Hi,
I just got this working from end-to-end today, and it's still very crude, but demonstrates the concept.
This uses an 18M2+ PICAXE+DS18B20 to sense temperature* and control a wireless thermostatic radio valve (via an RFM22B) to regulate room temperature with a very simple 1-button / 1-LED UI to select between "warm" (~18C) and "frost protect" (~5C) modes.
This system also has an identical boiler-control board eavesdropping on the radio transmissions to the TRVs and if any of them is set to anything other than fully closed, the boiler is switched on (via an SSR on the two-wire thermostat connection).
The net result is the ability to control temperature room-by-room, getting heat just where you need it (providing you keep doors closed!) not for the whole house. Energy (and thus money and CO2) savings could be substantial.
There is already commercial kits to do this, though all proprietary and arguably overpriced, and not easy to integrate with other stuff.
But OpenTRV already has a the ability to set back room temperature when no one is in the room.
*This design senses ambient light levels; if it's too dark for anyone to be awake and active, the target temperature is set back (lowered) by 1C, nominally enough to save 8% of heating demand in the UK.
See a snapshot of hardware and software here:
http://www.earth.org.uk/OpenTRV/snapshots/20130226-r594/TestFHT8VBoilerNode.bas
http://www.earth.org.uk/OpenTRV/snapshots/20130226-r594/teststub.out.bas
http://www.earth.org.uk/OpenTRV/snapshots/20130226-r594/DHD201302L0.out.bas
http://www.earth.org.uk/OpenTRV/snapshots/DHD201302L0-r429.pdf
(Or nominally here https://sourceforge.net/p/opentrv/code-0/598/tree/trunk/PICAXE/DHD201302L0/snapshots/20130226-r594/ but I can't see what I expect to there at the moment.)
With a photo or two here:
http://gallery.hd.org/_c/energy-matters/_more2013/_more02/OpenTRV-prototype-20130220-V0p09-PICAXE-18M2-microcontroller-DS18B20-temperature-sensor-DS1306-RTC-RFM22B-radio-LDR-USB-powered-on-stripboard-closeup-4-DHD.jpg.html
Rgds
Damon
I just got this working from end-to-end today, and it's still very crude, but demonstrates the concept.
This uses an 18M2+ PICAXE+DS18B20 to sense temperature* and control a wireless thermostatic radio valve (via an RFM22B) to regulate room temperature with a very simple 1-button / 1-LED UI to select between "warm" (~18C) and "frost protect" (~5C) modes.
This system also has an identical boiler-control board eavesdropping on the radio transmissions to the TRVs and if any of them is set to anything other than fully closed, the boiler is switched on (via an SSR on the two-wire thermostat connection).
The net result is the ability to control temperature room-by-room, getting heat just where you need it (providing you keep doors closed!) not for the whole house. Energy (and thus money and CO2) savings could be substantial.
There is already commercial kits to do this, though all proprietary and arguably overpriced, and not easy to integrate with other stuff.
But OpenTRV already has a the ability to set back room temperature when no one is in the room.
*This design senses ambient light levels; if it's too dark for anyone to be awake and active, the target temperature is set back (lowered) by 1C, nominally enough to save 8% of heating demand in the UK.
See a snapshot of hardware and software here:
http://www.earth.org.uk/OpenTRV/snapshots/20130226-r594/TestFHT8VBoilerNode.bas
http://www.earth.org.uk/OpenTRV/snapshots/20130226-r594/teststub.out.bas
http://www.earth.org.uk/OpenTRV/snapshots/20130226-r594/DHD201302L0.out.bas
http://www.earth.org.uk/OpenTRV/snapshots/DHD201302L0-r429.pdf
(Or nominally here https://sourceforge.net/p/opentrv/code-0/598/tree/trunk/PICAXE/DHD201302L0/snapshots/20130226-r594/ but I can't see what I expect to there at the moment.)
With a photo or two here:
http://gallery.hd.org/_c/energy-matters/_more2013/_more02/OpenTRV-prototype-20130220-V0p09-PICAXE-18M2-microcontroller-DS18B20-temperature-sensor-DS1306-RTC-RFM22B-radio-LDR-USB-powered-on-stripboard-closeup-4-DHD.jpg.html
Rgds
Damon
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