Unless you can show where someone has made some blower CFM measurements
in a real house, then you have no real evidense to support that
And in any case, an ECM motor has no way to know how much CFM is being
moved by the fan its running, especially as a drop-in replacement for a
And I bet that modern furnaces that come with ECM motors also don't know
how much CFM they're actually pushing. They probably only know
indirectly by monitoring return-air and output-air temperature
difference. Do any of them have an integrated wind-speed sensor?
Then put a number on it.
The home-owner is "often" too stupid ... in some instances. ?
That's a mixed message. You want to say that some arbitrarily large
fraction of home-owners would (or are) choosing a fan-speed that too
high (you'd have to show me how they have any real control over that,
btw) then you back away by saying "in some instances".
You are showing a strange bias against homeowners that is affecting your
ability to think rationally about this.
Yes, let's compare these other situations, where micro-power DC motors
have been used:
So you think that these tiny, micro-power DC motors make for a good
analogy when we're talking about the furnace fan motor market eh?
Tell me how many consumer furnaces were available in 1985 with ECM
And you haven't told me anything to support your claim that ECM motors
Saying that the first ECM motor was made a hundred years ago, or that GE
supposedly actually sold a furnace with an ECM motor in 1969 (which
maybe they withdrew from the market a few years later ?) is not an
answer to why ECM motors last longer (your claim).
Don't change the subject. We're talking about longevity, not
Yes, they run hotter. They are also constantly cooled by the airflow
generated by the fan.
Tell me which motor is more likely to survive constant use in a
high-resistance duct system? Or survive a fan bearing that gets
gummed-up over time? Or a filter that's not properly cared for? Or a
power spike or brown-out on the AC grid?
That depends on how many PSC motors are multi-speed vs single speed.
And you can get high-efficienty PSC motors in the range of 62%, as
And I suggest you also read this:
Any furnace that has a shaded-pole variable-speed fan motor does have
horrible efficiency, and perhaps some people here are confusing
shaded-pole motors with PSC motors in these discussions about motor
It's clear that when we're talking about 1/4 and 1/3 hp single-speed PSC
motors, efficiencies up to 60 - 65% are obviously the norm, and bring us
much closer to ECM motor efficiency than most people think possible.
It's clear that some furnace makers are using puny or wimpy ECM motors
in their furnaces. But none of the HVAC regulars reading this will
chime in and agree.
ECM motors have sophisticated electronics that PSC motors don't have.
When-ever you include additional components into any system or device,
you have more points of failure. You stubbornly refuse to believe that
the electronics in an ECM motor represents an addition point-of-failure
that PSC motors simply don't have.
Ok homer, so when are you going to start you new job with the manufacturers
and/or governing bodies to redesign and reclassify furnaces so that you can
turn a multi billion dollar industry back in time 20 years??
On Dec 14, 12:44 pm, firstname.lastname@example.org wrote:
Excuse me, but I think the points Home Guy are raising are perfectly
valid and you
can't just dismiss them. You claimed that slowing down a fan motor may
not lead to
less airflow. I agree, thatis possible, IF the fan is turning so
fast that it's no longer
moving air, ie cavitation has occured. But that isn't the abnormal
case we're discussing now, is it?
We're talking about a normally operating home forced air funace or AC.
Also, HG raised a perfectly valid question of how a drop in
replacement ECM motor
could learn anything about air flow. It can't directly measure the
CFM being moved.
He asked a question I'd like to know the answer to, which is in new
furnaces with ECM,
do they have air flow sensors?
Also, to add to HG's case, I think all the hoopla about constantly
circulating air 24/7 is
a bunch of BS. Why? Let;s look at my house, which I'd say is
typical. Furnace is in
the basement, returns are uninsulated and some to upstairs even flow
through outside walls.
Those ducts have no insulation, because the wall cavity is used for
the ducts and the insulation
that the normal cavities would have is absent. Also, typical ducting
is far from perfect,
with leaks in botht the returns and supply commong.
So, now I'm to believe that running a blower 24/7
when it's 20F outside, drawing the air through the cold basement, the
cold furnace that is not
fired up, through ducts that are in outside wall, etc, is a smart
thing? I don't care how much
you think you save in an ECM motor. Even if the energy to run the
blower is free, the rest of
the above equation spells loss to me.
On Tue, 14 Dec 2010 11:26:48 -0800 (PST), email@example.com wrote:
It is an all too common occurence when guys who do not understand what
is happening try to "fix" their furnace.
Which someone has screwed around with
In most cases, if not all, no.
Not all basements are cold. A very large percentage of urban
basements are heated, finished living space.
To you it might be.
To me, and many others, it is not.
And I've checked the air temp from the heat outlets on the outside
walls of my house - they are room temperature or better with the
burner not firing
I've stood up for HG on many issues - but he'll never get it. The days
of the model "T" are long gone - and the day of the standing pilot
light, atnospheric burner, PSC fan gas furnace are pretty well gone
Taking all the "advancements" off of today's equipment will not make
it a) last longer b) work better c) cost less long term or d) run
He first argues for resizing the jet - which I agreed with him about,
and adjusting the air dampers, which I also agreed with him on, then
he starts talking about putting the gas valve "between settings" -
referring to the 3 position gas valve as "variable", and adjusting the
flame by adjusting the gas shutoff valve on the 1" iron pipe feeding
the furnace. Sure he can reduce the flame that way - but it is sure
not the right, or even an adviseable way to do it.
On Tue, 14 Dec 2010 16:49:28 -0500, firstname.lastname@example.org wrote:
We've beaten to death "modifying" furnaces to improve efficiency.
It can be done with older furnaces because they just weren't designed
with efficiency as a high priority. The priority was quick heat on
I wouldn't try modifying a modern "efficient" furnace.
Correct sizing is what you want, so more heat goes through the heat
exchanger and less up the stack.
Beyond that - and insulation - I've found the best way to reduce gas
use is to not heat where it isn't needed.
Working vents are important, as are just closing/opening doors.
All depends on where the thermostat is, and that can be moved if it
makes sense to your needs.
I like the idea of zoned heat, though I have no experience with it.
I just close or open vents and doors depending on what current needs
On Dec 14, 4:49 pm, email@example.com wrote:
But here's the problem. You claimed that slowing down a blower
reduce the air flow. If you were taking about the pathological case
where the blower
can't move air because it's cavitating, they you should have pointed
that out. Because
if that's the case, there is a problem that needs to be fixed with the
system that has
nothing to do with an ECM vs conventional motor. To do otherwise is
just to spread FUD.
Who said anyone was screwing around with anything? In the current
discussion, all I saw
was Home Guy asking some very relevant questions about ECM motors,
installed in modern furnaces at the factory.
So then Home Guy's point remains valid. Apparently the motor can't
how much air is actually flowing. Sounds more and more like it's
just a multi-
speed motor that will be more efficient in most applications, ie those
or better ducting. In the typical install, that equates to using 20%
Now, if we don't intend to run our blower 24/7, instead using it only
heating or cooling, how much will that amount to?
The question of course remains if cost is the only issue, with
typical use, will you save enough in electricity to recover the cost?
at quotes where it's $1000 more for a 95%efficiency furnace with a two
burner and variable speed ECM blower, compared to one without those
Clearly all that cost isn't due to the blower
but it comes with it, without choice. Combine that with the exposure
repair cost for the ECM and drive electronics and I'm not sure of the
If you have issues other than saving energy that the variable speed
drive will help with
then it's another story. But for me, I don't see that extra value.
Around here, NJ/NYC area, I'd say the majority are not. My house
I see plenty of new construction where they have dual zone systems,
one furnace in an unfinished basement, the other in the attic, which
worse if you keep air moving 24/7.
Also, not one person that's hawking the wonders of variable speed
mentions the above points. It's obvious I don't have a finished
basement and not
one contractor said a word about it. All of them are spouting mostly
what we call
marketing BS. Like the variable speed blower in a 5 ton AC is gonna
use the same
electricity as a 40W bulb. That the furnace which is still rated at
95% AFUE, just
like the single stage, is now going to be way more efficient. Both of
those are fiction.
There's some truth that the furnace will be slightly more efficient
when firing at 70%,
but from physics and what I've been able to gather, it's a small
percentage, a couple
percent at best. And around here, it's gonna be firing at 70% in the
Fall and Spring,
when I use the smallest amount of energy anyway. So the gas usage
difference is very slight.
You dismissed all the above on the basis that there are lots of
so the heat lost by constantly pumping hot air through cold basements,
attics etc isn't an issue. I say it is.
Explain to us how it's possible to send air through typical ducts in
the outside walls
of homes when it's 20 outside and not have them lose heat. Maybe
the laws of physics. Actually it sounds like you have, since you say
the air coming
out is room temp or better with the burner off. How is it possible
to gain heat?
I can take the two stage complexity and the ECM out by simply choosing
to not buy it and still get a 95% AFUE furnace. And as to repair
has a valid issue. Are you going to claim that the replacement cost
ECM motor or drive electronics is the same as a conventional motor?
seen plenty of stories here over the years of people paying $800 to
If a plain old motor goes, I can replace it for $100. Does that mean
all the technology in today's furnaces isn't justified? No, but IMO
you can't lump
it all together. It's like buying a new car that has headlights that
adjust and react to the cars pitch up or down at any given moment, to
them perfectly pointed evenly ahead. A nifty
feature? Yes. But when that system goes out, it sure isn't gonna
same to fix as a conventional headlamp system.
Mr. Snyder appears to have painted himself into a corner over the finer
details of the operation of ECM motors and seems to just want to walk
away from this conversation instead of admitting he's wrong or
There are several nation-wide HVAC retailers with websites listing
prices for furnaces. I was looking at one a few days ago, and they
listed various Goodman furnaces with various efficiences (from
non-condensing to condensing, etc) and the price for the furnaces ranged
from $750 to $1500 if I remember correctly.
Have a look at these retailers / wholesalers:
See if the furnaces you've been quoted on are carried on any of the
above sites to get an idea of just how much your local contractor is
over-charging you for the hardware.
I have a hunch that just like roofer's who over-charge you for the
shingles, you'll pay a 50% premium for the hardware when you buy an
entire package (furnace + installation) from a local contractor.
Your $1000 difference in the cost of a furnace with and without 95% /
2-stage / ECM is insane. Most 90+ furnaces seem to cost around $1000
judging by what I see on those sites.
See what your contractors say about just installing the furnace that you
buy on-line. See if they balk and weazel their way out of doing that.
Your point about running the fan 24/7 is lost on a lot of people.
Your house loses heat through the walls, windows, and ceiling. Doesn't
matter how much you insulate - the walls, windows, doors and ceiling are
the containment envelope for the heat in your house. You're not going
to loose heat through the wires or the plumbing.
And it's not just the basement walls (that's a red herring).
By running your fan 24/7, you're constantly forcing interior air to pass
against the walls, ceiling, windows and doors, where the air will do
it's best to either pick up heat (in the summer) or dump heat (in the
winter) against those surfaces and tranfer heat to (or from) the
outside. It's in the winter that this heat transfer is particularly of
interested to us.
What you want is to achieve a still-air condition where there is no air
motion inside your house. This condition will result in the least
amount of heat being drawn off the interior objects (furnature, interior
walls, floors, etc) and deposited against your exterior walls, windows,
doors, etc. But with a forced-air system, you have no choice but to
move air around and cause a breeze.
So while running a furnace 24/7 with the furnace dumping exactly as much
heat into the house as the house is losing to the outside is (in theory)
the most efficient way to operate, the very act of moving the air around
inside your house is contributing to heat loss to the outside world. So
it's probably the case that a furnace duty cycle less than 100% is more
efficient at heating your house while conserving interior heat at the
same time. I'm thinking more like 70% is probably where you want to be,
and certainly to NOT run your fan at any time when your furnace is not
Legitmate contractors will not install *ANY* equipment that the customer has
purchased off the internet for 2 reasons.....
1) Manufacturers warranty is null and void for any and all equipment
purchased off the internet.
2) Legitmate contractors cannot and will not assume *ANY* liability for said
I charge what I do, because thats what it takes to keep my companys doors
open, and still make a small profit after all of the costs, expenses,
salaries, and taxes are paid. Here's a hint.....
"The bitter taste of a poor quality installation will linger far longer than
the initial sweetness of a low price."
The finest equipment in the world is worthless if installed improperly.
I'm sure you've come across heartbreaking installations of expensive
systems that some hack put in and you have to break the bad news to a
very nice customer.
I was at a deposition last week where the defendants attorney was
quizzing me about my training and where I got it. Nobody can supply
the training I've had. I started out repairing window units in the
early 1970's and self taught from there. My friends with all the
wallpaper come to me and ask me about this and that because I've
usually seen it. "Experience is a fools best teacher." Emerson. :-)
The Daring Dufas used poor usenet style by improperly full-quoting:
You totally missed the point.
What's wrong with the customer buying a new furnace through one of those
national retailers / wholesalers, and then contracting a local HVAC
company to install it?
How would that result in improper installation?
The customer would save the 50%+ markup charged by the local HVAC
company for the furnace.
Asshole - you really think you get 'wholesale price' like
that ? Yeh, you probably think if a car dealership sells you a car at
'$ 100 below invoice', they lost money on the deal. after all, they
showed you on the invoice 'what they paid for it', right ?
Anyone who is actualy in the business laughs out loud at the
'Internet wholesale' prices for any parts or equipment. It's double
what they pay at the local supply house.
Click here every day to feed an animal that needs you today !!!
Not every HVAC company or HVAC tech is a crook. The crooks are well
known to the repair guys and are hated. The dishonest service people
give everyone a bad name and the good honest service techs get very
upset when hearing about what one of the crooks pulled off. I spent
a couple of hours at a deposition involving a lawsuit against one of
the crooks who vandalized the AC belonging to the elderly mother of
a friend of mine. Those crooks shorted out her compressor and told
her she needed $5,500.00 worth of new system. I wasn't about to let that
happen. The crooks called her out of the phone book with a
$69.95 spring tuneup special which is something a lot of less than
altruistic service companies do to get their foot in the door to take
advantage of the less than knowledgeable customers, especially the
elderly. You can usually spot the crooks by their shiny new trucks.
On Wed, 15 Dec 2010 09:27:48 -0500, .p.jm.@see_my_sig_for_address.com
Sometimes that is true.
HOWEVER - I find quite often I could buy stuff over the internet for
less than I pay my wholesale suppliers. Sometimes significantly less -
but being "grey market" there is no support and often no accessible
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