Bypassing fridge thermostat

The forum for discussing all kinds of brewing paraphernalia.
Post Reply
simpleton
Piss Artist
Posts: 107
Joined: Wed Jul 10, 2013 10:14 am

Bypassing fridge thermostat

Post by simpleton » Thu Jan 25, 2018 2:05 pm

Took it apart and I'm now staring at it. But there are more wires than I was expecting. As usual!

Fairly sure I join the brown and black wire but thought I'd check before I go ahead!

Dunno if this picture is gonna work from Google drive but here goes...

https://drive.google.com/open?id=19v-lZ ... 5kXfhacwxN

Join Brown and black right?

If its not clear from pic...
Grey goes just to light.
Purple goes from thermostat to light.

Cheers
Si

User avatar
Wonkydonkey
Drunk as a Skunk
Posts: 847
Joined: Sat Mar 01, 2014 9:37 am
Location: In the Stables

Re: Bypassing fridge thermostat

Post by Wonkydonkey » Fri Jan 26, 2018 1:39 pm

I,d say yes,

But if you have a look around on here and the interwebby there are a few different ways to do it, depending on what sort of outcome you want and what fridge or freezer you got

I was reading about just bypassing the fridge thermostat altogether, and going straight to the compresser. If your rigging up an STC100 it could be a better option.

But if your sure you want to hack the thermo, you could check your wires with a multimeter, by seeing if you have a voltage on each side when the fridge is on, or check for continuity.
But remember electricery hurts if you get it going through you. :shock: :shock: .....be carful like... :wink:

Edit add linky:
viewtopic.php?f=6&t=70226
To Busy To Add,

aamcle
Drunk as a Skunk
Posts: 767
Joined: Tue Jan 15, 2013 11:42 am
Location: Newton-le-Willows ( St Helens/Warrington)

Re: Bypassing fridge thermostat

Post by aamcle » Fri Jan 26, 2018 5:21 pm

Why would you want to?

Turn the fridge up to max and a STC or Inkbird will control the heater (if you have one) and the fridge independently.

There is no need to modify the thermostat.


aamcle

chris2012
Under the Table
Posts: 1111
Joined: Sat Jun 23, 2012 10:13 pm

Re: Bypassing fridge thermostat

Post by chris2012 » Fri Jan 26, 2018 6:02 pm

I'm just wondering, could you possibly get the fridge colder by bypassing the thermostat though, I'm not sure if that's the case or not though?

I hacked the thermostat for my fridge and use an inkbird, but I can't remember exactly if I experimented much with the thermostat in place.

User avatar
alexlark
Under the Table
Posts: 1354
Joined: Thu May 02, 2013 12:29 pm
Location: Rhondda, South Wales

Re: Bypassing fridge thermostat

Post by alexlark » Fri Jan 26, 2018 6:27 pm

Had to remove my thermostat last week. It was picking up ambient and wouldn't crash cool below 4c.

simpleton
Piss Artist
Posts: 107
Joined: Wed Jul 10, 2013 10:14 am

Re: Bypassing fridge thermostat

Post by simpleton » Fri Jan 26, 2018 6:44 pm

I want to do it as even on my max the compressor gets turned off by the thermostat. I can only get beer down to 3 or 4C.

So I've bypassed the thermostat and am switching the compressor with a relay I've wired at the back that is wired to a brewpi setup. Not tried yet but suspect it will get it down to 0.5c when I need. Probably freeze the beer given half the chance.

User avatar
alexlark
Under the Table
Posts: 1354
Joined: Thu May 02, 2013 12:29 pm
Location: Rhondda, South Wales

Re: Bypassing fridge thermostat

Post by alexlark » Fri Jan 26, 2018 8:39 pm

Mine is BrewPi controlled too. With thermostat removed no problem what so ever getting down to 0c.

User avatar
Wonkydonkey
Drunk as a Skunk
Posts: 847
Joined: Sat Mar 01, 2014 9:37 am
Location: In the Stables

Re: Bypassing fridge thermostat

Post by Wonkydonkey » Fri Jan 26, 2018 9:59 pm

I thought maybe largering, or crash cooling, or fecked/incorrect thermo.That's why I posted the link,


Cheers
It's Friday and it's been beertime
:wink: :wink:
To Busy To Add,

lord groan
Lost in an Alcoholic Haze
Posts: 507
Joined: Sun Aug 12, 2012 12:34 pm
Location: Hampshire

Re: Bypassing fridge thermostat

Post by lord groan » Wed Jan 31, 2018 10:03 pm

I did as WonkyDonkey suggests - I fitted an STC 1000 to my fermenting/chiller fridge, I bought 2m of 4 core flex and an STC1000

This is what I did on my fridge...
I UNPLUGGED THE FRIDGE!!!

Then I took the stat off the side of the fridge and fed the STC temp. sensor wire through from the back into the fridge
Then I identified the live (from the stat) and neutral connections to the compressor.
I disconnected the live feed to the compressor, coming from the stat, and disconnected the other end from the stat inside the fridge and removed that wire.

I fitted a small heater inside the fridge and fed the wire for it out through the condensation drain hole at the bottom of the fridge.

I connected 2 of the cores from the 4 core flex to the live and neutral terminals coming from the LNE terminals from the fridges 13A plug, then the other ends connected to the live and neutral connections on the STC.
I jumpered the live feed to the STC on pin 1 across to pins 5 and 7 which will supply the power to either the heater or compressor via pins 6 and 8

Live in to pin 5 comes out of pin 6 when the STC wants to switch on the heater
Live in to pin 7 comes out of pin 8 when the STC wants to switch on the cooling/compressor

Then I used the other 2 cores in the flex to run the switched feed from pins 6&8 back down the back of the fridge. From the cooling terminal I attached the wire to the live connection on the compressor
From the heater wire a choccy block connected that to the live heater wire coming out from the drain hole.

The neutral from the heater got connected to the neutral on the compressor/'neutral in' from the plug

Then the 2 connections from the temp sensor went to the STC pins 3 and 4

All done!
Power up the STC and set your desired temp!

I've made my larder fridge run at -2c just to see if it would work as a freezer,
I've used it to cool the fermenter after fermenting finishes and before I bottle
and I'm currently fermenting at 20c
At Christmas brewing stops and the fridge gets set to 4c and is used as an overflow fridge for all the extra christmas goodies
The STC is a brilliant little device. Notice I left the live feed to the stat connected - simply because that powers the fridge light.

I cannot guarantee that the pins on the STC won't have changed since I bought mine so if you do go down this route pay attention to the diagram on the STC not to my pin numbers above
Warning
I am not responsible if you do this - it's how I did mine but I'm not taking the blame if you get it wrong!

Hope this helps
LG

User avatar
alexlark
Under the Table
Posts: 1354
Joined: Thu May 02, 2013 12:29 pm
Location: Rhondda, South Wales

Re: Bypassing fridge thermostat

Post by alexlark » Wed Jan 31, 2018 10:20 pm

Just reading that sounds like you got no earth for the fridge?

Actually, you still got the original fridge cable connected, right?

lord groan
Lost in an Alcoholic Haze
Posts: 507
Joined: Sun Aug 12, 2012 12:34 pm
Location: Hampshire

Re: Bypassing fridge thermostat

Post by lord groan » Wed Jan 31, 2018 11:28 pm

Yup, I never had to touch the earth - definitely still connected. The Live, neutral and earth come in to a terminal block from the mains plug, that hasn't changed. The earth is still connected to the metalwork- thats unchanged too. But from the terminal block the live goes to the STC and from there is switched to the compressor and heater as required
Neutral virtually untouched too - just added the STC and heater neutrals to the existing neutral terminal (compressor obviously already had a neutral connection in place)
Cheers

User avatar
alexlark
Under the Table
Posts: 1354
Joined: Thu May 02, 2013 12:29 pm
Location: Rhondda, South Wales

Re: Bypassing fridge thermostat

Post by alexlark » Thu Feb 01, 2018 10:16 am

Sounds like a neat solution. I ran with an STC for a few weeks, then built a BrewPi. I still use an STC for the beer keg fridge.

If you want more control and like tinkering check out fermentrack.com that's the build I'm running with now.

User avatar
Wonkydonkey
Drunk as a Skunk
Posts: 847
Joined: Sat Mar 01, 2014 9:37 am
Location: In the Stables

Re: Bypassing fridge thermostat

Post by Wonkydonkey » Thu Feb 01, 2018 6:55 pm

I tried to follow your post, it made my brain go, pop pop ping. Then I got to the bottom, I,m pleased it worked out for you.
It's always good to get lots of ways to do something, then you get to choose the way that you thinks best..for your needs

Cheers.
To Busy To Add,

lord groan
Lost in an Alcoholic Haze
Posts: 507
Joined: Sun Aug 12, 2012 12:34 pm
Location: Hampshire

Re: Bypassing fridge thermostat

Post by lord groan » Sat Feb 03, 2018 2:58 pm

I'll admit I started with considerable trepidation Wonky, but taking it one step at a time and not thinking about the whole job meant it went quite easily in the end.
It seems complicated but it really isn't
cheers

Post Reply