How many fans does one air conditioner equal - energywise?
Joe
conditioner that is not on. It would cool down a good portion of my
house better than the 6 fans to the point that I could turn off my 6
fans. Is it possible that my 6 fans are using more energy together
than my one air conditioner would? Has anyone done the math on this?
Rick
To get a technically correct answer you'd have to track down all that
wattage/amperage info from all the items, add it up, and cross compare
it.
On a less technical level, I was surprised to find that last year there
was no significant change in my electric bill between the month where I
was running 4 or 5 fans all the time vs. breaking down and finally
running the two 5200-5500 btu air conditioners once the humidity levels
went unbearable. Of note is that both my AC unit were brand new last
season and have high energy efficiency ratings. YMMV depending on how
old and inefficient that 11000 btu unit is.
Rick
Michael Black
The fans aren't so much about making things cold, they are about
circulating the air. Admittedly I'm not in extremely hot climate,
but I find that I can plug in that muffin fan (out of a computer
power supply) that I've hooked up to an AC adaptor that I found
in the garbage, and the air from that can make a dramatic
difference. It has the advantage that it's not blowing hard,
which I find I dislike about regular "fans".
You have to decide. Are you trying to keep cold, or trying
to save energy? Because anyone trying to save energy or money
would be making decisions about how much heat they can tolerate
before they need to start spending a lot of money on cooling,
rather than "what's the most effective".
You can also do things like close blinds on windows that are in
direct sunlight, otherwise you start getting a solar cooker going
and heating the house like that is the complete opposite of
cooling things down.
Michael
Dave
"Joe" <joe...@gmail.com> wrote in message
news:1183999637.3...@k79g2000hse.googlegroups.com...
Wrong question. It's not the heat that makes you uncomfortable...it is
humidity. Fans won't help a bit if the humidity level is too high. The
fans just circulate HUMID air.
Fans should be used in addition to air conditioners (if necessary), not to
replace them. -Dave
Rick
But that wasn't really the question at all. The OP is looking for a
frugal justification for running the AC versus running a whole bunch of
fans. They weren't asking what option would make them more comfortable,
just which one is more cost effective.
Going to your point though, if the AC is a new model - preferably one
that is up to current energy star specifications - it may cost no more
to run the AC and be comfortable than to keep 6 fans going and still
feel like you are living in a swamp. The only real way I know to check
it is to find out the electrical usage ratings on the items in question
and compare them. Or do it the lazy way like I did - run the AC instead
of the whole pile of fans and see what happens to your electric bill.
Since we're talking the frugal issue, make sure to check your AC
installation. Bad installations with large air gaps around the unit are
a sure way to spend more on cooling than you need to. That foam used to
seal up around gaps and between the window and AC wears out and falls
apart over time. If you have a year-round installed air conditioner
check and replace and foam strips sealing up gaps and replace it as
necessary.
Rick
Rick
James
> Dave wrote:
>
> > "Joe" <joe5...@gmail.com> wrote in message
>
> - Show quoted text -
The other thing is to clean filters.
My window units both have removable filters that can be rinsed clean,
and I have noticed a big difference in cooling between a clean filter
and a dirty one. Presumably that should mean less electricity use too.
I don't have a/c in the basement - with only small windows it doesn't
heat up as much. I use a dehumidifier to take the moisture out of the
air, and I think its more efficient at it than the AC units upstairs.
James
nicks...@ece.villanova.edu
>... Fans won't help a bit if the humidity level is too high. The
>fans just circulate HUMID air.
And make you feel cooler...
Nick
Bob F
"Joe" <joe...@gmail.com> wrote in message
news:1183999637.3...@k79g2000hse.googlegroups.com...
Turn on the fans. Go watch your electric meter, and time how many
times the disc goes around in a minute. Then turn off the fans, turn
on the A/C, and do the meter thing again. Which one turned the most?
If the fans were even close to the A/C, the A/C might be cheaper,
since the compressor will likely cycle off part of the time.
Bob
Bob F
"James" <jl...@idirect.com> wrote in message
news:1184013561.1...@o61g2000hsh.googlegroups.com...
> I don't have a/c in the basement - with only small windows it
> doesn't
> heat up as much. I use a dehumidifier to take the moisture out of
> the
> air, and I think its more efficient at it than the AC units
> upstairs.
A dehunidifier is just an A/C that returns the heat to the room air
after it cools it. There is no reason it should be inherently more
efficient. Using an A/C in the basement instead of the dehumidifier
might cut down your total energy usage, as it would somewhat reduce
the heat gain from the basement to the rest of the house.
Bob
Tockk
I had a 5500 BTU window unit that drew about 700 watts. Your average
window fan draws about 50 watts.
You should be able to get exact information just by looking at the labels on
your ac and your fans. Add up the wattage for each, and you'll have the
info you seek.
I'll guess that your AC unit draws about 1400 watts, about the same as a
blow dryer for hair.
I'll guess that your six fans draw 50 watts each, for a total of 300 watts.
If you're paying 10 cents per KWH for electricity, your AC is costing you 14
cents per hour to run.
And you're paying 3 cents per hour to run your fans.
If you run the AC for 18 hours a day, that'll cost you $2.52 a day, or
$75.60 a month.
If you run the fans for 18 hours a day, that'll cost you 54 cents a day, or
$16.20 a month.
That's a difference of $59.40 a month.
Logan Shaw
It's hard to do the exact math without knowing the real-world numbers
on those fans and that air conditioner.
However, just as a starting point, I just measured a box fan with
my Kill-a-Watt. It draws 75W on low, 90W on medium, and 110W on
high[1].
So if you have 6 fans similar to my fan, and they're on all the time,
you're drawing something like 450W to 650W.
It gets a little trickier here because there are too many unknowns
to come up with a number. An A/C unit at a given thermostat setting
will run more in a hot climate and less in a mild climate (whereas
the fans draw a constant amount of power). Also, it depends on the
efficiency of the unit.
However, some googling indicates an 11000 BTU A/C unit might draw
something like 1250-1500W while it's running at "full steam".
So the question then becomes pretty simple: what's the duty cycle
of the A/C unit? If it's on 1/3 of the time and off 2/3 of the
time, then you're approximately breaking even on energy usage.
Two parts 0W and one part 1500W averages out to 500W, the same as
the fans.
- Logan
[1] And incidentally, based on the fact that low makes a G#, medium
makes a C#, and high makes an E (roughly), the high setting
seems to be more efficient. Rising from a G# to an E represents
a ratio of about 1.6 in frequency, and 110W/75W is a ratio of
about 1.45. So assuming speed translates linearly to airflow,
it's more efficient when running on high.
Chois...@search.aol.com
news:46927efa$0$97236$892e...@authen.yellow.readfreenews.net:
> Fans won't help a bit if the humidity level is too high. The
> fans just circulate HUMID air.
http://www.google.com/search?q=%22heat+transfer%22+rate+%7C++flow+%22temp
erature+differential%22+convection
Chois...@search.aol.com
news:4692dcf8$0$24707$4c36...@roadrunner.com:
> So assuming speed translates linearly to airflow,
> it's more efficient when running on high.
a related chart/graph, but i didn't want to dig further. :-)
http://www.fsec.ucf.edu/en/publications/html/FSEC-PF-411-04/index.htm
Chois...@search.aol.com
news:Xns9969C...@216.196.97.142:
nah, looking over this, it looks like the voltage is the value they're comparing to
"efficiency" or cfm. not applicable to this topic.
maybe some more searching will find a flow vs power graph for a blade similar to
boxfan blade.