Maybe Turtle or one of the HVAC guys will give you a pro's opinion.
I would guess that a 1962 furnace started out at 55-60% efficiency. May not
be working that well now.
Modern bottom of the lines get 80%. You can buy 92+%.
So with an 80% model I would figure a 20% savings. You might get more but
this is conservative.
Now if you have central air those numbers will really blow you away. You can
expect up to 100+% improvement in operating cost over a 1962 model.
If your old furnace is 60% efficiant, 40 cents of every dollar you spend on
gas goes up the chimney. If your new furnace is 95% efficant 5 cents of
every dollar goes out the vent. You will save 35 cents of every dollar you
If you spend $500 a winter for fuel, you will save $175 for the winter.
$1000 a winter for fuel, you save $350.
$2000 a winter for fuel, you save $700.
If you live in the snow belt it probably would be worth changing out.
If you live in the south, it will never pay off!
Insulation and weather stripping is a better deal yet. Make sure you have
your house tight as resonable.
Do the math.
Assume the old furnace is 55% efficient.
If you go to a new 80% efficient, the new furnace will use .55/.80 = .69
of the fuel required by the old one, i.e., you save 31% on the fuel.
If you go to a new 92% efficient, the new will use .55/.92 = .60 of the
fuel required by the old one, i.e., you save 40% on the fuel.
If your gas bill is like mine, in addition to charges for the fuel,
there are flat delivery fees, etc. so that the OVERALL percent savings
on your gas bill will not be as great as the percent savings on the fuel
Additionally, consider the maintenance/repair charges for the old vs.
the new furnace -- some of the new furnaces have VERY expensive parts.
I know. I have a vintage 1980 gas furnace. I can maybe save 30% of
the fuel portion of my gas bill during the winter. Doing that math at
last year's prices that's about ~$110-$125/year in savings! Like I'm
going to spend $3000 for that. Even if you do get a new furnace I'd go
with the more fixable 80% model or get a heat pump if you have cheap
electricity like a lot of places where most is generated by nuclear or
Please tell me why the 80% model is more fixable?
I hear this all the time from clients, and would like to know rather you
actual know the difference or are just speculating.
But, I'll tell the OP what I tell my clients about what the other tech told
them, here it is....
They are full of SHIT!!
Same reason a Chevy Cavalier is cheaper to fix than a Cadillac.
The 80% does NOT have a sealed combustion chamber (90+) do.
(this can be a good thing though)
Did you ever look at the complextiy of a 90+ unit, more sensors,
and more things can fail. Gee whats the price difference between
a variable speed motor and a standard one??? What about the
components to handle that motor. Its not a basic relay I can
tell you that!
I personally would recommend the 80% two stage units. Fairly
straight forward with the flexibility of a high heat rate to get
the house up to temp.
Wrong, some 80% models do have sealed combustion.
Complete <cough> BULLSHIT!!
NO more sensors, No more complex controls, in FACT...the same number of
controls and ALL of the major controls are the EXACT same part!
You need to either get oout more and learn something about the trade you're
in or talk about the other trade you're in, cause from your post you are not
a competent HVAC tech or owner!
Who said anything about the blower differences? I didn't, you do realize
that you can get both models with or woth-out variable speed blower motors,
Here again, nobody said anything about the variable speed blower, we are
talking about efficiency differences.
Personally, I would perfer for people to keep there computers off if they
are going to talk out there ass about something they know nothing about!
As far as furnaces go, it all depends on the area you live and rather the
payback is there to warrant the better equipment.
As usual, someone says 'high efficiency and everybody starts screaming...'to
hard to fix', 'more problems'...well if you can't fix the 90+, you can't fix
the 80+ either.
Heat can go into the house, or up the chimney. Check the flue pipe coming
out the top when the furnace is running. Is it very hot? Well, that heat
could be going into your house instead of heating the birds on the top of
The new furnaces also use less electricity. They make stuff lighter now
I don't have any numbers, but that's how you can get a feel for the matter.
It depends what you're installing as replacement.
Old one is very low efficiency for sure(30-40% at most?) latest
high efficiency furnace has way more than double that figure. And there
is mid-efficiency ones at around 75%. Do your math.
I don't care what kind of furnace you get - if you don't teach it the
value of money, as well as wise spending habits (i.e. - is this a
"want", or a "need") - it's very unlikely your furnace will save any
money at all.
I'd open a savings account for your furnace. It helps it to
conceptualize hwo to save money.
'I'm looking at replacing my gas furnace this coming summer. It is an
original installation, 1962 vintage. What percentage energy savings can
I reasonably expect to see?
Your present furnace is most likely operating in the range of 50-55% if
its been regularly maintained ; not only will you see very good
savings in gas ,but, you will find an increase in air volume due to the
beefier blower assemblys that come in modern furnaces. Have contractors
perform a detailed Heating Load Estimate on your home so your
replacement furnace is accurately sized. I personally prefer the 90 plus
/ 2 stage gas furnaces .
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