I've got an old analogue hour meter on my furnace that basically just counts up the hours that 120v power is supplied to the burner assembly. I'd like to build a data logger that can give me a reading of how many hours each day that the furnace was running, but I'm not quite sure how to get a digital sensor that can tell me how many hours something was running. Does anyone know what such a device would be called, or have suggestions on where I could find one?
An Arduino based logger would detect when the furnace starts running & when it goes off and record the elapsed time.
You can detect whether the burner is running by using a current sensor, as is used in domotics applications to measure power consumption. That's nice since you don't need any direct electrical connectivity to the furnace systems. It would probably be easier though to tap into the signal from the thermostat asking for heat.
You could use a real time clock chip to get a timestamp on the information you want to log and an SD card shield so you have somewhere to write the data.
Adam N
I built just such a furnace logger using a UNO and an Adafruit Data Logger shield which has an integrated RTC and SD card. It was one of my first projects, and using the shield was helpful. I use an LCD display and the biggest challenge of the project was to keep it from getting garbled in a very noisy electrical environment with lots of relays and motors.
The project was a good introduction to programming and the Arduino world for me, but there are other industrial solutions beyond the simple hour meter.
Before I made the Arduinol logger, I was using a Dent Instrument Smart Logger, and I used the Mag Logger placed on a motor.
http://www.dentinstruments.com/media/PDF/SMARTlogger_TOU_datasheet.pdf
But what's the fun in that 