On Mon, 06 Dec 2010 09:29:03 -0500, mm wrote:

On Sat, 04 Dec 2010 10:15:21 -0500, Jeff Thies
wrote:

On 12/4/2010 9:01 AM, Stormin Mormon wrote:
There is a limit how creative furnace makers can get. The same basic
operating principles are used in all brands.

My experience has been to avoid Sears, and Trane. They use off
standard parts, and it's hard to get parts for them. Except to go to
Sears or Trane.

Goodman is the "discount" brand at my parts house. They have fairly
standard parts, and are inexpensive to repair. I've heaed that Goodman
is reasonable quality. The money you save on equipment costs is
signifigant.

Many folks have written that the installation is the important part.
Ask your friends and coworkers who they use. Call the company, and
have them come out for estimate. Avoid companies that manipulate,
pressure, or try to rush you into a quick decision.

Since the new system will be more energy efficient, the company may
reccomend a smaller system. It is very possible that the last company
over sized the equipment. So, the new sytem may very possibly be less
BTU and fewer tons. Many times, a smaller system will provide a lot
better comfort. The old AC may have a name plate of 4.5 tons, but
might actually be delivering 3 tons of cooling. So, a smaller system
may be needed.


How can that be? My understanding is that the rating is cooling
output, not BTU input like a furnace.

I thought furnaces were rated on BTU *output*, not input. The input
is mentioned to calculate the efficiency.

Am I right?

The ones I've looked at are rated as BTU input, primarily because they have a
fixed operating point (orifice sizes, pressures, etc.) and the efficiency
isn't well regulated. The burner efficiency can be measured and the BTU
output calculated, though.