Gas furnace will shut off at 69, Thermostat set on 70. Error on furnace says 'Incorrect twinning' check polarity. I have reset furnace and circuit breaker. This has happened 3 times tonight. Janitoral gas furnace. Husband is away with National Guard and cannot be reached on how to fix.:confused:

The cure is to reverse the power leeds if crossed OR better yet is to reverse the 24 volt low voltage supply conductors. If you do not know what I am talking about you will need the services of a on site repair person that know what they are doing.

The circuit board has a glich that is causing this to happen. The board should be OK if the wires are switched as stated.

Is your furnace running on propane or natural gas? If it is propane the may be a low gas pressure switch on the gas line that will give you this fault code if not working correctly.

Why would the wires need switched? It has been working like that for awhile I am sure, can't see where switching the wires are going to do anything

This is right out of the Janitrol/Goodman service manual. Joshdta if you had the manual you would know the answer.

Rapid continuous blinking - Incorrect twinning, incorrect primary polarity. Reverse transformer secondary leads, reverse primary wires.

I don't use manuals just common sense

i don't use manuals just common sence

That is where your problem is to start with. Many items on HVAC are not common sense in nature but driven by the digital age (circuit boards). You better learn to read manuals since all the technology is described by them. The day of taking your best guess/common sense has been over for some time.


While some common sense will always prevail like is the switch turned on questions the circuit boards and other electronic components cause us to use the factory engineering manuals to decipher most furnace troubles since they are not mechanical in nature but presented in a digital/analogue form.

Hope you got this fixed! Did you end up getting a control board??

In my 14 yrs and thousands of service calls I have never once had to reverse wire on a furnace that has worked for years. Maybe if the furnace was just installed and the polarity was backwards then I could see this fault being a issue. Other wise the board is bad or there is anouther problem!!

Does the furnace work at all? If it does, then I agree that it is a bad board. If polarity is reversed, the furnace should not work at all. If it works sometimes, and not others, then your board is malufunctioning(given the code you are getting). Every time I have seen a furnace show the twinning error(when only one furnace in place) it has been a fualty board.(assuming the furnace has worked well up to this point.) Best bet here is to call in a tech. Please let us know what they find. Good day.