Wiring Temp Control into Fridge

[wildburkey]

Sorry to double up on posts here I am terrible at keeping on topic in forum's.
It seems most people here use project boxes to build temp controllers for their keg fridge or fermentation fridges, I just thought I'd share how I went about installing my single relay digital temp controller in a fridge with a buggered thermostat that I picked up for free.
The advantage in doing it this way is that you purchase less to achieve the same. The disadvantages - it would void warranty, the controller can not be used for anything other than controlling the temp of the fridge/ freezer it is installed in, and it will take a bit more understanding of your fridge/ freezer circuitry.
So here is what I have done, it's quite simple really if you have a fridge with a 240v light inside.
Running into the fridge there are a live (brown), neutral (blue), earth (green and yellow), and in my case a white wire which gets connected by the thermostat to the live (brown wire) to kick the compressor starter on and off.

In the picture above I have gutted the old thermostat and light and just kept the wires (with the white and brown twisted together the fridge compressor constantly runs)
From here I wired the active and neutral to power the controller, jumped the active from the input on the controller to one of the inbuilt relay switch terminals in the controller, and connected the white in the other relay terminal.

Once tested I cut a hole in the door, extended the wires and installed the controller in the door.

Here is a pic of the completed project -


I should note I am not a qualified electrician, I do have a good understanding of refrigeration mechanics. I am going to get a sparky to check this before consistent use and will keep ya'll updated when fully tried and tested. Circuitry may differ between fridges and a qualified sparky should be consulted if undergoing this project.

In theory the method I have used could also be used in conjunction with the existing thermostat cranked up on high if you connected the digital control relay in front of it and the light could be kept if power is taken in front of the switch!

Cheers all, I hope this can help someone.

 

[wildburkey]

I got the A OK on this from a qualified sparky :beerbang:
Gunna test it out with a fermenter full of water and log high and low temps with a separate thermometer.
I should also note - the fridge is earthed from the compressor, the lonely earth wire was for the fridges original thermostat (the digital controllers I have come across do not need grounding); it is essential to have the fridge grounded! This will come in handy when I convert to a dual relay STC-1000 if I should add a heater that requires earthing.

 

[glenwal]

I'd be putting a nylon screw or something in the door/flap that the controller is behind.

Don't want a drunk mate getting curious and opening it up.

 

[wildburkey]

Yeah I was saying that I should do that to a mate I was showing, he'd prob be the culprit if I don't now, going to wait till I get the STC to control both hot and cold and do just that thanks Glen.

 

[Ducatiboy stu]

Groan

 

[S.E]

I would be uncomfortable having live wires inside a fermenting fridge, they can get quite damp inside. Mine often has condensation running down the door and sides.

 

[Camo6]

Is the fridge door grounded?

 

[wildburkey]

I'll keep an eye on moisture, I'm going to lock, seal and screw the compartment shelf in once the STC arrives, I'll put some silicon around the joined wires also. There is nothing conductive near the live wires in the door but might as well ground it to be sure. Cheers

 

[S.E]

I'll keep an eye on moisture, I'm going to lock, seal and screw the compartment shelf in once the STC arrives, I'll put some silicon around the joined wires also. There is nothing conductive near the live wires in the door but might as well ground it to be sure. Cheers

I usually open ferment or put the lid on loosely so can get a fair bit of condensation in winter. If you seal the fv with an airlock or glad wrap it may not be a problem for you.

 

[Camo6]

I'll keep an eye on moisture, I'm going to lock, seal and screw the compartment shelf in once the STC arrives, I'll put some silicon around the joined wires also. There is nothing conductive near the live wires in the door but might as well ground it to be sure. Cheers

Moisture is conductive. Just thinking if that exposed foam took on condensation which found it's way into the vented STC housing, that whole door could become a conductor with no path to ground (except maybe through you if you're lucky).

When it comes to electricity, there's a rule book as thick as the Bible primarily implemented to prevent death or injury by electric shock. Earthing requirements has it's own chapter. Sounds like your sparky may have skipped this section or just has a penchant for free beer. :unsure:

 

[Ducatiboy stu]

Dont **** with 240v electricity. Its a pretty simple moto to follow

 

[kunfaced]

Moisture is conductive. Just thinking if that exposed foam took on condensation which found it's way into the vented STC housing, that whole door could become a conductor with no path to ground (except maybe through you if you're lucky).

When it comes to electricity, there's a rule book as thick as the Bible primarily implemented to prevent death or injury by electric shock. Earthing requirements has it's own chapter. Sounds like your sparky may have skipped this section or just has a penchant for free beer. :unsure:

This is completely correct. I am a sparky and i can tell you your set up needs to meet the demand of an rating of IP54. This covers particles in the fridge and condensation/splashing. If you care about making it proper, that temp controller needs to be in it's own segregated enclosure, and the cables coming back into the fridge (double insulated) through grommets, all sealed with silicon at the least.
I would cover that hole you carved with some sort of metal plating, then over the top of it mount a plastic box of some sort. It could be metal as long as it is earthed sufficiently. you can leave your cables as long as you need inside the separate enclosure, so you can pull it out and look at the back of the controller as needed. Sorry for being a douche.

If you want to check out for yourself the minimum requirements, IP ratings are on wiki:

https://en.wikipedia.org/wiki/IP_Code

It is an international standard, and for good reason. Imagine the entire inside of your fridge being live because of condensation. This is your potential at the moment.

 

[S.E]

To be fair he has had a qualified sparky check it over. And it sounds like he on to the safety side of things and aware of the problems ingress of moisture could cause.

He has connected his STC to the existing vented 220v light supply inside the fridge and intends to seal it all up so should be safer than it was before.

I bet most people would be happy using an external STC and just leaving the existing exposed 220v light unsealed.

 

[Camo6]

To be fair he has had a qualified sparky check it over. And it sounds like he on to the safety side of things and aware of the problems ingress of moisture could cause.

He has connected his STC to the existing vented 220v light supply inside the fridge and intends to seal it all up so should be safer than it was before.

I bet most people would be happy using an external STC and just leaving the existing exposed 220v light unsealed.

The difference being the original light/thermostat was mounted in a plastic panel and earthed directly. Not mounted in a painted metal door that previously held no electric components and probably not adequately grounded to the rest of the fridge.

I use external STC's but they're double insulated, have no external conductive parts and use an intact earth circuit.

I applaud the OP's resourcefulness, and reckon it will make a great ferment chamber once he makes it safe but let's not create an online DIY guide for a potential death trap without exposing the risks.

 

[S.E]

The difference being the original light/thermostat was mounted in a plastic panel and earthed directly. Not mounted in a painted metal door that previously held no electric components and probably not adequately grounded to the rest of the fridge.

I use external STC's but they're double insulated, have no external conductive parts and use an intact earth circuit.

I applaud the OP's resourcefulness, and reckon it will make a great ferment chamber once he makes it safe but let's not create an online DIY guide for a potential death trap without exposing the risks.

I understand your concern that the door should be earthed and the OP took that point on board and said he would do it as an extra precaution even though he pointed out that the wiring was double insulated by the plastic internal door and the double insulated STC.

Even though the original light fitting is mounted in plastic and earthed there are still 220v exposed/unsealed wires there, so that and those in the newly mounted STC is what I would be uncomfortable about in my damp fermenting fridge.

I don’t think the op is trying to create an online guide for a potential death trap, but putting forward his idea and open to and taking on board input and suggestion.

 

[Ducatiboy stu]

I applaud the OP's resourcefulness, and reckon it will make a great ferment chamber once he makes it safe but let's not create an online DIY guide for a potential death trap without exposing the risks.

This is why I cringe whenever I see a thread on here that has anything to do with mains power.

Personally I would like to see the mods & admin stop the posting of things to do with electrical wiring.

Imagine if someone got killed or injured and during the investigation the builder said " Yeah..I saw it on a thread on the internet .."

Sorry...BUT DONT **** WITH ELECTRICITY

 

[Ducatiboy stu]

To be fair he has had a qualified sparky check it over. And it sounds like he on to the safety side of things and aware of the problems ingress of moisture could cause.

He has connected his STC to the existing vented 220v light supply inside the fridge and intends to seal it all up so should be safer than it was before.

I bet most people would be happy using an external STC and just leaving the existing exposed 220v light unsealed.

I have seen plenty of sparkies get it wrong....and its the simple basics that they get wrong most of the time

 

[S.E]

This is why I cringe whenever I see a thread on here that has anything to do with mains power.

Personally I would like to see the mods & admin stop the posting of things to do with electrical wiring.

Imagine if someone got killed or injured and during the investigation the builder said " Yeah..I saw it on a thread on the internet .."

Sorry...BUT DONT **** WITH ELECTRICITY

Don’t think anyone is suggesting people unfamiliar with electrical wiring should **** with it Stu. Just sharing knowledge on brewing gear.

Would you like the mods & admin to stop the posting of brewing alcohol? After all there is so much depression, violence, injury and death caused by it?

 

[S.E]

I have seen plenty of sparkies get it wrong....and its the simple basics that they get wrong most of the time

I have also seen and employed a few qualified sparkies that got it wrong and had to put it right myself. I am not a sparky.

 

[kunfaced]

I have also seen and employed a few qualified sparkies that got it wrong and had to put it right myself. I am not a sparky.

I am a sparky and I do nothing but fix other peoples crap. Bad things have pointed out and it should be done right. It's an appliance though so OP can do what they want. At least if you're a Catholic drinker, you wont be proof of Darwinism.

PS the qualified sparky who checked it out should be checked via resit of A grade exams.