Future Build w/ Love Controllers - Questions

I would like to build my own brewing rig in the future and would like to have the temperature control for my keggles. I will be using propane gas. I was looking at the love controls. Reading the forums on here I don't understand how Relays, pid, ect.. works. Could someone enlighten me or point me in the right direction? Thanks in advance

The Love control has an interface that closes a circuit and opens one when it has either reached a set point determined by the user or is below or above the acceptable range that the user has set.

In other words, you set the Love controller to 152* your temp probe in your mash tun will tell the real temp of the mash... when the mash goes below lets sat 151* this will send a signal to the Controller to turn on the device it is controlling... In this case it would turn on an ASCO valve that opens a propane valve to fire up the propane burner until that temperature has been reached... Then it shuts the valve.

I hope that helps you.

Here is a link to a diagram and parts list for the typical Brutus design brew system That Lonnie Mac has pioneered.
https://www.homebrewtalk.com/f11/low-pressure-ignition-system-wiring-diagram-153752/. If you have other questions or need some help in finding the components PM me and I will help as much as I can.

Relays take a low input voltage and open/close a set of contacts connected to a higher output voltage.
PID is basically a programmable Relay with temp control as an input.

Simple Love TS switches are basically thermostats that turn on heat if below set point and turn off heat when above.

PID or Proportional Integral Derivative controllers are much smarter. They can 'learn' the rate of change and thermal properties (in the case of heating) of what they control. They can proportionally control the heat, but most of us don't use that feature. They can also predict the overshoot of temperature based on historical data and turn off the heat before the set temperature is reached and allow it to coast up to that point.

An example of a PID controller is my Honeywell thermostat at home. If I want it to be 70 degrees at 6AM it knows how long it takes to heat it from the current temperature and if the set point is far away it will kick in the second of my two stage furnace in to bring the temp up faster. If it's 50 it might fire up at 4:30AM. It examines the last 3 days to help predict it. I want it to be 70 at 6AM, not turn the furnace on at 6AM like a TS would do.

This is an example of a PID controller with an "auto tune" or learn feature that we would use in brewing.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200402591755

On topic hijack: Do the PID's tune themselves each brew session, or do they use historical data from past brews? If they use past brews, does the controller require a constant source of power to retain such information?

That would be PID dependent I suppose. The auto-tune function actually applies a small amount of heat and watches the temp swing, on the device I linked. The parameters are in non-volatile memory. The previous days are something my PID does for the furnace control as an example and as far as I know, doesn't apply to these controllers.