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Most dwellings that are heated with radiators would use less energy if the radiators and boiler(s) were intelligently controlled so as to deliver heat only when it is needed — that is, only when the rooms in question are occupied.
Current central heating systems regulate the temperature of the whole house according to the temperature in one location — say, the living room. Sometimes the system limits the temperature in other rooms by means of (passive) thermostatic radiator valves (TRVs). But this is not yet optimal, because (1) rooms may be heated when they are not occupied; and (2) occupied rooms may go unheated if the temperature in the living room has reached the target temperature.
One would like to achieve optimal energy savings without replumbing the whole house. What if we were to fit the radiators with active valves and install a system that controls the active valves and boiler according to room occupancy?
An active valve must have some sort of microcontroller on board that will change the valve's temperature set point. A first step is to program into this microcontroller a temperature schedule corresponding to the expected occupancy schedule of the room. Many such "eTRVs" are already on the market. The next step is to connect the eTRV with an occupancy sensor so that it can reduce the temperature when there's no one around, making in an intelligent TRV (iTRV). A third step is to connect the iTRVs to the boiler controller so that they can tell the latter to supply heat when they need it.
One would like to achieve optimal energy savings without rewiring the whole house, so these connections will have to be wireless.
Damon Hart-Davis launched the OpenTRV project with the goal of making hardware and software available that implements such a system — wireless occupancy-dependent iTRVs with boiler control — the ultimate aim being to facilitate optimal energy savings and comfort.
No existing system offers all the features needed for optimal energy savings, comfort and convenience, and none of the commercial systems is really open. Only an open system can be extended, integrated and continually improved by all parties, without restrictions.
The short term goal is to realize a functional reference system making use of existing off-the-shelf hardware. See the roadmap on the project website.
No, we're not building anything entirely new, but we're building something more open, more fun, more flexible, and ultimately cheaper and widely useable by more of the 26 million UK households ... that need to radically cut their carbon footprint.
Want to learn more about the project? See the project home page, then come back here and
click on Browse Pages to browse the wiki.
See the Glossary for some terminology.
DHD20130414: V0.1 tag, code commissioned on V0.09 PCB for my study/desk: https://sourceforge.net/p/opentrv/code-0/HEAD/tree/trunk/PICAXE/DHD201302L0/snapshots/20130414-r1027-V1p0/
DHD20130404: Mike populated (and tested) the first V0.09 board! https://twitter.com/mikestir_uk/status/319917642435665921/photo/1
DHD20130321: Automated Home write-up: http://www.automatedhome.co.uk/carbon-footprint/opentrv-better-heating-and-saving-the-planet.html
DHD20130312: FHT8V sync implemented so TX duty cycle now ~0.1%, but 18M2+ code space very nearly full!
DHD20130311: Hurrah! First PCB design shipped to fab (and components to populate 7 boards ordered). Mike and Bo have been labouring like slaves for this; many thanks! http://www.earth.org.uk/OpenTRV/snapshots/20130311-r848/
BH20130303: Bo is preparing the first OpenTRV PCB layout in Eagle; thanks! See https://sourceforge.net/p/opentrv/code-0/684/tree/trunk/PICAXE/DHD201302L0/hardware/V0.09-eagle/
BG20130303: First print of an @OpenTRV valve fitting. And it fits! Now I need an M30 connector nut: http://pic.twitter.com/gaIUDsFWyt et voilà: https://twitter.com/brunogirin/status/308251903899340800
DHD20130301: Third node running (second soldered-up, with improved layout and decoupling). http://gallery.hd.org/_c/energy-matters/_more2013/_more03/OpenTRV-prototype-2-20130301-V0p09-PICAXE-18M2-microcontroller-DS18B20-temperature-sensor-DS1306-RTC-RFM22B-radio-LDR-USB-powered-on-stripboard-complete-in-Maplin-N10KH-power-supply-case-closeup-2-DHD.jpg.html
DHD20130301: http://www.opentrv.org.uk/ domain set up for the project.
DHD20130228: Combined TRV and boiler node working; now two soft zones at home!
DHD20130226: TRV node is controlling local TRV and boiler; soft-zoning ahoy!
DHD20130223: Managed to get one board (wannabe boiler node) to eavesdrop on transmissions to the TRV from another board (thermostat node). Not got as far as looking at the content yet!
DHD20130220: V0.09 soldered up on stripboard and running nicely!
DHD20130214: Now controlling boiler directly and TRV via radio for first soft zone prototype!
DHD20130212: Hurrah! Made radio contact with FHT8V TRV so can now (just) control rad and boiler...
DHD20130126: Can call for heat from boiler with SSR in lieu of 2-wire mechanical thermostat (240V).