On Feb 2, 9:16 pm, email@example.com wrote:
Show us any furnace that is sold as an 80%+ furnace that reaches
98% efficiency. Or 95%, or 93%, or 90% in a data sheet spec.
Or a data sheet showing that an 80% furnace reaches 85%.
Whatever that 80% furnace is reaching, it's still pretty close to 80%
and nowhere near the efficiency of a 95% furnace that costs $200
Furnaces of various types, including 80% are marketed
as 80%+ because some models within that product line are capable
of SLIGHTLY higher output when tested according to DOE
procedures. So what? You apparently think that because you
bought an 80%+ furnace, that "+" somehow makes it unique among
furnaces, a marvel of science that defies physics and gets some
significantly greater efficiency than 80%. Let's say it gets 82.6%/
Use 82.6% instead of 95% and it doesn't materially change the
I can do both. But you can't even keep straight what you posted:
"And the 80+% efficient furnace is supposedly
running about 85% as installed - "
"He didn't say that, and nor did I. I said it is an 80+ % efficient
furnace, which he stated is likely running closer to 85% than 80% "
So is it 85% or just 82.6%, or just some mumble jumble
crap spouted by some numb nuts guy trying to sell a furnace.
You're incapable of realizing that this point, which you keep bringing
up, just makes your case worse. With a draft inducer in the 80%
furnace, the only difference left between the 80% and the 95%
is the second heat exchanger and $200 in cost.
A - 80%, two stage, ECM blower
B - 95%, two stage, ECM blower, $200 more
I stand by my earlier statement that only a moron would go out and
buy choice A. That's purely from a dollar and sense standpoint.
I'd also consider that with the concern about CO2 emissions, it's
always a good thing today to go with the choice that's going to
emit less CO2, where it's possible and doesn't have a significant
And I quickly corrected my error on the draft inducer point.
Unlike you, who frequently puts out total
nonsense and then won't even correct it. Want an example? In
another thread here, a couple days ago, you questioned when the
last time anyone saw a car battery with removable vent caps,
implying they don't exist anymore. I have two of them sitting in
my cars in the garage. Another poster responded similarly. Did
you admit you were wrong? Of course not.
Or how about when you claimed modern cars don't have dozens
of microprocessors, because when those microprocessors are
programmed to one or a few functions, function, eg radio control,
or air bag control, they magically are no longer microprocessors?
I'll leave it for others to judge who the village idiot is here.
The data from your old furnace company is not necessarily universal. I
have the receipt from the Chysler Air-Temp that was installed in my
house in 1973, before I purchased the house. It is for a 100,000 btu
I removed that furnace many years ago, but the rating plate read,
100,000 input, 60,000 btu maximum bonnet capacity.
I replaced it with an 80%, 75,000 btu furnace (same 60,000 btu output)
and it easily matches the old unit.
So that is a 1970s furnace with the standard rating system.
Well this is very enlightening (and confusing at the same time). I
should have mentioned that mine is a Carrier, who I didnt' think was
some beatnik hippie namby-pamby non-conformist outfit.
I guess the next logical step is to go look at Carrier now and see how
they label their furnaces. Or maybe to email Carrier or ask on
Maybe I shoudln't have but I called Carrier, and the very nice girl on
the other end was so sweet and helpful and I thought I explained the
question well, and after a minute or two she came back and was going
to send me the manual for the furnace I have now.
I asked her if that was still the system they used for picking model
numbers and she said yes, off the top of her head, without further
research, and I don't trust her anymore. I sort of knew the question
was too hard for someone who doesn't actually deal with real models
and real outputs.
Rather than my 3 ideas above, I'll have to hunt for some Carrier oil
furnaces online and compare model numbers, ratings, input and output.
I should have thought f
I had to hunt quite a bit. A lot of the pdf documents said nothing
about btus, but I finally found one.
They have changed afaict. Carrier now rates oil furnaces on "Input
And they call the output Heating Capacity.
The first 5 characters of the full model number are the model.
The next 3 numbers are input capacity, and with a multi-nozzle,
multi-usage model (many, most or all of them are like that now, not
just carrier) the 3 numbers are the highest input used.
So the Carrier girl was sweet, but I think she was wrong.
Okay, that might be it.
I had a couple questions and I called the ebay seller and he said he
was looking at the manual and the 85,000 was output, but I can find
out by checking out the model online. It's too cold and snowy to go
buy a furnace today anyhow. And I've been up since 4:30.
The time to install a furnce is mid spring.NOT MIDDLE OF WINTER:(
They make multi input furnaces which increase efficency.
They run at say 65% of rated output, and if its not too cold thats
fine and the furnace turns off.
But if its super cold the furnace continues to run and the unit
inceases it btu output.
this for zero weather. Its a more expensive and complicated furnace
but gains a few % efficency.
You have to remember most furnace installers put in LOTS of furnaces.
If your home is a tract home they go with what worked the last 100
Why waste time doing a heat loss calculation if you already know the
I'd like to see a credible reference that says a two stage furnace
gains a few % in efficiency running at the lower stage, instead of
the higher. If that were so easily possible, then they could achieve
similar gains with any furnace, by just resizing the burner relative
to the rest of the unit. And in the game to increase efficiency in
general, you'd think that would be happening, no?
All the gas furnaces I looked at for specs made no distinction in
efficiency between the two firing rates. I would agree that there
could be some small difference, but I'm betting it's so small that
it's close to neglible. Offsetting that is the increased upfront
cost of the two stage furnace, additional service complexity,
more parts to potentially fail, etc.
Two stages used to be sold more on comfort issues. On moderate
temp days, they can run longer, providing more air flow through
the house, evening out temp differentials, eliminating hot spots
near registers, etc. Somewhere
along the way it got morphed into efficiency, and I had contractors
standing here telling me that it's gonna save me a lot of money,
which I think is pure BS.
It think that's exactly what's going on. They wing it based on
with similar homes and alwasy err on the side of it being a bit too
instead of too small. How many customers are ever gonna call up and
bitch if their furnace runs only 1/3 the time on the coldest days?
it can't keep the house at 70, you can be sure there's gonna be
On Jan 28, 8:43 am, firstname.lastname@example.org wrote:
I agree, 2 stage is more a comfort feature than a savings feature.
Any differences in total operating cost to keep the house warm will be
miniscule. If you don't have a comfort issue with an existing single
stage unit then there is not a lot of reason to go two stage. I also
agree on the thermostat, if you do two stage then get the two stage
thermostat. Stupid not to.
On Fri, 28 Jan 2011 06:39:22 -0800 (PST), jamesgangnc
which I do not.
Everyone is talking about more complexity being a bad thing, more
expensive, more trouble prone, more difficult/expensive to repair, yet
in the same breath they say I'm "stupid" not to have the more complex
Fine for new construction. But if I have an existing furnace of a
efficiency and know what percent of the time it's running on the
days of the year and how long it takes to raise the house temp during
a recovery period, I say that is at least as good as the theoretical
A calculation BTW, which NONE of the 5 reputable contractors I got
quotes from did. Nor did mm.
Well, I called the seller and he told me that the 85,000 referred to
output, but because he's the seller, I doubted him. So I looked for
Thermo-pride online and I found the manual online and indeed, Model
oh5-85 has 85,000 Heating Capacity in BTU/hour. Model
oh11-105 has 101,000 Heating Capacity in BTU/hour, but 101 is a lot
closer to 105 than the input rate which is 126,000.
In the meantime, Carrier which used to echo the output value in the
model number has changed to including the input value!
Very confusing and indeed a possible source for buying the wrong
None of the guys who gave me estimates sent me written estimates that
named the model they intended to install. :)
You should ask for the equipment to be listed. Otherwise you have no
way to compare estimates. Normally they will provide an equipment
list with the estimate. Some wil give you a couple estimates for each
of the brands they normally install.
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