On Wed, 25 Sep 2019 12:28:17 -0500, Mark Lloyd
wrote:

On 9/24/19 11:24 PM, wrote:

[snip]

I understand there are places that are ignoring the 110.3 violation
and allow cord and plug connection of fossil fuel appliances just
because of the generator thing.

That's what I have here, and it wasn't changed when I got a new furnace
6 years ago.

BTW, one thing I did wonder about, was the (gas) furnace has a fan in
the exhaust.
Forced draft - on all mid-high efficiency furnaces. On a high
efficiency the flue gas is too cold to initiate a draft in the chimney
- and most now just use a plastic vent pipe to the outside - along
with a plastic fresh air intake for the sealed burner.