eBIAB PID help

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olimrrs

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Well lets first start with my system. I have recently moved from stove top brewing to a 21l (or +5 gal) pot with a 2000w element on 220v (South Africa). It boils well but is a mission to keep it on temp, now I am thinking about having more control over my brews.

This is where the help is needed. For about a week I have been reading up on other members control panel builds with diagrams but cant comprehend for the life of me on how all the pieces (pid and ssr) connect to the element.
Can I just buy any pid, ssr, temp probe and heatsinks and wire them all together? For example could this package work if I also bought a heatsink http://www.ebay.com/itm/100-240V-Di...477?pt=LH_DefaultDomain_0&hash=item258707f87d until such a time I upgrade to a mash tun and hlt and bigger bk?

If you got this far thanks for taking the time to read about my stupidity as electricity and I don't mix.
 
The main issue is that all the components match your load & service voltage. 2000W/220V=9Amps I'd suggest a minimum of 20A SSR. Bigger is better in this case.
Likewise on the PID, it just needs to be rated for 220V and have a SSR output. Some PID's only have a relay closure. The thermocouple needs to rated for the heat range you'll be working at, 0-100C You can look up thermocouples in a chart, and it will give you the temp range accordingly. A K-thermocouple is good from -200 to 1350C, well within the range of boiling water. PID controllers allow you to select the thermocouple type in the configuration menu.

The SSR is just a switch. You wire it in series with one leg of the AC going to your heating element. Hot into one terminal of the SSR, The other terminal to the heating element terminal. The Small terminals on the SSR go to the PID, you just observe the correct polarity when connecting the PID + to +, - to -

All that said, the eBay auction package will work for you. But with a caveat, I would check to see if the PID controller has a manual mode. What the manual mode allows you to do is control the duty cycle or "on-off-on-off cycle" manually. It's usually based upon the ON Time percentage. The reason I suggest manual mode is it's been my experience that typically PID controllers are not well suited to controlling large slow moving thermal masses.

The problem being you have a large mass to heat within a finite window of time, a PID controller generally works best in lower thermal mass situations like heating air. Or in the case of liquid, in a RIMS tube setup where the liquid is flowing over the heating element and the temperature can be sensed immediately down stream. In heating a large mass, like a kettle, the smart PID controller tends to overshoot the target temperature by quite a bit then it takes a long time to cool back down which in turn causes the PID controller to undershoot the target temp. During this time the PID is trying to 'learn' the heat loss & gain in the system, which it will do, eventually, but it may take several hours. Obviously you don't want your mash or boil temps swinging wildly over a period of 60 or 90 minutes.
This is where manual mode comes in. You can do the work of the PID but in a much shorter period of time. Basically, you run the kettle up to mash temp as fast as possible, then use manual mode to dial in the percentage of time or duty cycle (on-off) to hold that temp. In my kettle system, 55% duty cycle in manual mode is what works for me. I can go a few percent more to get 1-2 DegF rise or drop in temp. Likewise on the boil, you can go full on at 100% to reach a boil then back down to maintain maintain the boil without boiling over. Like you would normally do with a kitchen stove.
All that being said, Member 'Matho' designed the Brauduino system which uses an Arduino board and it's programmed with a PID control, to avoid the typical undershoot/overshoot problem, he programmed the control not to switch to PID control until it was within 95% of the target temperature. You can do the same by using an override switch to heat the kettle to within 10 degF of your mashing temp before turning it over to PID control.
You could skip the PID control altogether and use a PWM control to drive the SSR. You have to have a PWM control that has a slow ~1Hz output as opposed to those typically use for lighting. The PWM & SSR along with a digital thermometer and a little patience will give you the same result. And again, I'll point out that this is in the case of large thermal masses like a kettle with a heating element in the bottom and likewise this is from my personal experience.
 
Please note that people have had many issues with the Rex PIDS and they only have an output for Relay even though there sold with an SSR. Your better off getting a package like This and picking up a K type thermocouple from Amazon for cheap. Good luck.
 
PID automation is nice but you can also control temp manually (element on/off and thermometer) and insulate the kettle or use a cooler to maintain mash temp for 60 minutes.

If you want to automate the myPin TA4/TD4 PIDs are pretty cheap and work well for many brewers.

Your heating time and max boil capacity will be limited by the 2000W element. If you have a 30amp @220v power source you can use a 4500W or 5500w element.
 
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