Hi Jdorow,
Thanks for checking it with us. A few questions: what type of Nest Thermostat do you have? In what country are you located? How much power (V) did that extra wire have? You can use a voltmeter to check it. Do you have a voltmeter? If yes, are you comfortable using it?
Voltmeters and multimeters come in two types, analog and digital.
Analog models are no longer common, but they can still be found. They have a needle that moves across a window similar to a speedometer on a car.
Digital models give a specific readout of the exact voltage measured. They can be extremely accurate and helpful for measuring voltage.
When using a voltmeter you should turn the dial or switch to AC. AC current allows voltage to flow through the leads and allows the voltmeter to display an accurate readout.
To check voltage over any R wire: If your breakers are off, you will need to turn them on. On most multimeters, AC current is designated by VAC or V~.
Follow this guide:
- Set the dial to 200 VAC.
- If the multimeter doesn’t have a 200 setting, choose 100 or 250 VAC.
- The general rule of thumb is don’t set it too high (500+) or too low (50).Place the red lead on the R wire.
- Place the black lead on the other wire being tested (W1, Y1 or C).
- The normal readout should be somewhere between 20 and 30 V (24 V is most common).
- Suggestions to keep in mind if you get a very low readout or nothing at all:
- Test it one more time.
- Verify settings on the voltmeter are correct.
- Ensure that leads are plugged in properly.
Please keep me posted.
Best,
Jenelyn
