So this is my first post and I haven't immediately found a link to the forum rules so forgive me if I say/do something I shouldn't.
I have never programmed before so I'm hoping you guys can kind of "bootstrap" me since I need this project like... yesterday.
My room gets really hot, and while I can turn up the AC it's an older dumb thermostat. This means I'm stuck playing with it all day or my room is perfect and everyone else in the house freezes. My idea was to wire some relays in parallel to the thermostat and toggle them wirelesslessly to turn on the furnace fan or if it's really hot force on the AC.
Now to get this done I could interface with my PC but by the time I get all the needed hardware I could probably buy a arduino of some sort.
A couple requirements: I would like to keep the price down in general since I CAN buy wireless thermostats from like honeywell for 100-150 bucks. And the chunk of gear I connect to the furnace should be considered sacrificial and be as cheap as possible.
I like how the first comes with both tx and rx parts. But the second link satisfies the "needs to be cheap/sacrificial" requirement .
Is there some magic involved in making these parts talk to each other or should I stick with the set? Or are these 315mhz parts pretty standard?
Is one of these remote relay boards enough or will I need AVRs at both ends? Would I be able to power steal the 24VDC in the thermostat control line to power the relay board or should I get tons of batteries?
If you guys have any suggestions on what hardware to buy I welcome it. Right now I have nothing and I am have no idea if anything I linked is actually useful for my final build.
What I'm getting here is you have a 3 floor house, and you want to control your thermostat (correct me if I'm wrong). The absolute cheapest way I see you accomplishing this is having a single arduino next to your thermostat, and 3 thermometers hooked up to it, wired to different parts of your house. A step above that would be a seperate arduino on each floor each with its own thermometer, and they all connect up to open ethernet ports and either send their tempature to a server or a twitter account (cheaper). The next level above that could be 3 arduinos with a wireless module all with themostats, and one of those arduinos controls the thermostat. Now as far as wireless modules you could try XBee or something like that, but I don't know much in that field.
Project sounds feasible with 1x arduino in your room doing the temperature monitoring and controlling the remote relay board.
The information on the seeedstudio relay board seems comprehensive enough but finding data on the goodluckbuy RX & TX modules may be difficult. Try and find datasheets for them before committing. Make sure the relays can handle the AC/DC volts/amps you want to switch.
You could build a simple L78S12 voltage regulator circuit to power the 12v relay board from the 24v thermostat supply.
Are other RF devices in the area likely to trigger your receiver relay board, if so then stick with an encoded RX/TX pair of devices
There are other ways to do this using wireless remote switches or wireless stats, but if you fancy an Arduino project this looks like a fun way to do it. Depending how old the house is and how far you are from the stat, you might find it's difficult to get the wireless range. I suppose the only way to find out is to try. For comparison, I'm using nRF24L01 transceivers without amps or external aerials and the wireless range is barely enough to reach an adjacent room. It's not hard to daisy chain them if you don't have enough range to get there in one hop.
If you aren't sure, check the voltage at the stat. Here in the UK they usually switch mains voltage. If you have AC or DC power there it should be possible to generate a 5V supply one way or another as long as you're comfortable dealing with electrics - and I guess you are since you're considering this project.
One advantage of a commercial programmable stat is that they enable smarter control over the heating/cooling cycle. One very useful feature is termed 'chrono-proportional control' which means the unit works out the duty cycle needed to maintain your set temperature and then maintains that duty cycle at a fixed interval (perhaps 20 minutes) rather than waiting for the temperature to cycle up and down. This is far more comfortable. Another useful feature is that they can be programmed to anticipate the scheduled temperature changes and bring the heating/cooling on early enough to achieve your target temperature at the time you specified. This is only relevant if you're planning to schedule different temperatures at different times, which would require an RTC. Maybe consider that for the Mark II?