kids wrote:
Just one idea:
I had exactly same problem on Carrier high efficiency furnace last year.
It was 2 stage furnace. During the day normally furnace works on 1st stage,
so no problem there. At night furnace needs more heat so it starts at 1st
stage, then after 12min goes to second stage. As in second stage it worked
quite long to satisfy thermostat next time it starts with 2nd stage right
away.
My problem was that venting of pipes from furnace was not sloping. So some
water was staying in pipes and was freezing. When furnace was starting on
2nd stage furnace computer would calculate that there is too much resistance
in pipes and would shut itself down. Reseting furnace power would start next
time furnace in 1st stage, so it worked.
Re-venting furnace fixe problem.

I am sure this is just one of possibilieites, but I hope it will help you.


No change in our venting. It is, however, much colder than it has been
in previous winters.

I did replace an EXTREMELY dirty furnace filter the day before the
problem started. I can't imagine though, how this would bear on the
situation.