On Monday, December 22, 2014 11:34:27 AM UTC-5, Danny D. wrote:
trader_4 wrote, on Mon, 22 Dec 2014 08:21:13 -0800:

No, you can reverse the hot and neutral on AC. But as I said before,
it's virtually impossible for that to have happened and I doubt anything
to do with the power to the furnace is the problem.

I agree that hot and neutral *can* be reversed, but, from a practical
standpoint, other than the safety of two-wire grounded items, it
makes no difference.

So, when they're talking polarity reversal in the continuous-blink
scenario, I wonder if they're talking about the DC voltage, where
polarity can make a huge difference.


No, they are talking about polarity reversed at the incoming AC,
ie hot and neutral. How would you ever get DC reversed on the circuit
board?