116 lines
6.6 KiB
ReStructuredText
116 lines
6.6 KiB
ReStructuredText
Neighbor's Water Heater Automation (part 1)
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###########################################
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:author: tyrel
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:category: Automation
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:tags: automation, c++, esp8266, servo, stepper
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:status: published
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The Setting
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~~~~~~~~~~~
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My neighbor has a Bosch tankless water heater he put in last year.
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This water heater has one slight problem that when the power even blips a single second, it gets set back to its lowest temperature of 95°F.
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My neighbor (we'll call him Frank for this post because Frank Tank is funny) Frank wants to set his heater to 120°F in his house.
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The problem arises in that his water heater is under the house in his crawl space.
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Without an easy way to set his temperature, he needs to crawl under his crawl space and turn a dial *EVERY. SINGLE. TIME.*
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He asked me if I knew of anything off the shelf that would help.
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I did not.
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So I said the only logical thing someone `like me <https://tyrel.website/wiki/HomeAssistant>`_ would have done.
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"I can totally automate that!"
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The Lay Of The Land
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~~~~~~~~~~~~~~~~~~~
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He has a `Bosch Tronic 6000C <https://www.prowaterheatersupply.com/PDFS/Bosch_Tronic_6000C_Pro_WH27_WH17_Installation_Manual.pdf>`_, with what appears to be a rotary encoder knob to set the temperature.
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I only spent a few minutes under his house while planning this and didn't think to any measuring of how many detents to rotate, or how long the dial took to rotate to 120°F, so my first pass of this project is done with estimations.
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.. figure:: {static}/images/2022/11/04_heater.png
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:alt: bosch heater with a temperature 7 segment LED set to 120F
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:width: 920px
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Project Time - Round 1!
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~~~~~~~~~~~~~~~~~~~~~~~
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I have a few random servos laying around, and an NodeMCU ESP8266 module.
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I figure these would be the perfect solution! ... note: was half right...
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I found some code online by `Kumar Aditya <https://github.com/kumaraditya303>`_ that is for the `two items in my current parts list <https://github.com/kumaraditya303/ESP8266_SERVO_CONTROLLER>`_ (ESP8266 and SG90)
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The Original code runs a web server on port 80, and runs a web page with some jQuery (wow it's been a while) to change the angle of the servo.
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I realized this wasn't what I needed because my servos could only go 180° and I might need to go multiple rotations.
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I found a youtube video on how to make a `SG90 run infinite in either direction <https://www.youtube.com/watch?v=zZGkkzMBL28>`_, so I did those modifications.
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I then modified the front end code a little bit.
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The new code on the back end was actually exactly the same, even though the effect was slightly different.
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It would run on port 80, listen at ``/`` and ``/angle``, but the angle here was more of direction and speed (a vector?).
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The way the servo was built, 160° was "Stop", higher than that was rotate clockwise, lower was rotate counter clockwise.
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I put three buttons on my page that would be "Lower" (150), "STOP" (160), and "Higher" (170).
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I then did some standard debouncing and disabling of buttons using setTimeout and such.
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For a final touch I added in a range slider for "Time".
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This held how many seconds after pressing Higher or Lower, that I would send the STOP command again.
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This seemed to work relatively well, but I figure I should just use a stepper motor if I was attempting to emulate one this way.
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I dug around in my closet and was able to find some parts.
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.. figure:: {static}/images/2022/11/04_servo.png
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:alt: blue case servo with a white arm, cables running off screen. sitting on a desk.
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Project Time - Round 2!
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~~~~~~~~~~~~~~~~~~~~~~~
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I was able to rummage up a `28BYJ-48 <https://components101.com/motors/28byj-48-stepper-motor>`_ stepper with control board, and a `HW-131 power module <https://www.cafago.com/en/p-e8575.html>`_.
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With these I needed a new library so I stripped the c++ code down to its basics, just getting me a server with the index page for the first pass.
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On the Javascript side of things, I then decided I would add a temperature slider, from 90° to 120° (which writing this realize it should be from 95°... git commit...) with a confirmation button, and a small button to initialize down to 95°.
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The initialize button would need to trigger an initialization where I rotate counter clockwise an appropriate amount of time (Length TBD) in order to force the rotary encoder dial to always start at a known state of 95.
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The green submit button sends the new desired temperature as a post.
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Server side, I was using a library called `AccelStepper <https://www.airspayce.com/mikem/arduino/AccelStepper/>`_.
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This I set some made up max speeds and steps per rotation, actual values TBD.
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I added an endpoint called ``/setTemperature`` that takes in a temperature and sets a local temperature variable.
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From there, I calculate the temperature less 95, to find out how many degrees I need to increase by, for now I'm considering this rotations.
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I then apply a multiplier (TBD also... there's a lot of these as you can see!) and call ``stepper.moveTo()`` and it actually feels like it's pretty accurate.
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The endpoint ``/initialize`` runs ``stepper.moveTo`` with ten rotations CCW, and then resets the "known location" back to zero (this also runs on power on for now).
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.. figure:: {static}/images/2022/11/04_webpage.png
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:alt: webpage controls, title "Water Heater Control", a blue slider with a green button saying "Set Temperature: 90", and red "Initialize to 90" button
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:width: 920px
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.. figure:: {static}/images/2022/11/04_stepper.png
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:alt: blue case servo with a white arm, cables running off screen. sitting on a desk.
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:width: 920px
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In Action
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~~~~~~~~~
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The result of this second round of coding is a lot more that I expect to happen once I can finally get down beneath his house.
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Frank will lose power, his water heater will reset to 95°F, the NodeMCU will reboot, and reinitialize itself.
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Frank will then open his browser to the NodeMCU's server, set the desired temperature, and take warm showers.
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Version 2 will come once I actually test EVERYTHING.
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My first quesiton is if a rubber band on a lego tire with a servo wheel adaptor (`which I 3d modeled and printed... <https://www.thingiverse.com/thing:5594405>`_) will work sufficiently.
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Programming wise, I need to figure out how many steps is one degree. Is the rotary encoder one degree per detent? Is it a constant speed? Is it like an alarm clock where you can sometimes jump by 10?
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Stay tuned to find out the exciting conclusion once I can go down below Frank's house.
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.. figure:: {static}/images/2022/11/04_stepper_wheel.png
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:alt: blue case servo with a white arm, cables running off screen. sitting on a desk.
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:width: 920px
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Code
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~~~~
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The code is currently at https://gitea.tyrel.dev/tyrel/frank_tank.git
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