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| Heaternet - Computerised heating controls Traditional Central Heating Traditional central heating often consists of a system of radiator units fed with hot water from a central boiler. The operation of the system is usually controlled by a central timeswitch and electric thermostat. Variations include systems using warm air pumped through ducts to outlets in different rooms. The problem Frequently these heating systems are unable to provide a stable heating effect in the house, some rooms are subject to greater heat loss than others, and the use of a single thermostat means that it is difficult to control the temperature in different rooms. There is a delay between heating the radiators and the effect in the room, a heating element in the thermostat is used to compensate for this, but may under or over compensate. Finally, the temperature of the outside air may affect the rate of heat loss which needs to be compensated for. Mechanical radiator thermotstats are not particularly good The Solution Microelectronics and computers are now very cheap, allowing a much more finely controlled heating system. Each room can be fitted with a small electronic thermometer to measure the actual room temperature, each radiator can be fitted with electronically conrollable valves. The vents of warm air systems could be fitted with electronically controlled actuators. These electronic devices can then be connected to a central computer, where software is used to monitor and optimise the heating system. Progress I built several small 3 component digital temperature sensors, these connected to a PC via the parallel port, and measured the temperature using a small programme running under DOS. I have not been able to locate a supplier of electronically operated valves suitable for radiators, meaning some engineering would be required to motorise normal valves. Software Features The benefit of building a control system in software is the huge degree of flexibility that can be built. It would be possible to implement a seperate group of time-dependent settings for each room under control. A temporary 'boost' override could be added Intelligent features could be added that could monitor the affects of heating, so that the correct compensation can be made for the time delays in the room. Further compensation for rate of heat loss could be added based on a measurement of outside temperature. Other Notes The main control system would be based on software running on a PC, but this is too intrusive for day-to-day control, so an alternate room-based control could be used possibly based on a touch-screen Palm PDA, which could provide both a rich and simple user interface. A commercialised system would most likely run from a dedicated microcontroller-based system or small single-board computer |
| Design by Ed Maher 2002 |