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Furnace Fan Wattage
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| radezeeuw@yahoo.com 2005-11-17, 1:21 pm |
| We have a natural gas furnace and I am attempting to figure out how
much it costs to run the blower only since we just added a wood
fireplace insert.
The blower fan: =BD HP, 10.2 Amp
Does anybody have a guess as to what would the normal running (not
startup) watts be?
Thanks in advance,
Rick
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<radezeeuw@yahoo.com> wrote in message
news:1132244241.244846.282870@g43g2000cwa.googlegroups.com...
We have a natural gas furnace and I am attempting to figure out how
much it costs to run the blower only since we just added a wood
fireplace insert.
The blower fan: ½ HP, 10.2 Amp
Does anybody have a guess as to what would the normal running (not
startup) watts be?
Thanks in advance,
Rick
assuming 120v A times V equals watts. divide by 1000 for kw
Most but not all fans run pretty close to the name plate depending on the
speed selection.
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| Solar Flare 2005-11-17, 7:21 pm |
| Pretty tough to calculate the power consumed. Speed,
air restriction and efficiency all play big parts in
this.
If your furnace filter is dirty is will decrease the
load as less air is moved.
10.2 A x 120 V x 75% PF = 918 Watts (real rough)
<radezeeuw@yahoo.com> wrote in message
news:1132244241.244846.282870@g43g2000cwa.googlegroups.com...
We have a natural gas furnace and I am attempting to
figure out how
much it costs to run the blower only since we just
added a wood
fireplace insert.
The blower fan: ½ HP, 10.2 Amp
Does anybody have a guess as to what would the normal
running (not
startup) watts be?
Thanks in advance,
Rick
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| daestrom 2005-11-17, 7:21 pm |
|
<radezeeuw@yahoo.com> wrote in message
news:1132244241.244846.282870@g43g2000cwa.googlegroups.com...
>We have a natural gas furnace and I am attempting to figure out how
>much it costs to run the blower only since we just added a wood
>fireplace insert.
>The blower fan: ½ HP, 10.2 Amp
>Does anybody have a guess as to what would the normal running (not
>startup) watts be?
Using the current value can be tricky since motors don't operate at a unity
power factor. But the horsepower makes this easy. 1 hp is equal to 746
watts. So *if* the motor is loaded by the fan right up to the rating, that
would be 373 watts. Running the fan for 24 hours continuous would be 373
watts*24hours/1000 = 8.952 kwh
daestrom
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| Solar Flare 2005-11-17, 9:21 pm |
| Unfortunately single fan motors are very inefficient.
1/4 horsepower motors take about 1 hp to make them run.
They even attach fans and have open frames in them to
keep the heat from destroying them. Lots of wasted
heat.
"daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> wrote in
message news:oE7ff.4230$JQ.782@twister.nyroc.rr.com...
>
> <radezeeuw@yahoo.com> wrote in message
>
news:1132244241.244846.282870@g43g2000cwa.googlegroups.com...
figure out how[color=darkred]
added a wood[color=darkred]
>
>
normal running (not[color=darkred]
>
> Using the current value can be tricky since motors
don't operate at a unity
> power factor. But the horsepower makes this easy. 1
hp is equal to 746
> watts. So *if* the motor is loaded by the fan right
up to the rating, that
> would be 373 watts. Running the fan for 24 hours
continuous would be 373
> watts*24hours/1000 = 8.952 kwh
>
> daestrom
>
>
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| m Ransley 2005-11-17, 10:21 pm |
| Use a clamp on amp meter to measure it. Several I have seen in the
100000btu range take 350-375 watts to run under load, for me thats apx
35$ a month 24x7. Even an old unit with belt was only 25 watts more
than a newer unit I have. Units with VS DC blower motors can run on low
speed at 100 watts, you can get a true 25-50% savings on your utility
bill. Im getting one installed soon, Blower motors consume alot.
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| <radezeeuw@yahoo.com> wrote in message
news:1132244241.244846.282870@g43g2000cwa.googlegroups.com...
We have a natural gas furnace and I am attempting to figure out how
much it costs to run the blower only since we just added a wood
fireplace insert.
The blower fan: ½ HP, 10.2 Amp
Does anybody have a guess as to what would the normal running (not
startup) watts be?
150 to 200 usually
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| m Ransley 2005-11-18, 7:21 am |
| bw go measure your blower, NO AC unit only takes 150-200 watts to run
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| tkgoogle@ktcnslt.com 2005-11-18, 9:21 am |
| radezeeuw@yahoo.com wrote:
> We have a natural gas furnace and I am attempting to figure out how
> much it costs to run the blower only since we just added a wood
> fireplace insert.
>
> The blower fan: =BD HP, 10.2 Amp
>
> Does anybody have a guess as to what would the normal running (not
> startup) watts be?
Measure it..
Do you have a utility power meter outside?
Have you ever noticed the spinning disk on that meter?
Each complete turn represents some known
quantity of energy. Turn on a large load .. it spins faster.. etc..
The is a calibration constant (for the spinning disk) is usually
written on the meter..
For GE meters it's printed in the lower right hand corner..
http://groups.google.com/group/comp...114c6270589?oe=
=3DUTF-8&output=3Dgplai
For lower power consumption devices you'll measure the time the disk
takes to traverse some fraction of a revolution, at high power levels
measure the time it takes to do multiple revolutions.
You can measure power consumption by a variety of methods..
A=2E) Shut off all breakers except AC/furnace.. turn thermostat fan
setting from "auto" to "on" position and time the disk, on the power
meter, takes to complete one revolution.. then do the math..
For instance.. 60 seconds to complete revolution of a meter with
7=2E2kH calibration =3D=3D 3600/60 * 7.2 =3D 432 watt load.
To adjust for multiple spins or fraction of disk spin, use
(3600 * rotations ) / (elapsed time in secs) * (calibration constant)
=3D=3D load.
Note.. 1/5 of turn =3D=3D 0.2 rotations, etc..
B). Calculate differential by first measuring and calculating a base
load, then add
the new load and remeasure.. Subtract the base load from final
calc.. recheck base load after measurement.
P=2ES. My 15yr old furnace blower uses ~480 watts when it is running.
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| daestrom 2005-11-18, 9:21 am |
|
" Solar Flare" <s.flare@hotmail.invalid> wrote in message
news:hNWdnTiT1eybveDeRVn-iQ@golden.net...
> Unfortunately single fan motors are very inefficient.
> 1/4 horsepower motors take about 1 hp to make them run.
> They even attach fans and have open frames in them to
> keep the heat from destroying them. Lots of wasted
> heat.
>
Not even close. You must be thinking of window fans or something. The
single phase motor used in a forced-air furnace is nowhere near that
inefficient. I'd be very much surprised if it uses over 500 watts.
Best thing the OP can do is actually measure the power usage, either with a
portable watt-meter, or use the kwh meter at the service entrance and some
math.
daestrom
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| Solar Flare 2005-11-18, 11:21 pm |
| Even by your own words 500 watts is pretty close to a
HP in consumption.
Here is a study done by Berkley in California.
http://repositories.cdlib.org/cgi/v...93&context=lbnl
If you read the report you will see it clearly showing
a Carrier 1/3 HP motor consuming 500W on low speed with
a large orifice and more than 1.0 HP on high speed with
a large orifice / load. The sales of the study was to
show the higher efficiency of smarter motors and
control circuits.
Measuring the load with a wattmeter is always a good
idea as there are too many factors involved with the
power used to calculate accurately. The hundreeds of
measurement I have been involved in usually astounds
the electrical customers when they find out the furnace
fan on high continuously adds $90.00 per month to their
electric bill.
Many of these people run 1 HP furnace fan motors too.
Fortunately for these small motors the efficiency goes
up with the size. As the measurements in the study the
energy consumption do not depreciate much with lower
fan speed settings
1kW x 24h x 31d x $0.12/kWh = $90 per month.
Moving air with a small inefficient fan motor is not
cheap.
"daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> wrote in
message
news:Gnkff.17205$DL6.548@twister.nyroc.rr.com...
>
> " Solar Flare" <s.flare@hotmail.invalid> wrote in
message
> news:hNWdnTiT1eybveDeRVn-iQ@golden.net...
inefficient.[color=darkred]
run.[color=darkred]
to[color=darkred]
>
> Not even close. You must be thinking of window fans
or something. The
> single phase motor used in a forced-air furnace is
nowhere near that
> inefficient. I'd be very much surprised if it uses
over 500 watts.
>
> Best thing the OP can do is actually measure the
power usage, either with a
> portable watt-meter, or use the kwh meter at the
service entrance and some
> math.
>
> daestrom
>
>
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