Steve wrote:

If the furnace is correctly sized, properly installed and
adjusted,

How exactly do you improperly install a furnace?

If you are replacing an existing furnace, one that has been running for
years in a given house and presumably giving satisfactory service, then
how possible can you remove it and "improperly" install a new one in
it's place?

What is meant by improper? That a water line is connected to the gas
input line? That the upstairs thermostat is connected to the furnace AC
power input? That the return duct and output air plenum are connected
backwards?

aluminized steel or stainless....
either will give you a good service life.

How does the correct sizing of a furnace impact on whether or not the
heat exchanger lifespan is impacted by being stainless steel or regular
steel?

90% of those (ECM motor) failures were due to incorrectly designed
and sized ductwork that caused extreme static pressures.

Would these be the same ductwork designed and installed by licensed
contractors?

Would these be the same ductwork that was original to the homes in
question - the same ductwork that somehow didn't manage to dammage or
burn out the motor in the previous furnace - presumably an AC motor?

I'm sorry, but if my 36 year-old AC motor didn't burn out because of the
size of my existing ductwork, then it's a crock of **** that the same
ductwork is the reason why a new ECM motor burns up.

Blame the ductwork. When you have to explain to the customer why his
new $4000 furnace is costing so much repair hassles, blame the ductwork.

Correct term for vsdc motors is ECM. ECM motors are a crock of
****. Best you'll save is 100 watts compared to 1/4 hp AC motor,
and less if you have 2-speed AC motor. Saving 100 watts at 10
cents/kwh is about $100 (that's 100 watts continuously for an
entire year). Now subtract the electricity used by the furnace
otherboard, and various other blowers and condensate pump. The
extra 100 watts used by AC motors are dumped into the house as
heat - which is what you need in the winter (and spring and fall
depending where you live) so it's not all wasted energy.

you need to do some more homework here.

You need to show you're a man by pointing out exactly which of my
statements above are wrong.

I'm right when I say that:

1) ECM motor uses 100 less watts when running full speed compared to 1/4
hp AC motor running at full speed.

2) The extra 100 watts used by AC motor is dumped into the house as heat
during the heating months, so it isin't exactly wasted energy from the
point of view of the home owner.

3) You can't compare the energy usage of an ECM motor running 1/4 or 1/2
speed against a single-speed AC motor. If you want to compare the costs
of multi-speed operation, then you must compare ECM with a 2-speed AC
motor, and you must correctly estimate the amount of time (total hours
per year) that the fan will be running at fractional speed.

Lifespan of ECM motor is 1/2 to 1/4 that of AC motor, and it's
4 to 8 times more expensive (upfront cost of furnace is higher,
repair costs higher). ECM motors create EM/RFI on your household
wiring, can interfere with tv and radio reception.

ECM motors have the same or greater lifespan,

Totally wrong, because you have to factor in the control or drive
electronics that's powering the motor, and when you do, you'll end up
with burned out transistors.

use half the energy to run

The efficiency of fractional horse-power ECM motors are (at best) 60%,
while a 1/4 hp PSC AC motor will have an efficiency of 40% (if running
at full speed). 1/4 horse power is about 186 watts, so an AC motor will
use about 465 watts, while an ECM motor will use 310 watts. The
difference (about 155 watts) would use 1,357 kw hours given a
continuous 1-year run time. If the total electricity cost was 15 cents
per kw hour, then that equates to $200 per year.

Now if you consider the case of a 2-speed AC motor compared with a
2-speed (or even variable-speed ECM furnace) and if you factor in that
in a typical use-case that neither motor would or could be operating for
up to 25% of the time, then the potential savings from using an ECM
motor will almost certainly drop to closer to $100 per year.

Now if you factor in that the 155 watts of extra energy being used by
the AC motor is given back to the house as heat, then you need to
determine what that equates to in terms of cubic-feet of equivalent
natural gas and subtract the cost of that amout of natural gas from your
electricty bill to get the true additional electric cost by using an AC
motor instead of an ECM motor.

While all ECM motors are capable of infinitely variable speed and can be
implimented as such by something as cheap and easy as programming code
in the controller, furnace makers charge a fortune for anything more
than simple 2-speed operation. That is another crock of **** for this
industry.

and are a whole lot quieter than PSC motors.

I could argue that a belt-driven fan with an AC motor with bushings is
quieter than a direct-drive ECM motor with ball bearings.

Only the cheapest manufactures with the cheapest models of
furnaces have issues with RFI. yes you will get what
you pay for.

Or so you think. There's no way that a home-owner (or even consumer
reports) is going to know which units put out RFI, and which units
actually give you what you pay for. Models change all the time - too
fast for independant testing and analysis to have any effect or be
useful for the buying public.

Now tell me how you're saving with an ECM motor.

The average system that I install uses 30% - 40% less energy to run.

Which equates to 155 watts as I calculated above.

So where are we?

Talking about how you need to go back to school, and get up to
speed with the new systems.

Be a man and tell me where I've said anything wrong.

2) Using cheap steel for heat exchangers compared to furnaces from 30
years ago is bad. Using stainless is good.

Stainless is good, but also much more expensive. Will the additional
cost be worth it in your location? Keep in mind that heating and
cooling systems are not built to last forever.

We're comparing 30 - 40 year-old furnace technology with conventional
furnaces. If furnaces cost proportionately more today in terms of % of
disposable income then I should expect no less durability or longevity
compared to the older furnaces. You seem to be an appologist for the
industry by indicating that we should pay more and expect less.

3) Using electronic ignition is bad comprimize from cost/savings
point of view compared to standing pilot light. No real need to
use electronic ignition in modern condensing furnace.

Please explain how this is so??

Because standing pilot lights have been used for decades and have proven
themselves to be reliable, safe, simple, and cheap.

or do you advocate removing half of the safety devices on the
furnace in favor of a standing pilot??

The pilot light and it's thermocouple switch have proven to be an
excellent design in terms of safety, reliability and durability for
residential furnaces. Do you disagree? Do you have the balls to
disagree?

I don't know of *ANY* legitmate HVAC tech that would purposly want
to remove safeties from any gas appliance.

Removing the electronic ignition and replacing it with a pilot-light and
thermocouple does not constitute "removing a safety" device. Get a grip
here.

4) Using ECM motors is also bad comprimize compared to 1/4 or
1/3 hp AC squirrel cage motor. *Actual* or *Net* energy savings
don't justify extra cost and reduced longevity.

Please explain how you come up with this.

See above. Best case savings is $200 a year, typical savings will
almost certainly be less than $100 a year.

Anyone who lives in a climate zone where they expect to use their
furnace at least 5 months out of the year will realize less than $100
savings in their combined electric and gas bill just by having a furnace
with an ECM motor. Anyone who lives in a more temperate climate zone
and runs their fan more often either alone or in conjunction with their
A/C unit will come closer to the $200 in electricity savings.

BTW, I installed a new 3ton, 15SEER heat pump system for a customer

We're talking simply about ECM motors replacing conventional PSC AC fan
motors in residential furnaces. Motors that are part of other
components (heat pumps, A/C compressors, dishwashers, clothes washers,
dryers, etc) are another matter and have different cost/benefit
arguments.

As a consumer, give me the choice of (...)

So you want to go back in time and have your energy bills doubled..

The single largest decrease in my energy bill that the furnace industry
can give me compared to what I have now comes from the 2-stage
condensing heat exchanger. Better airflow design, thinner materials,
stainless, possibly better burner design, etc. All of that comes from
better thermodynamics and materials - NOT ELECTRONICS.

The addition of electronics - particularly the electronic ignition and
ECM fan motor, adds unnecessary cost and complication to the modern
furnace with no tangible benefit to the home-owner and comes with
additional medium to long-term cost of ownership costs and device
down-time caused by component failure.

Technology is a good thing when the contractor/installer/tech
has the training, education, and experience

Screw the contractor. I want a box that will sit there and work year
after year. It's no consolation to me that a repair tech is just a
phone call away. I'll take reliability and durability any day over
repairability. Especially when it comes with lower up-front costs (no
electronics). And in this case, I'm not even sacrificing
repairability. Low tech = high repairability.

to me it sounds like your not happy because its no longer
a DIY proposition, and you can't make it work correctly.

I can install myself any furnace. That's not the point. I'm just
bitching about they choices that furnace makers are making when they
design / build them.

in case you haven't noticed, *EVERYTHING* has electronics
in it these days. The electronics make things safer, and
more energy efficient.

When you have electronic ignition, you HAVE TO HAVE an array of
electronic sensors to make it safe. Having those sensors and
electronics comes with a price - a hit to cost, durability, reliability.

When you have a standing pilot light with electro-mechanical
thermocouple and gas valve, you don't need sensors or electronics,
because it's inherently safe.

FWIW, a good quality digital control can reduce your energy bills

We're not talking about the thermost here. I can have the most
advanced, computer-controlled thermostat I want upstairs to control my
35 year-old furnace, yet still have no electronics *in* my furnace.
Understand the difference?