wrote in message
ps.com...
On Apr 29, 11:03 am, "Buck Turgidson" wrote:
Don't know what vintage you are talking about, but I've never seen a
furnace with an exhaust blower that was only 60% efficient. Even a
run of the mill, cheap gas furnace has been 80% for decades. And
they have a lifespan of about 25 years.

http://hes.lbl.gov/hes/aceee/afue.html

Interesting site. They claim:

"If your furnace is 20 years old or more, it probably has an AFUE of
just 50 to 60%. By 1990, the typical efficiency had risen to 80%. Some
models today have an efficiencies of 95% or higher!"

So, from 1987 to 1990 the typical new furnace went from 50-60%, to
80%? I don't find that credible.

And if that ain't bad enough, how about this gem:

"The highest efficiency models can cost a little more up front, but
you'll save on fuel bills. You may have to shop around; some
installers may charge as little as $100 more for the high-efficiency
models, others charge a lot more. "

Anybody find that credible?




Maybe not an accurate statement, but that doesn't necessarily make it
un-credible. A lot of people make statements without 'doing the math' - and
many fail to realize 1990 was almost 20 years ago! And there were some
pretty quick improvements to furnace efficiencies on the late 80's if I
recall.

I do agree that if this is really the exhaust blower that is going out then
it is probably higher in efficiency than 60%. And if so, replacing with a
new higher efficiency unit would probably not be justified in the fuel cost
savings.

Have the unit checked out by a reputable company. They would be better at
giving you feedback on the replace vs. repair cost, and if you end up
replacing they will probably apply the cost of the service call to the
replacement cost.