Thermostat


7 posts
by texasdex » Wed Nov 02, 2011 5:10 pm
One project that I would love to do on the Pi is a programmable, web-interfaced, thermostat. Store-bought network-enabled thermostats tend to run in the hundreds of dollars and have limited options for custom programming. My current thermostat still uses mercury switches. It\'s been done with an Arduino [url=http://diyistheway.blogspot.com/2009/03/thermosmart.html]here[/url] but I think the Pi could do it much better. Just add a 1-wire temperature sensor (or several) and a USB wifi dongle (or get the B model and string Ethernet to it) and you can monitor the temperature and display it wirelessly. Those few GPIO pins that are planned for the Pi will be perfect for control functions: just hook up a few relays to them for the cool, fan, heat, and emergency heat (if you have a two stage heat pump) functions and you\'re golden.

The rest is just software. If I actually get around to doing this I\'ll probably implement it in Python, with a web interface to monitor the temperatures and program it. Depending on the number of temperature sensors I have, I could be as clever as I wanted to, for example monitoring the outside temperature, the output temperature of the vents (which tends to vary depending on heat pump efficiency and outside temperature), and even check the temperature for multiple rooms--if there\'s a major imbalance, turn on the fan only.

Is anybody else interested in this sort of thing? Anyone think I\'m underestimating how difficult this would be?
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by Ecume29 » Wed Nov 02, 2011 6:10 pm
This project is very interesting and useful (like many of the proposed projects).
However, it is difficult to define the various devices before testing Pi.
I do\' not know enough at this time Pi, but I can not wait ...
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by NoSuchNick » Wed Nov 02, 2011 6:21 pm
I\'m planing something similiar, but in a more general direction.
I\'m working on my own home automation project. Currently i have remote controlled power outlets, lights, computers and a stereo system. I also have various temperature sensors scattered around.
I want to figure out the protocol of some of these thermostats you attach to radiators, so i can controll individual radiators (one controll element only costs ~15 Euro)
My base is an arduino at the moment, but i\'m planing to switch to a pi, to make it more intelligent.
An example of my controll interface can be found here:
http://automation.plainpixels.de/demo/info.php
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by johnbeetem » Wed Nov 02, 2011 7:13 pm
Maxim/Dallas has various I2C thermostats/thermometers. I\'ve used the DS1631 in the past; probably better ones are available now.
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by hippy » Wed Nov 02, 2011 11:42 pm
I\'m planning to do much the same but starting with a USB-to-serial cable and using a simple protocol to connect multiple microcontroller nodes which actually handle the hardware sensors. If serial via GPIO is possible, accessible via the chosen R-Pi language as a \\dev\\tty*, then great but if not it will still work, and it\'s portable ( hardware and software ) to any other platform.
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by djsharman » Sun Nov 06, 2011 7:02 pm
I made something like this about a year ago. I wrote the program in php (frontend and control) and it took me about 11 hours in all. Temperature sensor was a cheap USB thing I bought off the web for around €15. For controlling the boiler I pulled apart an X10 unit and mounted the power controller inside the boiler housing. Works nicely and saved me a fortune on heating bills :-).

I am probably going to move this onto an R-pi when I can get my hands on one of the little buggers!

Screen shots :-
Monitoring and control:
[img]http://www.nemtek.co.uk/up/control.PNG[/img]

Timer setup
[img]http://www.nemtek.co.uk/up/timer.PNG[/img]

Ah yes, it must be easy to use as even my technophobic fiancée can manage to use it.

Cheers,

Darren
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by psycho_moggie » Sat Dec 03, 2011 4:47 pm
Have a look at http://www.raspberrypi.org/forum?mingleforumaction=viewtopic&t=1202
You can start development before you\'ve got your Raspi.

I\'ve got a DS1621 temperature sensor on about 1 metre of wire from a VGA connector. Although i2c is only intended for use within a single bit of kit, there are high current drivers which can be used on longer cable runs. I also have an idea for a design which just uses op-amps, so would be cheaper. Watch this space.
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