A friend has a house in the mountains. No A.C. The furnace is as old as
the house, probably 1965 or 1970. Are new furnaces more efficient in their
use of natural gas, and thus "pay for themselves"? If so, how does one
calculate the anticipated savings and pay back period?
New high efficiency furnaces are as high as 98%. Regardless cost, up
here in Canada lagally low to mid efficiency furnace can't be installed
on new install. Think your friend's furnace is not even mid
efficiency(80%) being that old.
I just had my new one put in yesterday and it is 96% efficient
I expect that compared to the 80% furnace it replaced and the high
Wisconsin heating bills it should pay for itself in well under 10 years.
98% ones are high maintenance item. I installed 96% one too, So far no
problem since day one. Matching A/C unit has been running same. Last
year I hat it checked for topping up the Puron but tech. told me, don't
need to. He evacuated, weighed it and put it back.
On Tuesday, January 27, 2015 at 8:48:57 PM UTC-5, Tony Hwang wrote:
What exactly makes a 98% one high maintenance as opposed to 94, 95, or
your 96%. I would think the essential difference would be that the
higher efficiency would use a slightly more efficient and costly
If you don't mind, which brand did you buy, and what was the approximate
I've got a 1988 Burnham gas furnace in my 1911-vintage and very leaky
1400 sq.ft. house. Last month's bill indicated 224x100 cubic feet of
It's still running fine, but wondering if a more efficient furnace would
make much of a difference.
A 1998 furnace is probably not more than 85% or so but I'd have it
checked to be sure.
You may get a better return stopping some of the leaks though. It can
get expensive replacing doors and windows, but covering existing
windows, insulating, and spray foam have a quick payback.
Older furnaces can be from 50% to 70% efficient while newer ones are
over 90%. If you replace a 70% with a 98% you save roughly 28% of your
A few years ago I replaced my boiler and save nearly 40% on fuel costs
and it is enough to pay for the cost over about 7 years. There may be
rebates available or special financing so be sure to check it out.
On Tue, 27 Jan 2015 14:45:26 -0800 (PST), email@example.com wrote:
I know more about oil than gas.
When I divide the output BTU's*** by the input BTU's on my 1979 Carreir
oil furnace (hot air), I get about 80%. ***As listed in the owner's
manual that came with the furnace, and is online too.
When I was shopping for a new furnace a couple years ago, the efficiency
of all of them** was about 82%. (iirc but at any rate, little higher
than my furnace rating.)
People here at the time did not believe me that the efficiency has gone
up so little.
Are you somehow giving the measured efficiency or the rated one?
Anyone know if there is an innate difference in the efficiency of hot
air furnace vs. a hot water furnace?
** (except some special kind that is very expensive, not so often
advertised or even mentioned, and very few buy (whose design name I
forget. Retroactive, incandescent, self-descending, or something.).)
Doesn't confuse me. Most "boilers" in residential heating don't come
very close to boiling.
But to answer the question, since they are producing 95% "efficient"
boilers for residential use, I'd say they're probably more efficient
since a circ pump probably uses less electricity than a blower.
It's not a choice for most people if they like central A/C , because
it's generally forced air heat that provides the vents for it.
As far as I know new houses are overwhelming equipped with force air
My house was built in '59 or '60 and came with forced air.
It was simple for me to add central A/C when I replaced the furnace.
I don't see how that's possible, unless an extra ambient air heat exchanger
is used. I never measured a system. If incoming water is heated by another
pre exchanger with output of main exchanger, the flue gas will be closer to
incoming water temp.
In this thread, an oil-fueled device that heats water as does the " 2001
Burnham V8(oil burner hot water)" that thekmanrocks says he has
Sorry, I don't know what hydronic means and it's not a word the poster I
was replying to used. .
Of course. I was just trying to figure out if there was a reason other
than the choice of fuel, oil vs. gas, and the device used to burn it,
that might account for his getting only 80% now. I didn't want to
emphasize the 80% that my oil furnace is supposed to get heating air if
a more recent oil burner would get higher than 82% efficiency when
heating water. Although now I'm no longer sure the
ratings include heating either air or water. They may ?? just include
any heat that doesn't go up the chimney or other vent, and if there is
some lack of efficiency transferring that heat either to the air or the
water, that would be a) another problem, and b) one that manrocks can do
nothing about unless he plans to remove the radiators and replace them
with air ducts. (And that's only if hot air is more efficient than
water, and not the other way around.)
Of course, both setups sort of lose heat in transmission to the rooms,
but the heat is lost within the house, inside the walls or the utility
shaft and isn't really lost at all, afaik. The warm walls or air
outside the living space slow the cooling of the living space warm when
the furnace is not running. .
What might be a good idea is to put heat reflectors behind the
radiators. ??? When I slept right next to a steam radiator, either we
had enough heat or no heat, so it wouldn't have helped.
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