On Wednesday, January 28, 2015 at 6:15:11 AM UTC-5, philo wrote:
Similar here with my 93% Rheem. There isn't anything exotic there
that I can't fix myself.
That helps too, same here.
I got the fed tax credit back in 2010, which was ~$1200. Those
credits reduce the cost substantially and there isn't but a few
hundred dollars difference in the cost of a 93% furnace compared to
an 80% one.
My 16 year old furnace gets an annual cleaning and inspection as part of
an annual maintenance agreement, for less that $250 a year, that has
saved me many dollars on several occasions when parts went sideways.
The system will be down for 10 days for preventive maintenance.
On Tuesday, January 27, 2015 at 6:07:34 PM UTC-5, Curmudgeon wrote:
I'd be happy to see data that supports that. There are a lot of people
with fuel bills of $1500 a year. If they save 20%, that's $300 a year.
In ten years, it's $3000, about 50% more than the cost of the furnace
equipment to begin with. I replaced my 27 year old nat gas furnace
4 years ago and have been saving 40%+, Ed reports similar with a boiler.
I'm saving about $300 a year. The most costly repair, would be the
heat exchanger. All the systems I looked at, the heat exchanger was
either warranted for 20 years, lifetime, etc. Not saying you won't
have to put some money into an aging furnace, or that a high efficiency
one doesn't have more parts that can fail, just that I haven't seen
any real data to support that it's going to wipe out staying with a lower efficiency furnace.
Yes, there are more safety devices on modern high efficiency furnaces,
so there is more possibility of one failing. But I also wonder how
many safety switches there are on a new 80% furnace now too? I've
got 4 years now with a Rheem 93% furnace, not a single problem.
This year was another $610 for a draft inducer.
If she paid $610 to have a draft inducer installed, I'd say the
more likely problem is that she has a service company that is
screwing her. I'd also point out that a lot of stuff today doesn't
last as long as it used to. I think in many cases folks are comparing
the lifecycles of 40 year old furnaces to modern ones. I'd be
surprised if a new 80% furnace lasted as long as one did bought in
1970 too. In other words, you have to compare the problem rate of
a new 80% with a new 93%+.
On 1/28/2015 8:53 AM, trader_4 wrote:
s after the furnace is 10 years old or so.
I was skeptical when the advertising said you can save up to 40% on fuel
use. I figured if I save 25% to 30%, I'd be happy I kew what my oil
consumption was the the past couple of years so I had numbers for
After the first year, I calculated the oil use based on degree days. At
www.degreedays.net I was able to get the historic data also. I was
pleasantly surprised to see that I came very close to the 40%. I even
contacted Energy Kinetics, makers of the System 2000 boilers. They did
their own audit and concluded I save 39.2%.
In my case, the old boiler was about 30 years old and on the way out
soon so I had to do something. It was also good timing with Federal
energy credits, state rebate and state 0% financing. It would have been
foolish to do nothing and pour money up the flue.
So far, it has been trouble free, no repairs. Once last winter I had to
cut the power, let it restart and it has been OK since.
our experience was that within 12 years the heat-exchanger
went and even while the company did replace it we still had
to spend quite a bit of money to do that. we also had a lot
of problems from the ignition system. whatever part it was
they were getting was coming from Mexico and it failed each
year. finally we asked them to find something else and it
hasn't been any trouble since.
our heat costs run between $600-1200/yr on propane (normally
the thermostat is set at 58-60F). i think our unit is rated
at 95% or so. 98% would have cost us about $500 more when we
replaced the exchanger. we've also had to replace the fan.
i sure wish this place had been set up for more passive
solar as right now this mid-winter cold day the sun is shining
nicely and we could be avoiding some of the expense of heating
(for hot water too).
I put in a coleman THE about 25 years ago and the efficiency was 90%.
This unit was inexpensive (actually designed for a housetrailer, but it
was big enough for our house). I think the trick was they passed much
more air through the heat exchanger. It needed no chimney, but the air
coming out of the registers actually felt cool, but there was so much of
it that it heated the house. My feeling is that you can compare
efficiencies, but you cannot calculate payback periods because gas
prices vary and weather varies. All you can do is keep track of your
costs and calculate payback period retroactively. Anyway, because of
abnormal weather and changes in gas prices, that unit paid me back in
just over one year. I don't expect to ever match that performance
again. It had some design problems and after many years, I was seeing
the repairman too much. So this year I replaced it with a Bryant said
to be 95.5 efficient. The biggest change I noticed is that it has air
from outside the house pumped in and used for combustion. As a
consequence, we don't have outside air in the house, and the air coming
out of the registers is much warmer. It also has a high efficiency
multi-speed blower which comes on at a lower speed during some of the
furnace's idle time to circulate the warm air in the house. I haven't
had it long enough to calculate how much, if any, it will save us, but
the increased comfort is worth a lot. Now I'm looking at adding a heat
exchanger to get some fresh air into the house
Unless you change something else drastically, the Btu demand to heat the
house will be the same so two units of different efficiencies will
produce those total Btus with the relative amounts of fuel that their
relative efficiencies indicate to within a (quite) reasonable approximation.
Hence, one can do a reasonable estimation of payback period knowing past
history and costs. One can't know precisely what a given winter is
going to bring, granted, but that's not of real concern in getting
Now, if one changes the parameters by also adding/upgrading insulation
or increasing the footprint of the house by adding in previously
unheated/marginally-heated areas or is switching from a boiler/steam
radiator to forced air, then, sure; there's enough difference as to make
the computation much more difficult and certainly less accurate.
But, presuming from the question as posed that this is simply a drop-in
replacement/upgrade request, I'd say he'd get a pretty good estimate
simply by ratio of the proposed unit efficiency to the existing. Now,
getting a reliable number for the current unit may be the biggest
uncertainty altho 50-60% is probably good enough for the purpose.
I've not priced recently, but when we upgraded/replaced here about
three/four years ago now, the price differential between the ~95% and
the higher units started to really escalate. Same as with the SEER
ratings on the AC side. The payback can get really long if one goes to
the extreme. We ended up w/ a 95% Carrier and while I've not compared,
the difference is notable. Of course, NG prices have peaked and dropped
at least a couple times over that time period, too...
Think of it this way. On a 80% efficient furnace, 20 cents of every
dollar is wasted. On a 95% efficient furnace, 5 cents of every dollar
is wasted. Have your friend figure out what the savings would be by
their fuel bill.
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