On Thu, 17 Jun 2010 16:18:54 -0700, "Nonny" wrote:

We've been looking at homes here in the Las Vegas area and I've
noticed something that seems different from other areas where
we've lived. In many of the newer homes we've visited, there are
2, 3 and even 4 furnaces, each with split A/C units; I would have
expected to find just 1 or perhaps 2 units and then zone dampers.
Which would be considered to be a superior system?

Single or two story?

A local fireman (Captain) built 5000 s.f.. single story with just two
AC units. The master side had a separate unit and the children /
guest side had a unit. It was "zoned". (multi t-stats) He did the
same for _three_ tank less water heaters -- a heater for the kitchen
demand (zoned) (Hendersen, NV).

One thought is that its possibly considered more energy efficient
to install (4) 2-1/2 ton to 4 ton units than to install a couple
4-5 ton units and then have dampers up in the attic, where it's
both hotter than Hades and difficult to reach for maintenance.
Could this be possible? I find it difficult to believe that
purchasing and installing 4 furnaces and A/C units is less
expensive than one or two larger ones with zoning.


If you write children's book, four units may be needed for such a
large home (Las Vegas)

Would a system with 3-4 individual, smaller, units give better
humidity control (hint: it's 6% RH here today), better energy use
or better energy management? The systems we've seen are all on a
typical VAR meter and not a TOU/Demand meter.

What gives?

Nonny