wrote in message
oups.com...
: Thanks for your reply. The links you posted are quite useful.
:
: My one question is:
:
: Is it true that a forced air gas furnace loses its efficiency
down to
: 55%, once its 10 years old?
:
: Thanks.
:
No, they do not. The design and components making up a furnace
are such that it either works or it doesn't. Plugged orfices,
leaking ductwork, fan motors, etc etc all wear out but not the
heat producing physics of the materials. If it makes the right
flame, it's still very close to what it originally was.

HTH,

Pop