How I Made My Heating Smart Without Damaging Or Replacing Anything — February 1, 2020

How I Made My Heating Smart Without Damaging Or Replacing Anything

I’ve previously mentioned that I wanted to upgrade my heating system so I could program it with more complex timings or control it form my phone. But there’s a catch: The house is rented, so the whole system must do no damage, be made only of removable parts and be installed without modifying any of the existing infrastructure.

In this post, I’ll talk about how I managed it, how it works and what the current state of the project is.

Background

My electric heating is controlled by a Timeguard RTS113 mechanical timer located awkwardly in a kitchen cupboard; it consists of a large outer ring that rotates once every 24 hours. On this ring, you push in red (on) or blue (off) plastic pegs (called tappets in the user manual) at the time you want the heating to turn on or off. As the peg passes a control spindle (representing the current time in the bottom right) it pushes it around approximately one eighth of a turn. Each eighth of a turn of the control spindle, toggles the heating on or off.

A second inner ring allows you to suppress the morning or afternoon schedule for a given day in the week. For example, you can have the heating come on at 6:00am and 7:00pm every day, except on Saturdays where it does not come on at 6:00am because the morning schedule is suppressed.

This works reasonably well, but it’s not very flexible – you pretty much a to live your life on the same schedule every day – if you deviate from it the heating is either wasting power while you’re out, or you’re freezing and have to reach into the cupboard to press the override button.

I’d love to have a smart thermostat such as Nest or Hive but they don’t support my electric heating and as this is a rental house, I’m not able to modify anything to support them.

What I Wanted To Do

The control spindle that is rotated by the pegs has a small slot on the top that can be turned manually using a screw driver to toggle the heating on an off. I can remove all of the pegs and use a stepper motor to very gently turn the spindle each time I want to change the heating state. I could then connect this to a controller that receives instructions from the internet, and write whatever software I wanted to run the schedule.

The Motor

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New Project: Zero Damage Smart Heating in a Rental House — December 21, 2019

New Project: Zero Damage Smart Heating in a Rental House

This is the first post in a series documenting my attempt to build a smart heating system for a rental house. Further posts will follow as I work on it.

I have electric heating in my house, powered by a central timer from the past. The timer is a masterpiece of engineering, but is incredibly crude by modern standards. I’d love a connected system such as Nest or Hive but these systems only support low voltage trigger systems found with most gas systems, not the high voltage switching I have.

So I want to build my own, It’ll be fun, educational and greatly improve my quality of life in the winter. There’s just one thing though: I don’t own the house, so whatever I do must be easily reverted / removed / undone. Also, I’m a software not an electrician so, in the name of safety, I am not re-wiring anything or changing how it currently works.

The Timer

The timer is a Timeguard RTS113, it supports switching the heating on or off once every 30 mins by inserting a red (on) or blue (off) tappet at the appropriate time. On an inner ring it supports suppressing this schedule for the morning or afternoon for any day in the week. For example, you can have the heating some on at 6:00am, and 7:00pm every day, except on Saturdays where it does not come on at 6am.

The tappets are attached to a rotating dial, which rotates once per 24 hours. Each tappet has a lug, that as it passes a control spindle, pushes it around an 8th of a turn. As the control spindle is rotated it toggles the heating on or off.

The Plan

The control spindle has a plastic screw slot on the top to help you see its current state when programming the timer. So, in theory, I can remove all of the tappets and turn the control spindle manually (and very gently) using a stepper motor each time I want to turn it on or off.

Proof of Concept

I picked up a suitable looking stepper motor and motor controller from The Pi Hut, and hot glued a washer to the end. By holding this in place I was able to turn the heating on an off by rotating the motor with an Arduino. Now to figure our a more permanent arrangement…

Next Steps

I’ve already used Tinkercad and made a driver head to fit over the motor shaft and engage with the timer’s control spindle (replacing the hot glue blob from the proof of concept), I’ll 3D print this and see how it goes. Then I need to design some kind of support to hold the motor in the correct place so I can let go of it.

The above gif was made using Paint 3D ❤️

Monitoring My Indoor Air Quality — November 29, 2019

Monitoring My Indoor Air Quality

In my last post I mentioned that I also wanted my info display to show the current indoor temperature, read from the air quality monitor that I made. I built the air quality monitor a couple of years ago – it was my first experience playing with an Arduino and was a lot of fun (interspersed with moments of utterly frustrating confusion). I thought I’d put together a quick intro to what it does and how I made it.

Why Build An Air Quality Monitor?

I saw an advert for an attractive little box that you put on a shelf that monitors the air quality in your room. It has an app to view the data and send you push notifications if it the air was too unhealthy. I loved the idea – I’m a big tracker of data (I once had to log of every single ingredient of every single product I ate for an entire year) and thought it would be really interesting to find out what my environment in my house is like.

I considered buying it… I really did. Then I decided I could totally build my own. I started by buying some sensors:

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Building an eInk Info Display For My Living Room — November 3, 2019

Building an eInk Info Display For My Living Room

Like a lot of Londoners, my trip to and from work involves moving between a few different trains, any of which could be delayed and cause me to be late to work. Or worse – late home. As checked the tube status on my phone over breakfast one morning, I realised that it would be super useful to have some kind of display in my living room allowing me to see at a glance how my commute is looking before I set off, so I can go a different way if needed.

There are a few options to create a display like this – I could re-purpose a tablet or phone in the technology graveyard drawer, writing a quick and dirty app to run on it. But where would the fun in that be? Sure, it would work but I wanted to learn something along the way. I decided to use a Raspberry Pi and a display of some kind, but if its going to live in my house, it needs to be pretty.

I ordered the Primoroni Inky wHAT – an eInk display with all the headers to screw it directly onto a Raspberry PI. It even has Python library for displaying stuff. I went for the two-colour red/black model; I thought I could use the red mode to make any tube status issues stand out.

Features

As soon as I’d ordered the screen, I started thinking about what I would use it for. I came up with a few things I wanted to do:

  • Display the current tube status of the most useful tube lines
  • Display the current weather / temperature outside from DarkSky
  • Show the current indoor temperature, pulled from my Air Quality Monitor (I built this a couple of years back, I might cover it in a later post)
  • Display some kind of indication that central heating is on or off
  • Show the time

I drew this little diagram to get started:

Implementation

APIs

Ever the software engineering project, the first task was to investigate the APIs to give me the data I wanted.

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