3 ms·

I had been thinking of buying a Nest, now I think I'll attempt to build my own using a Raspberry Pi. There are some very inexpensive bluetooth beacons that sup

I had been thinking of buying a Nest, now I think I'll attempt to build my own using a Raspberry Pi. There are some very inexpensive bluetooth beacons that support temperature measurement... Does anyone have ideas for cool hardware or algorithms for something like this?

elliottcarlson 11y ago
http://makezine.com/2014/02/03/nest-thermostat-inspires-diy-open-source-versions/ http://makezine.com/2014/02/03/nest-thermostat-inspires-diy-...
brandmeyer 11y ago
Digi-Key is your friend. Build yourself a daughter card with a bunch of relay driver IC's and 24VAC relays. Bare minimum is three, but there are several different arragements for home HVAC, and more doesn't hurt. Some high-SEER rating HVAC units also have multiple speeds. Say, 6-8 relays for some flexibility. Check behind your existing thermostat and see how many wires it gets to be sure. Most units just use bang-bang control around some known limits. Something I've always wanted to try is to have a "periodic recirculation" mode for the times that I'm relying on passive solar heating, just to turn over the stratified air.
- grandalf 11y ago
  Great ideas. > Something I've always wanted to try is to have a "periodic recirculation" mode Yes! That is one thing I want to try too. I did an experiment in an office setting during summer where I found that if set on "auto" someone would inevitably turn the thermostat down to 65 to cool some spot that was in the sun or where the air had gotten too warm. When I switched the fan to "always on" I would set the thermostat to 70 and nobody would feel the need to adjust it. I suppose depending on the cost of running the compressor vs the fan my approach may not have saved money, but it was interesting to see the difference in comfort offered by both.
- jsight 11y ago
  The Ecobee3 can be programmed to run the fans for a configurable amount of time every hour.

elliottcarlson 11y ago

http://makezine.com/2014/02/03/nest-thermostat-inspires-diy-open-source-versions/ http://makezine.com/2014/02/03/nest-thermostat-inspires-diy-...

brandmeyer 11y ago

Digi-Key is your friend. Build yourself a daughter card with a bunch of relay driver IC's and 24VAC relays. Bare minimum is three, but there are several different arragements for home HVAC, and more doesn't hurt. Some high-SEER rating HVAC units also have multiple speeds. Say, 6-8 relays for some flexibility. Check behind your existing thermostat and see how many wires it gets to be sure. Most units just use bang-bang control around some known limits. Something I've always wanted to try is to have a "periodic recirculation" mode for the times that I'm relying on passive solar heating, just to turn over the stratified air.

grandalf 11y ago
Great ideas. > Something I've always wanted to try is to have a "periodic recirculation" mode Yes! That is one thing I want to try too. I did an experiment in an office setting during summer where I found that if set on "auto" someone would inevitably turn the thermostat down to 65 to cool some spot that was in the sun or where the air had gotten too warm. When I switched the fan to "always on" I would set the thermostat to 70 and nobody would feel the need to adjust it. I suppose depending on the cost of running the compressor vs the fan my approach may not have saved money, but it was interesting to see the difference in comfort offered by both.
jsight 11y ago
The Ecobee3 can be programmed to run the fans for a configurable amount of time every hour.