On Fri, 10 Dec 2010 09:50:48 -0500, Home Guy wrote:

wrote:

The new furnace is a multispeed brushless DC motor

They are a heck of a lot more efficient than a crappy split cap
induction motor!!

Sometimes durability and longevity trumps efficiency.

What kind of motor do you think is in virtually every electric or
hybrid vehicle, and the majority of electric cycles???
ECMs are a lot less trouble prone than brushed DC motors. ONE moving
part, no open commutation, no wear, no sparks, no brushes.

Even if electric heat (on a per-therm basis) is twice the cost of
natural gas, that extra energy used by a PSC motor is beneficially used
by my house in the winter, and my PSC fan is running only maybe 25 to
33% of the time, not 100% of the time. In the summer, when my fan is
running more often, it's running at full speed - something that I would
also ask an ECM motor to do, and for which the ECM motor does not have
as much of an efficiency advantage over a PSC motor.

Still has enough of an advantage that I wouls choose the ECM over the
PCM even if I did not choose to run the fan on low constantly.

Hey, it's your choice.
I feel I made an informed choice, and I'm more than happy with the
choice I made. You want to run with 1930's technology, that's fine
with me. I won't twist your arm.
But I also will not agree that the old stuff is always better

So I'll pay the net $100 a year in additional energy cost and never have
to worry about my PSC motor failing me for several decades - if ever.

Even after gov't rebates, forking out a minimum $2000 for a new furnace
is going to take years to recover that, with the ECM motor delivering
just $100 a year and the burners / heat-exchanger *maybe* giving me an
additional $200 a year in savings. And by the time I've made those
savings the furnace will be near the end of it's reliable life-span.

That's fine as long as your old furnace lasts. I wouldn't go out and
spend $2000 (or more) for a new furnace just to get an ECM fan. But I
sure wouldn't cheap out and buy a furnace with a PSC fan motor when
the time comes to change the furnace