Arduino for Furnace cycle time recording with blower duct wind sensor, Part 1

I needed to record the on and off cycle times of our gas furnace to help me determine whether a new thermostat was working properly or not. So I used an Arduino UNO, a "Lightbeam Interupter" breakout board and a DHT11 temp/humidity sensor breakout board and built a my system. Here you will see, basically, how it works.
Here is Part 2:
• Arduino - Furnace ON T...

[@gorak9000]

Which thermostat do you have? I also have a cheapie honeywell thermostat (the one that came with the house) and it seems to have a rather short dead band as well

[@frenchcreekvalley]

I have the Honeywell Home T1 Pro, model # TH111OD2009.
The user manual that came with it is absolutely terrible. The installation manual isn't much better.