Heater help, 120+volts when unplugged

[Danefoggy]

I turned on my home heater/furnace (gas) for the winter and could hear it click but it never ignited. The blower did eventually come on but it was cold air so I turned it off. I called my normal hvac company who spent almost 7 hours trying to troubleshoot the problem. He indicated he got shocked when he touched the unit and was registering 120+ volts in areas that should only be 24 volts. He said it was a ground issue somewhere in the hvac system and that was why the unit wasn't working properly. I called a good friend who owns an electrical company and he sent out two reps. They checked the ac unit, heater and the heater plug/outlet and said the transformer was bad on the heater and that was the issue. My friend recommended I try another hvac company for the repair. I called the new company and told them the electricians felt it was a bad transformer. A technician came out to verify and was also shocked when he touched the unit. He said it was not the transformer it was actually the control board. However, he said the other concerning issue was with the power cord to the heater unplugged, he was still getting just over 120 volt readings on his tester when he probed different contacts on the unit. He could not figure out why this would happen so he left it unplugged and said I needed to try the electrician again. If I knew replacing the board would get the heat back I would do it, but I am concerned that the high voltage may have caused the issue and would hate for the board to go out again. If replacing the board gets the heat back and doesn't go out again, there is still the issue of the high voltage which is concerning. Do you have any suggestions?

[Admin]

You should turn off every circuit in the house until you find the one that is energizing the furnace cabinet.  Likely you have a bad neutral wire or a bonding issue.

[Danefoggy]

Thank you for the fast reply. I know nothing about electrical. Can you please elaborate on the neutral wire / bonding issue? Like are you suggesting another circuit at the circuit breaker panel could be energizing the unit somehow? The potential issue with the neutral, is that at the furnace itself?I'm just trying to better understand how this could happen out of no where.  Plus I also want to have more information to provide to the technician. I really appreciate any guidance as this has been a very odd situation that no one can seem to figure out.

[Porcupinepuffer]

A properly trained and skilled HVAC tech would have figured this out. Wire pullers (electricians) often don't have the electrical troubleshooting skills an HVAC tech is supposed to have.

[Danefoggy]

Porcupine: that's my problem. I've had out/asked 3 hvac technicians and 2 electricians and no one can figure it out. What is your suggestion? I don't know what else to do.

[Danefoggy]

Just I'd jump on again to see if anyone has any additional suggestions or thoughts. Thank you so much!