On 29 Apr 2007 08:54:51 -0700, wrote:

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.

I think the problem is that there is no date on the page. They might
have written it 5, 10, 15 years ago, so that 20 years old might mean
1972!

He the link pointed to by the page
http://hes.lbl.gov/hes/aceee/furnace.html says "The ACEEE List of
Most Efficient Furnaces and Boilers: 1998" so that page is about 9
years old and maybe the other one is too. They mean 1978!

I've complained about this before, that so little on the Net has a
date. One would think the software for writing webpages would at
least put it in the source code, but I've never found it there. Not
this time either. The software isn't designed to put a date in, even
though lots of other software is. And here there is a valid need.

People no longer date their mail. That is, they put a date on a snail
mail letter, but rely on the computer to date email. This is fine
until someone copiess and pastes, or forwards without a dated
attribution line.

When I wanted to find a particular hamfest announcment, I found 6 of
them, all for different dates, and none listing the year. Only
because in this case I knew it was on Sunday was I able to figure out
which date was a Sunday *this* year.

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?