You've admitted that furnace life-spans are getting shorter today vs
Isin't that proof? Isin't that an example of how they are coming down
to match (but never fall below) the average length of home ownership?
If in 5 years we observe that the lifespan of the average new furnace
is 7 years, does it matter if we call that a "goal" ?
Any old furnace that's 25+ years old can have it's efficiency raised
easily by 10 to 20% simply by turning down the burners. The design
goal for those old furnaces was to blast out the heat in those
un-insulated homes. They had no concept of constant heat. They had
crappy mechanical thermostats and couldn't achieve constant
(comfortable) heat output.
Now those homes have added insulation, and if you turn down the
burners so the furnace runs longer (but cooler) you've just raised
their efficiency and probably increased their lifespan too. Adjust
the burner primary air baffles too so that you're not blasting the
flames straight through to the flue (ie - increase flame residency
time within the heat exchanger to extract more heat from the flames ->
slow the flames down).
And I think it's a crock that your only choice is to replace a
45-year-old furnace with one with an expected lifespan of 20 years. I
don't give a damn about how much fuel savings there will be. There is
no logical reason why lifespan needs to go down when efficiency goes
Back in 1955, what was the inflation-adusted price of a furnace?
Were people paying a fortune back then for furnaces?
Are furnaces today less expensive (in real dollars) compared to 10,
20, 30, 40 years ago?
What good is it if you pay less for a furnace today vs 30 years ago,
but you have to buy it twice as often?
You're telling me it's a good thing for the environment to have to buy
a furnace every 20 years vs every 40 years? Do you know how many more
households there are now, compared to 40 years ago?
We have 95% efficient furnaces today. You're saying it's a bad thing
if they last 45 years - because we want people to replace them more
often. So I suppose we want them to last only 20 years - because 20
years from now we'll have a 98% efficiency? So for the sake of a few
extra percent we want people to buy new furnaces? What the hell kind
of logic is that?
Who are you?
A home owner?
Or an HVAC reseller/installer?
If the energy-saving argument is correct, reliable, proven or
garanteed, then I don't have to wait for my 45 or 30 or 20 year old
furnace to break down. I can choose to replace my furnace at my
conveinence. Or not.
Saying that it's a good thing that furnaces last only 20 or 25 years
is a crock. If that's what you rely on to make the case to buy a new
furnace, then that's a bullshit argument.
Do you know how many old fixtures, tiles, railings, etc, are being
torn out of old homes to be installed in new or renovated homes?
Don't confuse style with function. Those old fixtures went out of
style 30 years ago, but they still function, and now they're back in
Many people do.
I've got a news bulletin for you.
You don't need a furnace full of electronics, sensors and computers to
get 95% efficiency. We have 95% efficiency because we have more heat
exchangers, essentially more "plumbing" inside furnaces. Closed
combustion, intake air pre-heating, etc. Not even electronic ignition
is needed (that is another gimic that saves very little energy, and
certainly saves no energy when the burners are running).
Of course they knew what it took 50 years ago to build a 95% efficient
furnace. There just was no demand for it.
We're not talking about AC. That's another matter.
And if you want to know how "plumbing" can help even more - I'll tell
Ductwork should be gated such that in the winter, air can flow around
the A-frame instead of being forced through it. And in the summer,
air should be ducted so it doesn't have to flow through the furnace
Take those resistances out of the picture and you've just raised the
efficiency of the system. No fancy electronics required.
And you've got no comment about this eh?
| In Japan, they have furnaces with built-in 1 kw electric
| generators to provide some electrical co-generation that
| can supplement the electricity supply for the house - and
| keep the blower running in the case of complete power
| outages (like what's happening to thousands in the central
| USA right now).
The biggest crock of shit about furnaces today is that they can't
generate their own electricity to run their friggin internal mainframe
computer - and their blower motor during a power outage. I bet the
electronics in today's furnaces consumes more electricity than the ECM
fan motor does.
In a word, no. That's like saying because the average power tool one
buys today lasts
for a shorter time, the goal of all the power tool manufacturer's is
to reduce the lifetime
of their power tool products to two weeks worth of use.
In other words, yes, I agree a furnace doesn't last as long today.
But that is a reaction
to market forces, ie what customers want and what they are willing to
pay, just as it
has always been. There is no master plan to reduce furnace life to 7
Yes, it does. Because you claimed it was an intentional plan by all
to do exactly that and I see no proof of it.
I'd like to see you take any old 45+ year old furnace and make it 95%
I would wager that just like most other things, the answer to your
question is yes.
I'll bet if you look at what a furnace 40 years ago cost and adjusted
you're getting a new far more efficient, lighter, easier to install
furnace today for
a whole lot less.
Well for starters, if it cost about 1/2 as much you'd be way ahead.
And that's because
you wouldn't have to shell out the extra money decades ago for a
product that cost more
so that it would last 40 years. Plus, it's obvious today's furnaces
are far more efficient
so you're going to save on fuel. Plus, they have new convenience
features, like a variable
speed motor. Didn't this thread start because the OP wanted to save
energy by trying
to retrofit an ECM motor into an old furnace? If he paid a
reasonable price for the furnace
and it's near the end of it's life, then he can buy a whole new more
efficient furnace that
includes that feature. He could even consider switching fuels, maybe
going to a heat pump,
etc, depending on his location.
That's what customers want. Say a new HVAC system costs $6K and lasts
That works out to a whopping $300 a year. Consumers are spending way
more than that
for energy. Way more than that for all kinds of entertainment
items. So, spending that
per year for a HVAC system, seems very reasonable to me. And of
course if you limit
it to only a furnace, it's even less.
That's what manufacturers are reacting to and building for.
Yes, I think it is and as I pointed out, environmentalists, govts, and
Which is why they offer rebates to encourage people to replace old
furnaces with new ones.
Again, you focus on the energy used to make the furnace, but
the bigger amount of energy used to run an old inefficient one.
I'd like to see one credible referrence to anyone that agrees it's
better for the envrionment
to continue to use a 40 year old furnace or HVAC system instead of a
No, I'm saying if a manufacturer built such an HVAC system today, it
so much that few customers would want to buy it. Manufacturer's for
most part, aren't stupid. If they saw a market segment opportunity
a product, they would offer it.
So I suppose we want them to last only 20 years - because 20
I'm saying if you look at the cost/benefit and value proposition,
around 20-25 years
is the sweet spot. It means customers don't have to shell out extra
and that in 20 years, the furnace is depreciated and they can look at
alternatives are available then. Are you clairvoyant enough to know
that in 20 years
the same fuel will be the best choice? By then, the energy
situation could be entirely
different and then maybe a different system would be better instead of
being locked into
a more expensive system that lasts 40 years.
A homeowner. A homeowner with a 23 year old HVAC system that is
nearing the end of
it's life. It doesn't owe me a thing. And I'll be happy replacing
it with a new, more efficient
system that lasts about as long.
That ignores the fact that it's going to cost significantly more for a
old system upfront. Factor in paying more upfront and the time
of money over 20 years, ie interest that could be earned, and the 40
furnace is what's a crock.
Do you know how many HVAC systems are being torn out of old homes
and being installed in new ones? Zero.
Do they take some special old fixtures out of some old homes for
Sure. What percent of times does this happen? So small it's not
talking about as applied to the broad market.
I've been through dozens of new construction homes in the last year.
yet to see one with a 40 year old toilet, rail, or anything else.
happens in some cases, but it's a niche market. In fact, if you want
style, most people looking for that old look style typically buy a new
version of that
product, ie they go down to the plumbing supply and buy a new claw
That doesn;t answer the simple question of whether 95% efficient
were available 50 years ago. And you missed the elephant in the room.
For whatever reason, that 50 year old furnace is no where near the
of one you can buy today. So, what;s your point?
No, it isn;t. Because today most people have both as part of one
Are you telling us that it's also economically sound to run a 30 year
AC system that was bolted onto a 50 year old furnace instead of simply
getting a new system? Or that one should just replace a failed 30
old AC system on an even older furnace? LOL
But again it shows why 20-25 years is the sweet spot in terms of
Yes, I do. If you're so smart and know the technology and market
so well, why don't you go get venture capital, start a company and
products designed to last 50 years. I'll bet the system will look a
lot like the car Homer Simpson
designed for his brother's car company and have similar success.
On Dec 23, 9:10 am, firstname.lastname@example.org wrote:
Ive been told new furnaces heat exchangers are thinner to transfer
more heat and be more efficent, an old unit I took out weighed alot
more but was real inneficent. Stainless Steel exchangers with a long
warranty maybe 20 years are offered by a few.
Unless I add a second heat exchanger, no, it's not going to reach
95%. But there's no reason it can't reach 78% efficiency. Without
adding computer controls and electronic sensors.
If "most other things" are cheaper today (in real dollars) then that
must mean we're all richer today vs years ago.
I suspect that most other "important" things are not cheaper today.
Well, I welcome some hard numbers here otherwise this is just
It is not environmentally sound for me to buy a new 95% efficient
furnace that lasts maybe 15 or 20 years (instead of 30 or 35 years)
and replace it with ANOTHER 95% efficient furnace.
What if that 40-year-old furnace is a 90+ furnace?
What if it's an 80% furnace?
It's a no-brainer that natural gas will always be more economical vs
the only real alternative (which is electric heating).
And if we run out of natural gas in 30 or 40 or 50 years, then welcome
to the world of Mad Max and the end of civilization.
Like I already said, they could have made condensing furnaces 50 years
ago. I bet some were available for special situations.
I already made my point.
It doesn't take computers and electronic sensors to make a 90+
condensing furnace. It takes more heat exchangers and more "plumbing"
(ducting, etc) inside the furnace. More sealing, a closed combustion
loop, and more work at the job site to install and plumb (duct) it all
Back when natural gas was cheap, of course the industry and customers
are going to ask why build a more complicated (expensive) furnace when
the fuel is so cheap? Instead they built long-lasting, durable
It doesn't matter if the evap coil is built into a furnace or if it's
installed in the plenum above it. The AC unit is a completely
separate system that just happens to share the same ducting and blower
as the furnace. And as I've stated, it's actually inefficient to
combine the two without gating because it does add resistance to air
The economics of the furnace or the AC unit has got nothing to do with
one being "bolted" to the other.
If the furnace is 50 years old and if the AC unit is 30 years old then
you look at those units separately when analyzing their cost of
operation. The fact that they're "bolted" to each other doesn't
matter - the "bolting together" doesn't affect their relative
efficiencies or costs of operation.
I don't have the same hang-up that you do where you see the furnace
and the AC unit as inseparable.
As has been pointed out several times in this thread, current 90+
furnaces are struggling to achieve 15 years of service life.
I can totally understand that the average american is so strung-out
(money-wise) that hvac makers are responding by making units that
barely hang together and that builders are putting crap like that into
But what I can't understand (if this is the case) that all hvac makers
have changed ALL of their model lines such that they no longer offer
units that absolutely will last 30 - 40 years (and then charge
accordingly for them).
Changing your ductwork as I described above is not related to changing
the longevity of the HVAC system.
The AC evap coil (A-frame) is an unneeded resistance for the furnace.
Would you like to argue otherwise?
I don't know if you've noticed, but most HVAC installations don't look
pretty when all their various lines, connections, and ducting is
This type motor is known for failure mode for motor and controller going
out together. Most people who has this thing in their furnace, they take
out 10 year warranty for that part. If you buy and use it as constant
speed blower at an expense, that is fine for the purpose of experiment
but economy wise I don't think you'll recover initial cost and if it
In a previous post, I've already roughly calculated that I'd probably
save $40, possibly $60 per year if I changed my PSC motor for an ECM
The question that I continue to ask is: What is the
"over-the-counter" price of an ECM motor?
I can walk into any hardware or farm supply store and buy a 120v, 1/3
hp PSC motor (for $75 to $150).
Where do go when I want to pick up an ECM motor?
Who sells them "over the counter" ?
Lennox is known for selling parts only to trade people. You can contact
other brand supply house or try on-line search. Another issue maybe
mechanically fitting it into your existing set up. Prepare to pay
over a grand for motor and controller. How much is electricity cost
where you are? I have locked in rate of 7 cents per KWH for next 5 years.
That sounds like a crock of shit. I guess the HVAC industry is full
of companies that limit the availability of parts to the general
public. Stone-age thinking these days.
I agree, but that's my problem (if I go down that road).
Again the controller issue. Has anyone ever seen a data sheet for
Has anyone considered that the controller is built into these motors,
and maybe they have just a few control lines for speed selection -
that can easily be rigged up for manual control (or set to run at a
constant speed) ???
While on that topic - are there any electronic thermostats that can
control multi-speed motors?
I pay 10.6 cents per KWH. That includes ALL direct and indirect
costs. Indirect costs include taxes, delivery charges, regulatory
charges, etc. The electricity itself is billed at about 5.8 cents per
When my meter is read, the reading is multiplied by 1.0421 (some sort
of correction factor for line losses I guess).
Does your cost of 7 cents include ALL miscellaneous charges and taxes?
The above two are more like sales sheets or flyers, not really data
sheets with pinouts and wiring diagrams.
But still, they confirm that the controllers are built into the
motors, and they can either be set to run at constant speed, or
constant air flow (not sure how exactly they can sense airflow), or
they can take a control voltage (2-10V) which is trivial to set up
next to a thermostat.
If I had one of those, I'd tinker with it to see if I could get it to
run off a DC supply. A DC battery backup would keep a motor like this
running during winter power failures. I bet there are some in the
plains and mid-west who know all about winter power failures.
"Most variable speed electronic devices, including the ECM
operate with a rectified and filtered AC power. As a
result of the power conditioning, the input current draw
is not sinusoidal; rather, the current is drawn in pulses
at the peaks of the AC voltage. This pulsating current
includes high frequency components called harmonics."
So these motors are likely to radiate RF/EM noise if filtering isin't
used (and given manufacturing price pressure I wouldn't count on these
having proper filtering).
And one more thing - the power utilities really like these non-linear
loads - NOT!
Someone trademarked "ECM" ? Are you kidding?
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