Design a controler for an apratment storage heater

  • Status: Closed
  • Prize: $50
  • Entries Received: 5
  • Winner: anatol33

Contest Brief

Summary: design an electro-mechanical controller for a residential storage heater via the two control knobs on top.

I live in an apartment with 5 of these heaters (you can research them online here) [login to view URL]
per the article they have two controls, shown in the attached photos. I want a way to control these heaters from my computer/iphone so I control the charge/discharge remotely and/or automatically. The circuit that powers these heaters is only on from 10pm to 12 noon, then shuts off…If I have forgotten to charge the heaters and its cool, then I'm out of luck until 10pm…brrrr. Maybe the app can look up the weather report for tomorrow and think ahead. That is it any solution is fair game. Here are some constraints, the comments in [] are my ideas you can ignore or use these as you see fit, they are provided more to give you a sense of what I THINK the challenges are you may have better ideas of what the real problems will be.

• I cannot modify the devices, or harm them in any way, this is a rental. So for example I cannot just tap into the power supply and insert a relay, they are hard wired, I cannot drill into the case or remove the handles of the knobs
o [maybe magnets could hold a frame onto the steel case, and or the case could wrap around the edges of the unit to push against the torque of turning the vent dial]
o [The knobs have lots of surface area to grip, but the grip has to be non destructive, maybe 4 pins or a molded epoxy putty with a key shaft, formed around the knob protected with saran wrap?]
• The left knob, controls a flap that controls air flow through the brick core, it is very hard to turn, maybe a kg of force on each finger, hard to do with two pinky fingers, firm but moderate with a thumb and forefinger, the right knob, the thermostat is very smooth and easy to turn
o [a stronger servo/stepper motor may be needed for the left one]
• The knobs turn about 320 deg, but I think I could get buy with 180 deg, OK, more would be better but 180 would work. The first 90 deg, starting at the * does not seem to do much.
o [most servos only go 180]
• The face plate says the unit consumes 800W and can store over 10kwH, maybe it would be cool to have a room temp and unit temp sensor, but maybe not needed?
o Top of the unit (where the knobs are) gets quite hot but you can just barely hold your hand on it, so mechanism should be ok, and a therm couple there could estimate internal temp, if that is useful.

My goal is to build (all or mostly by myself) several of these units, so I'm looking for a design which:

• Is easy to make with only basic tools that balances total cost with ease. For example it would be cool to have the mounting frame 3D printed so I would not have to construct it, but that is expensive. I would like to keep the cost below $100/unit. Lower would be great
o So if you think the 3D printing thing is the way to go, maybe you can sketch the design in some 3d software?
• I have basic electronics and programming skills, I can handle the logic for the program but am open to suggestions, schematics etc. I was thinking an arduino or rasberry pi?
• Speed is not important
• Looks are not important
• Does not need to be easy on/easy off and does not need to be manually settible, I'm ok if all setting need to take place through app/phone.
• We have wifi.

I am open to any solution that accomplishes the goal of allowing automation. The winning solution will get me to a functioning prototype as fast and cheaply as possible. I thought about a robot but…
My reference solution ( that you have to beat to be in the running) is a plastic box, held on by magnets with two survoes, controlled by an arduino, with wifi connected to some kind of home automation cloud based solution.

Recommended Skills

Employer Feedback

“good design for me”

Profile image ljsweeny, United States.

Top entries from this contest

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Public Clarification Board

  • anatol33
    • 2 years ago

    I found a more suitable and cheaper servo for my design (entry #2 )- GWS S-125: . It position within 360 deg. and costs about 15 usd.

    • 2 years ago
  • handsketcher
    • 2 years ago

    Please keep contest open until last day as you mentioned here. I'll submit my design at the last moment because the contest is not sealed.

    • 2 years ago
  • ycrow75
    • 2 years ago

    I think the solution
    heating per
    ESP8266 wifi microcontroller(wemos D1 mini) with Modbus TCP / IP
    DHT22 temperature sensor or DS18B20
    Data collection center
    RaspberyPi OpenHab Software with Internet connection
    Cloud services:
    More info or

    I can help the ESP8266 programming and Raspy installation OpenHab!

    • 2 years ago
  • anatol33
    • 2 years ago

    I'm working on it, provide result near the end of competition.

    • 2 years ago
  • anatol33
    • 2 years ago

    Hi, do I understand correctly - you main interest now is the electromechanical part? Programming and electronics you can do by yourself? I have some ideas using servos for RC planes, some of them are strong enough and cheap, about 10 usd, but they need some simple alteration as have the initial angle of turn about 60 deg. only. I can design a 3D printable enclosure incorporating 2 such servos, 2 positioning potentiometers, perhaps end switches and 3D printable parts shaping accordingly to knobs and driving them - if it can be interesting for you. Please give some response - whether you would consider such solution, so I would not spend time for pointless work. And about holding the whole thing in place - would you not consider making it just heavy enough and held by it's own weight? Making correctly shaped parts driving knobs there should be not at all forces lifting it. Just idea... Thanks

    • 2 years ago
    1. ljsweeny
      Contest Holder
      • 2 years ago

      I think you understand the problem correctly. I found many servos go 180 deg (I thought). Re "holding in place", while there are no lifting forces I think there is quite a bit of torque, and the top is smooth, but perhaps you mean something that would wrap around. My fist impression is that positioning potetiometers adn end switches are very complex, I was hoping an integrated servo would do, but I do not know.

      • 2 years ago
  • ranganathp
    • 2 years ago

    Please post as a project and invite me and I can help;

    • 2 years ago

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