Fermentation chiller with RaspberryPi

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staticdev

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Hi all, I just bought my new brewing equipment with mash temperature control and got 2 chambers (with very simple static temperature STC1000). I also have one spare Raspberry Pi 2 B+ and I want to control these chambers with it.

I want to use CraftBeerPi. Besides the DS18B20 sensors and power supply, how do I know my freezers are less than 10A and I don't need SSRs? How to determine the model of SSR/relay? Any other important item?
 
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stlbeer

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There are a couple of different ways - look on the compressor and see if there is a rating indicating the startup and running amps requirement. You might also use a multi-meter or a Kill-A-Watt. Most regular refrigerators need about 15 amps to start then back down to a couple of amps for running. For this reason the little 10amp relays are not recommended. You will shorten their life spans and eventually they will burn out or stick on. Instead, search for a 25 amp SSR (not a branded Fotek).
 

jordo_99

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Instead, search for a 25 amp SSR (not a branded Fotek).
Any particular reason to avoid the Fotek brand? I recently started looking at solid state relays with high amp ratings and I've been seeing that brand everywhere.
 

cegan09

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SSRs burn out primarily because people don't cool them sufficiently. There is a percentage of them that are just garbage, but if you fail to keep them cool they will die faster.

FWIW, you do not NEED an SSR for a fridge. You are not switching it on and off rapidly, so a regular relay is just fine. I've had one of those 10A relay boards on a fridge that's been running non-stop for over 2 years now. No problems whatsoever. I did check the rating of the fridge and it doesn't state anything over 10A. Of course going to a unit with a rating higher than your load will certainly not hurt anything.
 
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