HestiaPi: A Stylish Open Hardware Thermostat

A common complaint about open hardware and software is that the aesthetic aspects of the projects often leave something to be desired. This isn’t wholly surprising, as the type of hackers who are building these things tend to be more concerned with how well they work than what they look like. But there’s certainly nothing wrong with putting a little polish on a well designed system, especially if you want “normal” people to get excited about it.

For a perfect example, look no further than the HestiaPi Touch. This entry into the 2019 Hackaday Prize promises to deliver all the home automation advantages of something like Google’s Nest “smart” thermostat without running the risk of your data being sold to the highest bidder. But even if we take our tinfoil hat out of the equation, it’s a very slick piece of hardware from a functional and visual standpoint.

As you probably guessed from the name, the thermostat is powered by the Raspberry Pi Zero, which is connected to a custom PCB that includes a couple of relays and a connector for a BME280 environmental sensor. The clever design of the 3D printed case means that the 3.5 inch touch screen LCD on the front can connect directly to the Pi’s GPIO header when everything is buttoned up.

Of course, the hardware is only half the equation. To get the HestiaPi Touch talking to all the other smart gadgets in your life, it leverages the wildly popular OpenHAB platform. As demonstrated in the video after the break, this allows you to use the HestiaPi and its mobile companion application to not only control your home’s heating and air conditioning systems, but pretty much anything else you can think of.

The HestiaPi Touch has already blown past its funding goal on Crowd Supply, and the team is hard at work refining the hardware and software elements of the product; including looking at ways to utilize the unique honeycomb shape of the 3D printed enclosure to link it to other add-on modules.

20 thoughts on “HestiaPi: A Stylish Open Hardware Thermostat

  1. Damn, that looks a lot neater than my version which uses a 1.5″ OLED, physical buttons, and a Pi Zero to control a sonoff connected to the boiler via Home Assistant :( Time to fire up Fusion 360 again :)

    1. Mind the air flow and leave plenty of empty space inside the case. Our initial designs were as big as the internal parts. Sensor was reading ~10 degrees higher unless you move to active cooling which is a no-no for 24-7-365 operation

  2. Very nice project. A few ideas:

    Could save some board space, Relays are oversized, residential equipment should/will draw less than 1amp through the thermostat.

    Could also add an indicator light inside of the enclosure, red for heating, blue or green for cooling (venstar thermostats have this on the front, easy to see if heat/cool is active from across the room), let it shine out from inside the enclosure. Then can auto off the display if wanted.

    It would be nice to see a safety lockout so that cool relay cannot energize when heat is on, maybe dpst relay feeding the other? Eg NC on heat relay feeds to C on Cool relay.

    You are going to control the reversing valve for heat pump systems with the heat relay? 90% energize O terminal when cooling, 10% (Rheem and ruud) are opposite – energize B terminal for heat. If you are going into extremely cold climates you might need an emergency heat relay/switch too…

    1. Thank you for your constructive ideas!
      We try and use easy to source parts, including solid state relays (SSR). Surely less overengineered components could be chosen…
      Your LED indicators idea is cool maybe in one of the next iterations we will add something like this (and people will ask to turn them off ;) )
      The SSR don’t have a dpst but your logic makes sense. So far openHAB has been great with absolutely no mistakes/freezes like this but of course we cannot ignore this.
      We have an additional relay for 2-stage furnace which can easily be used for emergency heat instead. Do you have a wiring diagram for your example?

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