diy: temperature controller


i feel like we lead a pretty simple life, until i spend an entire morning building a highly specialized tool for a niche job like rising sourdough bread and infusing herbal oils. today my mom and i built a temperature controller which will be used to turn a camping cooler into a chamber for rising bread, infusing oil, making yogurt, and anything else that requires temps in the range of 80-110 degrees.

we do live ‘simple’ in the sense that we buy very few material possessions, cook all our meals at home, and love DIY entertainment. living without the TV always on or places to drive around to for shopping leaves you with a lot of free time. we fill that time with our hobbies – andrew plays a few different types of stringed instruments, homebrews, grows and studies mushrooms, is an avid board-gamer, and loves to cook. i practice herbalism and yoga, garden, sew, homebrew, hike, bake sourdough bread, and love all manner of diy projects (just to name a few!). this is the main draw for us to lead a less consumer driven lifestyle that’s not focused around making money – we derive joy from having time for all our hobbies (and from constantly finding new ones!).

maybe it’s the type of hobbies we have or our personalities, but it seems like once we start to get really into something it’s not long before we need special equipment or some elaborate set-up to take our hobby to the next level. being us, we usually mull over anything we have to purchase to decide if it’s worth it or not. which of course leads me to do some research and figure out if there’s a way for me to make all or part of it from scratch to both save money and end up with a higher quality piece of equipment.

in the case of the temperature controller, i was able to do part of the labor myself sourcing the core element from the internet and everything else from the hardware store. my mom helped greatly and we did all the work in her shop using what feels like way too many varieties of saws. anyways, i ended up with a tool that functions better than what you can buy from a homebrew supplier at half the cost.

if you are into fermenting anything, making yogurt or cheese, infusing oils, baking bread … you probably already know that controlling the ambient temperature around your project is important. we accomplish this with a digital temperature controller because it allows you to monitor temps right down to the degree. the temperature controller acts as a thermostat that tells your heating/ cooling appliance when to run to maintain the desired temperature.


here’s how it works – you buy a basic controller off the internet like this. this unit includes a temperature probe which is eventually run to your chamber where you brew or whatever is contained. you then attach a basic wall outlet to the controller, ‘breaking’ the outlet so that one side controls your heating element and one side controls your cooling element. you run a power cord to the controller, set it all up neatly in a project box, mount the box to the wall, plug in your heating and cooling appliances, and boom. it makes more sense with photos. also, use this guide if you plan to try this project, i found it to be very clear.


first we cut out holes in our project box where the controller, outlet, and power cord would fit. we did this with a professional combination of two dremels, a hacksaw, drill bits, and files. this was easily most of the time we spent on the project!!


then we fit the controller and outlet onto the box…


harvested some wires from our 8′ power cord ..


did all the wiring according to the diagram from the guide …


put everything together, and that was it!


like i said, the hardest and most time consuming part was cutting out all the holes. total we spent about 3 hours on the build and $30.

this is our second one of these units – our friend’s dad was kind enough to build us our first one last spring. controller one is hooked up to a chest freezer that is where we ferment all our homebrew. i watched him make it, and decided to try the second with my mom. controller two will be hooked up to a seedling germination pad that will lay in the bottom of an insulated camping cooler and will be for all our warm needs.

the best part about embracing the DIY lifestyle is not ending up with higher quality goods or saving money …  it’s that in the process of learning to do something yourself instead of buying it or outsourcing it, you pick up valuable skills. after this project, i feel comfortable with small scale electrical work – something that used to terrify me! i know how to read a wiring diagram, i learned to connect wires, etc. this skill will come in handy when we renovate or build a house.

diversifying your skill set is important to becoming more self-reliant, which is an critical piece of my financial independence plan. plus i love the independence, freedom, and empowerment i gain through doing things myself!

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