David A. Bader

THE THERMOSTAT

THE HEATING PROBLEM A heatpump is ineffective when outside temperature falls below 40º. If you forget to switch the thermostat manually, or you’re not at home when the temperature drops your house is without heat. When temperature rises above 40º and you don’t manually switch the thermostat to use the heatpump you’re wasting energy.

What if the thermostat could tell the outdoor temperature? What if I could buy a thermostat that could do this? The extensive search for an off-the-shelf solution. What I found THE IDEA

DO IT YOURSELF You are not alone Many have tried and many have succeeded The information is out there

WHAT YOU NEED TO KNOW A thermostat is just a tiny computer that controls a bunch of relays. Green wire - fan Yellow wire - compressor Orange wire - reversing valve White wire - auxiliary heat For fan, turn on green. For A/C green and yellow. For heat, turn on the green, yellow, and orange. For a aux heat, turn on green and white.

COMPUTER A Raspberry PI model 3B with Wi-Fi + 16GB $43

DISPLAY 7” touchscreen display - $70

SENSORS 2 Temperature/ humidity sensors - $4 each

RELAYS Relay board with 8 relays - $14

WORKING PROTOTYPE Software to tie it all together

SOFTWARE Apache server running on the Pi Climate software reads its settings from an XML file Writes status to an XML file XSL files for both PHP web pages to display status and allow settings to be changed Accessible from any web browser including smart phones and tablets

HUMIDIFIER Used available relays to open damper and turn on water valve No longer manually turn on in fall and off in spring Automatically opens damper and turns on water Automatically adjust humidity based on outdoor temperature to prevent condensation on windows

ZONES Using the Raspberry Pi Zero ($5), a sensor could be placed in every room

COMMUNICATION Each sensor uses same OS and software as main thermostat Main thermostat reads sensor data by accessing XML data on the web site Easy access to devices web pages makes troubleshooting and debugging easy The main thermostat uses the data from each sensor to open and close dampers Each room can be heated and cooled independently

EVEN MORE System can move air from warm rooms to cooler rooms and visa versa by turning on fan and opening and closing appropriate dampers Swap inside air with outside air when appropriate to save on heating and cooling

SUMMARY Devices are plentiful, inexpensive, versatile and extremely well supported Much of the hardware and software is open source Any project you can imagine can probably be built Someone, somewhere has probably already done a small part of what you are trying to do. And they most likely shared their software, hardware and experience on the internet.

Bader Technologies, Inc. P.O. Box Lehigh Valley, PA David A. Bader