Monitoring room temperature at home

2 minute read

My current project is to monitor the temperature of several rooms in my house. I want to be able to visualise the tenperatures in the cellars, bedrooms, kitchen and TV room.

This idea originates from the “less-than-perfect” performance of our thermostat. I woke up a few times recently to find that the girls’ Gro-egg was displaying 14°C. The central-heating had not been triggered by the wireless thermostat located near the front door. After a bit of investigation, it turned out that the radio-frequency signal was not reaching the receiver connected to the boiler in the cellars. Since we didn’t have this issue last winter, I suspect that either the devices are degrading or there is some interference from another transmitter. Perhaps the new wireless bridge I setup earlier this year or something our new neighaours have installed.

Anyway, I had then decided to make it a little project to replace these failing devices by something a little smarter, probably involving a couple of Raspberry Pis. So I divided the project into 2 rather arbitrary phases:

Phase 1: - to accurately measure temperature at several locations throughout my house using low-power unintrusive sensors. - collate data centrally and display in cacti

Phase 2: - to replace the thermostat and receiver I have now. The new solution will need to be more modern, more programmable and obviously aware of the temperature in all the rooms monitored. - investigate feasability of centrally controling indidvidual radiator valves in each monitored room.

I am fully aware that I could most likely get a commercial solution that would fit the bill. But the aim is also to learn a few more technologies along the way. I’m keen to make use of free and open source technologies I have never used before, such as docker, mongodb, nodejs and IOT to name but a few.

So I came up with the following proposed architecture - temperature sensors built around ESP8266 and DS18b20. - Sensors will regularly send temperature data to a web service hosted on the house server. - Web service will consist of 2 docker containers: - mongodb to provide easy key/value storage - nodejs to provide web interface which will store the data provided by the sensors into the mongodb - Cacti will query the web service to get the latest room temperatures and store it into rra files.

I will make my best to document all the steps required to build the above system in this blog.

Thanks for reading.

t.

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