Hi,
My 9 year old(installed in '94) Carier furnace is still working like
new. HSI was replaced 2 years ago which was only trouble I had.
Tony


Steve wrote:
In my opinion the only thing your going to gain from a new furnace it a bit
more sophisticated combustion controls and a new warrantee.. You may also
benefit from the fact that if something doesn't work properly on the totally
new installation, your installer and the OEM are totally responsible,
without dispute.

Selling you a new furnace just increases the AC installers profit margin and
simplifies his installation a bit..

But to answer your question, I would say 20 years is the outside limit on a
furnace.. There are a few elements in the combustion chamber that can burn
out but these can be replaced. Combustion controls have go to electronic,
but the old electrical stuff has worked fine for a long period and could be
depended on into the future or that could be up dated in an older unit.

The only time I would recommend upgrading is when someone has a furnace that
dates back to the 50s where fuel was very cheap and efficiency was not a
factor in the design. Anything from the late '70s on will be built with a
much higher efficiency and reliability.