The throat is the gap between the top of the fireback and
the back of the lintel.
I think it's much more likely that you have some sort
of restriction in the flue. Seek advice from a chimney
sweep, unless that's who told you it was the throat.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.