Reddit mentions of Inkbird ITC-100 PID Thermostat SSR Heat Sink Temperature Controller Relay Alarm Output 100-240V (ITC-100VH+SSR-40DA+K Sensor)

I've got extra adderall in my system that I need to burn off, so you're going to get the benefit of a decade of mechanical engineering and prototyping work in defense, consumer products, aerospace and medical. Not all of this will apply to a senior design project, but it is my thought process when prototyping.

1. Capture the voice of the customer (what EXACTLY does it have to do). Write it down. Verify it with the customer. Make sure you know exactly what success looks like. Translate this into the minimum viable prototype to achieve this success. Example of tradeoffs you can make at the prototyping stage: If it's a small portable device, but to go from phase 1 to phase 2 you don't have time to miniaturize the power supply, microcontroller, and secure batteries, the first prototype will be on a power and data tether from a laptop. If it's something mechanical that eventually has to weigh less than X, it can be fabricated quick and dirty as a proof of concept before you start adding expensive lightness.
   
   
2. Minimize innovation. Read that again. Minimize innovation. Don't be innovate anywhere you don't have to. Reuse whatever you can from the next closest thing, and only invent something new or do something unique/custom/cool/fun where you are adding unique value. Don't assume it is cheaper or easier or better to make something yourself instead of applying an industry-standard solution unless you already comprehensively know the pros and cons of the next best competitors and have a good idea why they made the tradeoffs that they did.
   
   
3. Try to only have one miracle per prototype. If you are inventing a new remote control something-or-other, don't try to test the controls and the mechanics and the motors and the battery all at once. Take an existing product and switch the motors out, put it back to stock and work the bugs out of the control system, then do the control system AND the motors, and once ALL of that works, try the control system, motors, and your new chassis all together, since you will be able to pinpoint what is going wrong much easier.
   
   
4. Know what questions you are trying to answer when you are going to consult with the customer. If you have a design decision, build prototypes far enough to be able to show them the difference (do you want it to work with a twist knob or a pull tab? How does this feel in your hand compared to this? Is this easy enough to adjust or does it need more friction?). Know before you talk to the customer what questions you want to ask.
   
   
5. Rapid prototyping can make beautiful parts...if you get good at sanding, bondo, and spray paint. It is worth a day of prep time to make your final version parts look nice. Anything that needs threaded fittings should get pressed and glued-in brass inserts, threads into plastic in prototype parts will strip exactly when you don't want them to and ruin your day.
   
   
6. For any actual fabrication, it will take twice as long and cost three times as much as you think it will right now. Always order a spare of anything with a lead time of more than 20% of your total project timeline if you can afford to, and if you can't afford to, think hard about if you should buy it anyway because when it breaks, not only will you be buying a new one, you will be expediting it. Don't be afraid to buy something that is 50% of what you want to make and throw away half of it, it's probably cheaper in the long run and the process of stripping down something similar to what you want to build might spark some ideas.
   
   
7. Get an account on McMasterCarr for anything physical like bolts, valves, fittings, bearings, etc. Get an account on Protocam for anything you need made of plastic--upload your parts to them, fill out a quick form, and they will give you quotes on whether they can make it, out of what material, and with which combination of machining or additive manufacturing (3d-printing). McMaster and Protocam can get you parts quicker than anybody else. Get a Misumi catalog. They are expensive but they are the industry standard for one-off fabrication of benches, tables, test rigs, etc for a reason--they are precise, modular, and durable.
   
   
8. If you want to add any electronics to your project, try to find something that is close enough and make it work--example, do not program your own temperature or flow control modules, just buy them. There are a whole lot of processes that can be controlled 'good enough' by a $30 PID controller off of Amazon. or clever use of limit switches and timer relays. If you can't do that, find someone who is good with Arduino and then google aggressively for similar projects (whatever it is, it has been done before) and steal as much of their code as you can get away with and still have it do what you want it to do. You will almost never need anything more than an Arduino unless you are a very CS-heavy group in which case you should know what you want to use instead.
   
   If you have specific or more focused questions around your project, I can reply to PM's if you'd like.

You'll need one or more Heating Elements inside your keg. The one I linked to is for water heaters. You need a 240V hookup, too. If you don't have one, these elements will work on 120V, but you're going to need more of them unless you want to wait an hour to get 5 gallons of water to boil.

You'll control these elements with a PID controller and one relay per heating element. The PID controller I linked comes with one good solid state relay that's capable of switching 240v. The PID controller also supplies you with the temp probe you need to put into the kettle somehow.

In addition to this, you'll need some various connectors, and probably an electrical box. I'd say budget a couple hundred bucks for odds and ends.

Finally, when messing with 240v... or even 120v, you really should get a real electrician to look over your connections before you apply power to it. A: to keep you safer, and B: to keep your investment safer.

If you want to keep them electric, making them computer controlled is FAR easier! You can use an SSR and a commercial PID controller to do the control without brewing your own electronics like I'm doing.

Something I'd like to try sometime would be to purchase an external PID temperature controller like this.

Or... just found this

... and remove the entire process from the printer control board.

I homebrew beer and in it seems more common for beer brewers to use a PID+SSR for controlling the heating element. Any reason for the PAC instead of PID?

PID + SSR + heating element:

http://www.homebrewtalk.com/showthread.php?t=160145

PID vs PAC:
http://www.homebrewtalk.com/showthread.php?t=410119

PID+SSR+thermowell on Amazon (US, but I'm sure you could find this or something similar on the UK site):

https://www.amazon.com/dp/B00ADHNSGI/