On Thu, 9 Dec 2010 05:42:21 -0800 (PST), wrote:

On Dec 8, 5:53Â*pm, wrote:
On Wed, 8 Dec 2010 10:14:48 -0800 (PST), Mark
wrote:

You need to read the entire study at:
http://www.nrc-cnrc.gc.ca/obj/irc/do.../nrcc38443.pdf

yes anyone interested in this subject should read that...

and take note that the study system had the blower running 100% of
the time. Â*When the furnace was not heating, the blower ran for
circulation. Â*and the ECM motor ran much sloer in circ mode compared
to the standard blower so there was much less circulation and not
surprisingly less energy was used.

The blower speed was adjusted to provide the most efficient heat
transfer - and actually the best air flow as well. Running a squirrel
cage fan too fast can actually REDUCE circulation. I think that was
also explained in the article. That's also why restricted ducting is
such a big deal.



But if you turn the blower OFF when the furnace is off like most real
people do, then it is less relevant.

MOST people turn the blower off???
Not up here. Running the blower on low speed keeps temperatures even,
and makes the air filter a lot more effective.

I would bet 90%+ of the HVAC installed in the USA runs the blower only
when
the furnace is heating or the AC is cooling, not 24/7. In a typical
house with an
unfinished basement or crawl space, I would think running it
constantly would be
a significant waste of energy from two standpoints. One is that it
obviously uses
a lot more electricity. Second is that while circulating all that
air around you are
running it through the basement or crawlspace, attice, etc that is
unheated and
you are losing heat through the duct work on each pass.

With a properly designed system, I don't see the need for constant
circulation.



You don't see the need for it, but the VAST majority of new furnace
installations in ontario are set to run the blower on low, constantly.
All 3 contractors we contacted for quotes for my daughter's furnace
(multi-story condo) strongly recommended it.






and also note the part where the ECM blower caused gas consumption to
increase..

That was also explained - and I mentioned that in an earlier thread -
the higher efficiency of the blower means more gas is required - but
the cost per therm using gas is a lot lower than the cost per therm
for electric, so it is still a net saving.

I would say the facts are presented in this paper but the writer
slanted the conclusion Â*in favor of the ECM.

Follow the money...

In the case of the National Research Council there is no money to
follow. They are neutral, and not funded by manufacturing or marketing
companies.



From the research I've done, I've concluded that the ECM motors are a
mixed
bag. In a typical house like mine (note that means running it only
when heating/cooling),
you might save 20% on electricity. I would pay some extra $$ for
that. However compared
to a regular motor, you have the issue of potentially higher repair
cost, ie $700 bills instead of
$100 due to the increased cost of the motor as well as the electronics
to run it.