Digital of and on Thermostatic temperature control unit. (1 Viewer)

[MitchandJenny]

I recently bought one of the above, so that I could connect 2 computer fans to it, to mount behind the the top vent of the fridge.
It has 3 screens, one on the left for the temp to switch on at, one in the middle to show ambient temp, and a third on the right to show what temp it will switch off at.
I have connected to a supply and all 3 screens functioned ok.
I connected my 2 (tested) PC fans to the output but zilch.
I have verified the input is good, but cannot get anything out of the output side ! ! Despite adjusting the start and stop temperatures to settings that should cause the thing to operate.
Have I wasted my £1.29p..
OK I KNOW thats a ridiculous price, but there are loads of them out there at roughly the same price.
Have I missed something ? Come on you "wiz-kids" Help ! !
Mitch.

 

[berni109]

What are the connections? Is there a block with more than 2 connections?
Or post an eBay link

 

[TheBig1]

the connections are 12v plus and ground. the other 2 are a normally open relay contact, so no power goes to the switch terminals

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[Camping Gaza]

Have I missed something ?

Yeah.... what the heck is "one of the above"? how about a link or a picture?

 

[berni109]

So this is how I would wire it.
12v + and - marked on the thermostat to van hab battery which will power the thermostat.
Also Connect 12v + above to right hand relay connector.
Connect left hand relay connector to + on fan.
Connect - on fan to 12v - as above on the thermostat.

 

[MitchandJenny]

Sorry about the vagueness Gaza and Berni109. If I could post a link of it I would mate. But I now can't find one like it on Ebay. Mine has 3 digital screens.
Big1, I have a terminal block on the left which has a pos and a neg, to which I have connected a live feed.
I am EXPECTING to see a switched feed coming out of the other 2 terminals on the right, when the "start" thermostat (on the left) clicks on, and to lose it again when the "stop" temp (on the right) is reached..
I wish I could post a link, but all the others I find, have only got the 1 screen.
I take your point about the "normaly open" output, but the thermostat should close it yes ?
Mitch.
PS. I may of course, have a "duff" one.

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[DBK]

This may not help as it is a different temperature controller but it might have similar connections to yours.

If we number the terminals from the left as 1, 2, 3 and 4 there function is:

1 and 2 are connected to the relay contacts which close when the set temperature is reached.

3 is the +12 volt feed.

4 is the - 12 volt feed.

I connected the fan by putting the fan negative wire to terminal 4. Then connect the fan positive wire to terminal 2. Finally connect terminal 1 to terminal 3 with a short jumper lead.
The 12 volt power feed is then connected to terminals 3 and 4 and away it goes.

It might have been neater to swap the connection of fan and jumper on terminals 1 and 2 but that's just the way I did it.

Warning! The above is from memory and the polarity of 3 and 4 may be the other way round - check before copying.

 

[berni109]

As I said above and described by @DBK you have to put 12v power into the relay.
The thermostat will power the relay on and off from the connection to the hab battery. But u need aanother 12v feed into the relay and out of the relay to the fans.

 

[MitchandJenny]

Thanks DBK and Berni109.
I'm off to try that now.
Mitch.

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[berni109]

View media item 22236Simple diagram much easier than a discription. Not your connecting block but hope it helps

 

[MitchandJenny]

Yipee ! ! ! !
Many thanks DBK.
I hadn't put a jumper to feed the relay...... Doh.....
I set it to cut in 25 and cut out again at 23.. Which I can adjust when I've tried it on the van, as this was just a bench test.
Checked it by putting the probe in my mouth to warm it, then blowing on it to cool it down again.
Just got to work out a neat install now.
I think I will put the "gizmo" in behind the lower vent where its coolest (and where there is a permanent 12volt feed) and mount the 2 fans behind the top vent where all the heat builds up.
I'll have a go when the better weather returns.
Thanks again you all for your input.
Mitch. xx
Some clever folk on here.

 

[Diabalo]

I fitted the exact one a couple of weeks ago out here in France, I have set the fans to come on at 35degs, it's going most of the day and night, only Cools down enough in the early hours to shut them off but it's made a big difference to the fridges performance.

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[Stretto Boy]

Not all fans require a digital temperature control unit. What they lack in electronic sophistication they make up for in simplicity and reliability.

 

[MitchandJenny]

My lovely lady has a selection of those....
For her "power surges" ! ! !
Time of life and all that.....
Mitch.

 

[MitchandJenny]

Diabalo.
Has it meant that the fridge is not "on" and using gas as much as it used to ??
Our problem was that the fridge was working SO much of the time, and of course the gas being burnt, just added to the heat build-up problem behind the fridge.
Still thinking about the wiring loom set up I will use to install mine.
I'm a "bit" OCD and a fussy arse who hates doing a job twice, just because I didn't think about it enough in the beginning. So things 'take time' to come to fruition nowadays.
A VERY far cry from how I used to be as a WO 1 in the military.
Hey ho, time passes....
Mitch.

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[MitchandJenny]

DBK. Can I lengthen the sensor cable ? ( using the correct Thickness of cable of course)
It is very fine twin cable, but only 25 cm long and I want the controller at the bottom and fans, sensor etc at the top.
Ta.
Mitch.

 

[Lenny HB]

The sensor is a thermistor and lengthening the cable a metre or 2 won't make any odds.

 

[Diabalo]

I fixed my PCB at the top so the cable was long enough to position the sensor correctly, it has the added bonus in that I can see through the vent grills what's going on temperature wise on the LCD readout. I have no idea about gas saving as I have only been using it on lecky, I think my fridge is less efficient on gas and lecky is free when on hook up

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[MitchandJenny]

I just wanted the PCB out of the main heat, so will put it behind the lower grille.
Ta. both.
Mitch.

 

[Lenny HB]

Blimey you must be tall I can't even reach my top vent without a ladder
Normally fridges are more efficient on gas and cool much better also much cheaper to run on gas even if you haven't got refillable bottles.

 

[Lenny HB]

I just wanted the PCB out of the main heat, so will put it behind the lower grille.
Ta. both.
Mitch.

In the last van I fitted one of the PCB type ones in a plastic box behind the bottom vent with an on/off switch inside the van as once it is set up don't need to look at it. Current van I fitted one of the posher ones inside the wardrobe.
Temp setting will vary with fridge installation, last van I had it set to 35 deg current van 32 deg, I set the hysteresis on both to 2 deg. I found ideally you want it to turn the fans on when the outside temperature reaches 25 deg.

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[MitchandJenny]

No, definitely NOT tall mate, but I stand on the "hop-up" thingy.
Autotrail fridge TOP vent is only about 5ft 6inches off the ground.

HISTERFECKINRESIS ! ! ! ! ! ! WTF ! ! ! !
I had only just got things straight in my mind, and you start with the hysterickys things ! ! ! ! !
I've just got to find some cable of a similar thickness to extend my sensor probe, (thyristor) Ha ! ! ! !
put THAT in your pipe and smoke it.. Thyristor ! ! ! ! ! Heard THAT word on here somewhere ! ! !
I DO seem to remember theses terms from a 3 year vehicle tech apprenticeship back in the 60's at Carlisle Army training barracks. But seem to have managed without using them for 55 years.
Out with the soldering iron soon..
Thanks again for all the info. xx
Mitch.

 

[MitchandJenny]

That had you didn't it ! ! !
Thigh risker..
Mitch.