Fridge hacking guide

[The-Engineer-That-Brews]

This blog/howto is a bit more detailed than most and has good photos and a few useful tips:

Fridge hacking guide: converting a fridge for fermenting beer | BrewPi

Random points I picked up:

• if you run a cable/gas line in through the drain hole, ensure that condensation doesn't run down it and drip onto the electrical gubbins
• fitting a fan inside the fridge will help maintain an even temperature distribution (but the beer probably doesn't care much)
• there will be a start-up relay somewhere that feeds extra current to the compressor for the first half-second or so after the thermostat triggers
• therefore it is a BAD idea to keep turning the compressor on and off more often than necessary
• if you want to use an additional sensor to measure the temperature of the beer then put it in a thermowell or similar - taping the sensor to the outside of the FV doesn't work well even if you insulate it. Edit: do not use a thermowell as the location for the feedback sensor for the fridge controller because you will get massive temperature swings.
• don't use cheap SSRs off eBay or Amazon (especially ones branded Fotek) as they will be fakes. Spend a few quid more and get a decent one from RS or DigiKey etc

Side note:
If you're controlling a fridge with any kind of electronic switch (SSR or mechanical relay) then it's important to understand that it's a highly inductive load. This means that it is much more difficult for the switch to control it, so double check the rating of your switch to make sure it's up to the job. For example, a "10 Amp" relay is normally only rated at 7.5A for inductive loads.

 

[stripeyjoe]

I do find I get less temp swings in my fermentation fridge if I mount the sensor on the side of the FV rather than stick it in the thermowell, when it's in there by the time the centre of the 23l has warmed up the rest of the fridge is way too hot, I then get a temperature spike and the fridge turns on and then the reverse happens on the chill cycle. I think having the sensor mounted on the side of the FV gives more of an 'average' temp of the fridge, which the entire contents of the FV will eventually reach.

 

[The-Engineer-That-Brews]

I do find I get less temp swings in my fermentation fridge if I mount the sensor on the side of the FV rather than stick it in the thermowell, when it's in there by the time the centre of the 23l has warmed up the rest of the fridge is way too hot, I then get a temperature spike and the fridge turns on and then the reverse happens on the chill cycle. I think having the sensor mounted on the side of the FV gives more of an 'average' temp of the fridge, which the entire contents of the FV will eventually reach.

Oh yes! I couldn’t agree more: you definitely shouldn‘t put the feedback sensor in a thermowell because you’d get massive swings in the fridge temperature.
I should have clarified that I was talking about an auxiliary sensor for measuring the temperature of the beer itself :-)

 

[The-Engineer-That-Brews]

Note: I'm currently doing my own kegerator build based on the same sort of approach: TETB kegerator build