I'm in Canada, and our home is a bit older, ~20 years, and the duct work seems to be making a rather loud "pinging" noise at night. I assume this is due to colder weather in general, and the hot air from the furnace heating the duct work up.

The noise, however, does bother my wife, and I'm looking for some advice on how to resolve this. (Currently earplugs are an option we use at times :) ) As I'm a heavier sleeper, it doesn't really bother me though I have heard it. It's not audible during day; there is too much other noise masking it, so I hope that helps understand how "loud" it is.

I never really noticed this in previous houses, so I'm curious as to how "normal" this is, and if there are any "simple" methods for fixing the issue? (I don't really want to call in somebody to replace all the ductwork.)

Is there something simple I can do to reduce this pinging? Is there some simpler task I can hire somebody to do to identify the "problem area" and fix/repair it?