OpenTRV: Better Heating and Saving the Planet

OpenTRV project leader Damon Hart-Davis started in electronics when his dad got him interested early on in life. He has dabbled in computing in finance and with start-ups and an MSc, and is now spending a lot of time on energy efficiency to help reduce the effects of climate change.  We asked Damon to introduce the OpenTRV project to Automated Home Readers…

My motivation for starting the OpenTRV project this year was saving energy and thus CO2 emissions and increasing comfort and ease of use of heating at home, and maybe a hankering to reactivate my old X-10 system and tie this in.

There was a “smart heating” workshop at DECC (the UK’s Department of Energy and Climate Change) at the end of 2012 to try to find ways of radically improving the energy effiency of (ie reducing CO2 emissions caused by) housing in the UK, the vast majority of which will still be in use for the next 40 years. Most participants agreed that some sort of retrofit ‘soft zoning’ system, eg where each room is controlled by its own thermostat and may be able to respond intelligently to occupancy and other factors, was a good idea.

opentrv prototype

The OpenTRV project is an attempt to fulfil that, creating a reference system that can be a simple fit to an existing central heating system with radiators, and that is open source hardware and software and protocols from valve pin to boiler. Interoperability with off-the-shelf components (such as wireless TRVs) and open protocols and the ability (though not a requirement) to interact with OpenEnergyMonitor and home automation (X-10/HomeEasy/etc) is also an important goal. The licensing is permissive (Apache 2.0) to try to encourage manufacturers to use what we develop and be compatible with minimal legal hassle.

The project team has, in a very short time, with many of the members not previously knowing one another and coming together on-line, designed and assembled a “V0.09” prototype which is running in my own home, and for which a PCB is in fabrication. This is based on the PICAXE 18M2+ and has nodes controlling the local radiator in my study, the living room and in the kitchen, where that OpenTRV node also turns on the boiler on behalf of all three nodes, ie if any is below target temperature and has opened up its local radiator valve.  (The aim is to have a parallel stack on ATmega/Arduino too.)

Currently the system is using Conrad FHT8V wireless radiator valves, though we aim to produce our own direct physical valve control too, and we have started 3D-printed prototyping of the mechanical fittings.

opentvr pcb

PCB Layout

A couple of MSc students at a London university will be working on aspects of OpenTRV and related issues for their thesis over the spring/summer and we hope to have a more rounded offering “V2” by winter 2013 for more people to try out in their homes, and for institutions such as DECC to evaluate to see if such controls really do save energy. Another local university group is interested in using a version adapted for data collection to help show people where energy is being wasted in unoccupied rooms for example.

My home (2 adults, 2 children) uses about 1/3rd the typical energy for heating with the help of the old mechanical TRVs and not heating rooms we’re not using (eg keeping doors shut!) but I’m hoping that OpenTRV will make the process smoother and deliver better comfort and more savings. I suspect that most UK residents could halve their heat demand without too much effort or cost and I think that OpenTRV is the sort of simple tool that might help them so do.

Follow us @OpenTRV on Twitter, we’re having fun!

You can visit the OpenTRV project home page at

Want More? – Follow us on Twitter, Like us on Facebook, or subscribe to our RSS feed. You can even get these news stories delivered via email, straight to your inbox every day

2 Comments on "OpenTRV: Better Heating and Saving the Planet"

  1. Mr P.Slater | May 7, 2013 at 8:47 am |

    I believe you are heading in the right direction and as an early adopter of industrial automation, the home-brew approach for those capable of doing it, will be better in the long run than the usual Honeywell dominated secretive solutions. I have thought for a long time that the single room thermostat controlling a boiler, plus TRV’s is a poor solution and that ideally, each room should be equipped with a thermostat with it’s own link to the boiler. Feedback with user data is essential and is the approach that I am taking. Good luck.

  2. Majaz Khalid | December 22, 2013 at 6:38 pm |

    i need help on arduino. i am trying to measure the temp without success.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.