anderson plug wired in to parallel with the tugs aux battery, this way when you check the voltage at the fridge terminals via the bottom vent it should read well above 12.2 volts in operation and the house battery is getting full charge too.

Lastly get some of those self adhesive hooks and rig up some shade for the van's wall behind the fridge, this helps heaps. The only other thing is in hot humid conditions whatever you do they will still struggle, having a compressor fridge as backup and keeping high risk items such as meat and dairy in that is a wise choice.

 

[vicszd30]

Remember the 3 way has been around forever and the biggest issue is incorrect installation and wiring. I'm guessing yours is a Dometic RM2350, if the bench on top is hot it's just placed in the spot with no insulation. Improve this by stuffing fire retardant insulation around the cabinet filling any gaps, you can do this via the top and bottom vents.

Most are wired to the house battery for 12 volt whilst travelling and an anderson plug to maintain charge on the battery and power the fridge. This is not good enough, you need a direct feed from the alternator to the 12volt terminals with at least 8mm cable via a VSR with circuit breakers front and rear.

The charge to the house battery should be a seperate cable and anderson plug wired in to parallel with the tugs aux battery, this way when you check the voltage at the fridge terminals via the bottom vent it should read well above 12.2 volts in operation and the house battery is getting full charge too.

Lastly get some of those self adhesive hooks and rig up some shade for the van's wall behind the fridge, this helps heaps. The only other thing is in hot humid conditions whatever you do they will still struggle, having a compressor fridge as backup and keeping high risk items such as meat and dairy in that is a wise choice.

Good points. And onto the "shade cloth trick " too -thanks happy.

*
My mistake the fridge is on 240v at the moment- yet to fit up the 12v to the AGM..
It works on 12v well running the battery directly to the fridge on a test fit up..


What I did was run a new direct 12v feed to the Ctek then to the AGM battery, the plan is to wire the 12v feed to the fridge from the AGM?? Any thoughts?
The only things running off the AGM battery at the moment are the fridge exhaust fan, battery box light "when needed", the inverter when needed for phones and lap top, x2 "car interior led lights" a mtr of light strip and the water pump!
I thought this was better than running the 8mm from the ball and plus the Ctek will charge the AGM at the right rate and manage the solar panels to their best...
You know that thermo controller uses 3 to 4 amps ... derrrr I missed that bit!
It's manual on/off if I cant work out how to use that thermostat I got from Jcar.
cheers vic

 

[happy john]

Yeah the 12 volt idea you have is ok and similar to what i used with mine at first, just remember those fridges draw up to 15 amps on 12 volt the poor house battery will take a while to recover with the fridge drawing most of the juice. Having solar whilst camped with the small appliances you are using should mean no drama's.

 

[Old.Tony]

I'd never wire the 12V of a 3-way fridge to the house battery. There are two main reasons for this:

1) It draws LOTS of power. 15A is a small fridge. The fridge in my van draws around 30A.

2) The 12V circuit does NOT use a thermostat. The 240V and gas methods both use a thermostat.

Both of these issues are because the 12V operation was only designed to maintain the coolness while you were driving (power supplied by the car alternator). In a free-camping scenario (no power) the intention is to use gas to run the fridge while camped.

In my own caravan, I've cut the 12V input to the fridge and connected that to an inverter. I've plugged the 240V cable of the fridge into the inverter. While I'm driving, I'm sending a little more power (about 38A) to the 600W inverter, but it's driving the fridge with a thermostat which in my opinion is better for the contents, especially if you want to stop in a rest area in the middle of Australia and grab a coldie.

How about the heat in yours ... it needs to be evacuated once it's done its work, but don't worry about where it's hottest - there's 2 heating elements and a gas burner that produce heat exactly where it needs to be. There should be a tube that rises and connects to the upper vent to allow the raw heat out.

There's other heat, coming off the fins in the rear. There are TWO things to do here that are essential. Both depend on the fridge having a lower and an upper vent. If you don't have both, we'll need to re-think things. Standard setup is with two vents so let's look at that for now.

First, insulate above and on the sides of the fridge. Ordinary polystyrene foam is good enough. Don't let it sit too close to the burners (because foam is highly flammable) but try to make sure that the upper area (from about a third of the way up, all the way up and over) is nicely insulated.

Second, grab a pair of computer fans, strip the crap off them and look at the wires. There should be a red, black and yellow wire. Cut the yellow one into tiny, tiny pieces and use them at the next wedding you attend. Mount the fans on the UPPER vent so that if the vent is lying down with the outside face on the table (and you're looking at the inside face) place the fans on top with the cables coming out from the underside, so the fan is uppermost. Cable tie into place, or any semi-flexible adhesive except hot glue. Now join the two red wires together, and the two black wires together.

Right, the easiest way to power them is to have a switch somewhere inside and when it's too hot outside or you feel the fridge is struggling, turn the fans on. Run negative up to the black wire, use a little terminal joiner and that's done. Run positive power to the switch, then from the other side of the switch to the red wires. Finished! Put it all together and enjoy. That's how our previous caravan was done and it doesn't work too badly.

What we DID find was that the older fridges couldn't handle desert heat. We had a night where at 3am it was still mid-30s (I think it got down to 33C during that night). The fridge hated it. The newer fridges are "Tropical" rated, meaning that they can drop the temperature down to something like 40C below ambient. The old one we had in our Future Systems caravan could manage 25C at best - imagine, it was 33C that night - our milk was pretty sordid by the time we got back to civilisation! Insulating it and adding those fans will help, but if the fridge can't do any better than 25-30C below ambient, then it's not going to do what you want in the peak of summer and that's when you're either going to look at a portable electric cooler (which uses say about 3A per hour) or trying to grab a tropical rated 3-way.

 

[vicszd30]

Wow- danm! Tony- thanks for that! Thing is fella I have installed the thermos fan already!

Good point on when and where to use gas 12v... Do you think what I have done will work- use the new feed to the ctek then to battery "whilst towing" and then gas for camping and obviously 240v where I can???
So I would be better off running it off the inverter than the house battery?

 

[vicszd30]

Yeah the 12 volt idea you have is ok and similar to what i used with mine at first, just remember those fridges draw up to 15 amps on 12 volt the poor house battery will take a while to recover with the fridge drawing most of the juice. Having solar whilst camped with the small appliances you are using should mean no drama's.

I never knew that - 15amp! wow! I guess it's trial and error as I go but your help guys is priceless..
Tony's idea of running it off the inverter is worth a thought.
What are you and how are you doing it now happy?

 

[Old.Tony]

I only use the inverter while on the move, the inverter gets is power from the car. My fridge is never, ever connected to the house battery. On the thermostat it will be kinder than on 12V, which will draw 15A constantly. Over 10 hours that's 150Ah. Not only do you need a big battery to handle that, but a huge solar array to put it back.

 

[Oldie]

I'm lost with all this tech talk LOL.
The 3 way fridge I've got is a dometic (I'll have to check the model) and only a year old.
What can I expect if I mount a solar panel on the roof of the van so the fridge is constantly running on that. I assume it would be running on 12V all the time.
Cheers

 

[happy john]

I'm lost with all this tech talk LOL.
The 3 way fridge I've got is a dometic (I'll have to check the model) and only a year old.
What can I expect if I mount a solar panel on the roof of the van so the fridge is constantly running on that. I assume it would be running on 12V all the time.
Cheers

The 12 volt is ONLY for when you travel Cliff, even if you had enough solar power a few hours after dusk the battery would be flat. If you read page 1 the correct way to wire it up with the 2 anderson plugs is the optimal way.

 

[happy john]

I never knew that - 15amp! wow! I guess it's trial and error as I go but your help guys is priceless..
Tony's idea of running it off the inverter is worth a thought.
What are you and how are you doing it now happy?

I am "vanless" at the moment but in the last 18 months I was using the inverter method as Tony describes. Early on when I would travel on 12 volt we went from Brisbane to North Rockhampton about 700kms non stop everything was starting to freeze. This was obviously due to no thermostat and the fridge didn't know when to stop.

 

[vicszd30]

Ahhhh ok got it ! I'll go inverter also for traveling also me thinks. Thanks Happy

Tony- that temp sensor I got for Jaycar seems to be an open circuit when cold "I hooked up a test light and the light came on" and then must close when it gets hot enough.. So how the hell do I get that to work?? lol
There must be a solenoid/relay?? One that once the feed stops it -it then turns on the other supply "connection to the fan"...
Thing is I don't know what to even google lol ffs I'm lost ! Got me thinking though! cheers Vic

 

[Old.Tony]

That's an easy one. The temp sensor has a number of wires and here's how I'd hook it up. Lie i down so the terminals are closest to the table and the front is facing away from you. Terminals are numbered 1 through to 7.

Terminals 6 and 7 are for power. The picture on the top will tell you which way to hook it up (positive/negative).

Terminals 4 and 5 are for the temperature sensor probe and it really doesn't matter which way you hook it up.

Now it's fun time and really, it's not hard to handle. Pin 2 should be your power supply (if you're switching positive to a fan and the other side of the fan is connected to negative, then this is the positive feed from the battery). Pin 1 or pin 3 are the outputs. It is a relay already - although it's only rated for 5A, you won't be using a fan that draws 5A (I hope!). Connect Pin 1 to the fan. As the temperature rises, the relay should switch on, the fan should start and continue running until the temperature falls below a certain level (programmable, I think).

 

[vicszd30]

Umm sorry Tony I think your talking about the control box where you set the temp. I think that uses up to 3amp so not going that way.
What I am wanting to set up is one of these -

 

[vicszd30]

Ha - ok ok I was sold the wrong switch ! The one that was sold to me was a "closed" thermostat and from what I have read that means a current will pass through it until it hits the heat range and then trows out! For hot water heaters etc

The one I need is a "open" thermostat that doesn't allow a current through until it hits the set heat range- these switches come at 50deg 70 deg and 100deg ..
These are as simple as putting in line - I imagine it would go on the earth wire?? any thoughts?

Oh and no Tony I wouldn't be running it that high and if I did it would be just to suck the cooking fumes out of the camper for a minute or two.. I would set it at about .5 to 1amp as that moves plenty of air over the elements ...

I'll keep you posted- waiting to hear back from Jaycar regarding availability !

 

[happy john]

That manual switch is looking more appealing now Vic