Alternative Power sources

Author

Btu and watts

Sudy Nim

2007-09-18, 1:25 pm

I am looking for an optimum sized, one-room air conditioner to be powered by
my generator rated 4000w run 5500w surge to be used during the occasional
power outage. This will be in addition to my well, two sump-pumps, a
refrigerator and a freezer. Is a 6000 Btu possible? Your opinions or
recommendations would be appreciated.

jbickhaus@gmail.com

2007-09-18, 1:25 pm

jbickhaus@gmail.com

2007-09-18, 1:25 pm

jbickhaus@gmail.com

2007-09-18, 1:25 pm

nicksanspam@ece.villanova.edu

2007-09-18, 1:25 pm

>>12,000 btu's = 3520 watts

No... 3520 watts is 12,000 Btu PER HOUR.

Nick

BobG

2007-09-18, 1:25 pm

And just for completeness, 3412 BTUs is a KWhr. (Man I hope I
remembered that correctly. I'm sure if I didn't, I'll find out Real
Soon)

Neon John

2007-09-18, 1:25 pm

On Tue, 18 Sep 2007 15:10:33 GMT, "Sudy Nim" <pseudonym@noplace.com> wrote:

>I am looking for an optimum sized, one-room air conditioner to be powered by
>my generator rated 4000w run 5500w surge to be used during the occasional
>power outage. This will be in addition to my well, two sump-pumps, a
>refrigerator and a freezer. Is a 6000 Btu possible? Your opinions or
>recommendations would be appreciated.
>

RVers routinely run 15kBTU ACs from the 2.8kW Honda EU3000i. Some people report
success with 13.5kBTU ACs on the 2kW EU2000i. RV ACs use special low-inrush
compressors so those sizes probably won't convert directly to window units.

I have run my entire cabin including the 2.5 ton heat pump on a 7kW generator. My
5.5kW generator won't quite start the heat pump. My 10kW generator barely notices.

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Daddy, why doesn't this magnet pick up this floppy?

Duane C. Johnson

2007-09-18, 5:25 pm

jbickhaus@gmail.com wrote:

> "Sudy Nim" <pseudo...@noplace.com> wrote:

[color=darkred]
> From my calculations - 1 ton = 12,000 BTUs = 3520 watts
> so your looking at a 6000 BTU or 1760 watts !

This is nonsense.
Air conditioners are not rated in BTUs.
They are rated in BTU/hour.

And yes, 6000 BTU/hr or 1760 watts. Units of power.
12,000 BTUs = 3520 watts hours. Units of energy.

Duane

--
Home of the $35 Solar Tracker Receiver
http://www.redrok.com/led3xassm.htm [*]
Powered by \ \ \ //|
Thermonuclear Solar Energy from the Sun / |
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USA 55110-3364 === \ |
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Sudy Nim

2007-09-18, 8:25 pm

My 37 year old central AC paper work indicates 2 ton and 22,000Btu. My
equally old through the wall AC specs are 18,000 Btu/hr, 2880 watts and 13
amps. However nether unit will start with my generator. Starting surge must
be huge?

A google search came up with the following: Converting BTU to Watts: Divide
Btu by air conditioner EER rating (new AC is 9.7) or multiply Btu by 0.293.
For a new 6000 Btu unit using 9.7 EER value it is approximately 60% lower,
618 watt versus the multiplying value of 1758 watt. Yah got me! Sudy Nim.

"Neon John" <no@never.com> wrote in message
news:5430f317m3ntf11md0c6l2skib8hghct10@4ax.com...
> On Tue, 18 Sep 2007 15:10:33 GMT, "Sudy Nim" <pseudonym@noplace.com>
wrote:
>
by[color=darkred]
>
> RVers routinely run 15kBTU ACs from the 2.8kW Honda EU3000i. Some people
report
> success with 13.5kBTU ACs on the 2kW EU2000i. RV ACs use special
low-inrush
> compressors so those sizes probably won't convert directly to window
units.
>
> I have run my entire cabin including the 2.5 ton heat pump on a 7kW
generator. My
> 5.5kW generator won't quite start the heat pump. My 10kW generator barely
notices.
>
> John
> --
> John De Armond
> See my website for my current email address
> http://www.neon-john.com
> http://www.johndearmond.com <-- best little blog on the net!
> Tellico Plains, Occupied TN
> Daddy, why doesn't this magnet pick up this floppy?
>

David Williams

2007-09-18, 9:25 pm

-> And just for completeness, 3412 BTUs is a KWhr. (Man I hope I
-> remembered that correctly. I'm sure if I didn't, I'll find out Real
-> Soon)

Well, let's see if it's reasonable. 1 kWh is 3.6e6 joules, or 8.6e5
calories. That's 8.6e5 times the amount of heat that would raise the
temperature of 1 gram of water by 1 degree Celsius.

3412 BTUs would raise the temperature of 3412 pounds of water by 1
degree Fahrenheit. So that's 1551 kg of water by 0.555556 deg. C., or
861 kg of water by 1 deg. C. 861 kg is 8.6e5 grams, near enough.

So, yes, the two amounts of heat are equal.

It's easy enough to figure these things out, especially with a
calculator to hand!

dow

Neon John

2007-09-19, 3:25 am

On Tue, 18 Sep 2007 23:49:11 GMT, "Sudy Nim" <pseudonym@noplace.com> wrote:

>My 37 year old central AC paper work indicates 2 ton and 22,000Btu. My
>equally old through the wall AC specs are 18,000 Btu/hr, 2880 watts and 13
>amps. However nether unit will start with my generator. Starting surge must
>be huge?
>
>A google search came up with the following: Converting BTU to Watts: Divide
>Btu by air conditioner EER rating (new AC is 9.7) or multiply Btu by 0.293.
>For a new 6000 Btu unit using 9.7 EER value it is approximately 60% lower,
>618 watt versus the multiplying value of 1758 watt. Yah got me! Sudy Nim.

I'm not surprised that your old boat-anchors won't start on your generator. Either
unit probably uses as much power as a 3 or 4 ton modern unit and the inrush is surely
much worse. When you get a chance, why not read the nameplate and post the ratings?
It would be interesting to be reminded of just how bad things used to be.

BTW, SEERs for modern central units are much better than 9.7. My run-of-the-mill
Rheem unit is either a 12 or 13, don't recall which. It is very miserly with
electricity, nice both from my generator's perspective and my power bill's.

John

--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
I'm so cool, I'm afraid to catch a cold.

Mike Ruskai

2007-09-19, 9:25 am

On or about Tue, 18 Sep 2007 15:10:33 GMT did "Sudy Nim"
<pseudonym@noplace.com> dribble thusly:

>I am looking for an optimum sized, one-room air conditioner to be powered by
>my generator rated 4000w run 5500w surge to be used during the occasional
>power outage. This will be in addition to my well, two sump-pumps, a
>refrigerator and a freezer. Is a 6000 Btu possible? Your opinions or
>recommendations would be appreciated.

Divide the BTU rating by the EER to get the number of watts.

So a 6000 BTU window unit with an EER of 10.0 (which is nothing rare
these days) would take 600 watts.

Between that, the fridge, and the freezer, you'd probably have
something like 2500 watts of capacity left to run your pumps. That
sounds a bit short to me, but it depends on how beefy those pumps are.

Steve Ackman

2007-09-19, 8:25 pm

In <JTRHi.106844$ax1.94633@bgtnsc05-news.ops.worldnet.att.net>, on Tue,
18 Sep 2007 15:10:33 GMT, Sudy Nim, pseudonym@noplace.com wrote:
> I am looking for an optimum sized, one-room air conditioner to be powered by
> my generator rated 4000w run 5500w surge to be used during the occasional
> power outage. This will be in addition to my well, two sump-pumps, a
> refrigerator and a freezer. Is a 6000 Btu possible? Your opinions or
> recommendations would be appreciated.

Our Frigidaire window unit:

dataplate:
----------
BTU - 10,000
EER - 10.8
115 VAC
AMPS - 9.7

Kill-a-watt reading:
--------------------
Fan only - 160/180/200 watts
+ Compressor - with low fan, starts out at ~650 watts,
varies up and down to ~700 watts. Fan on high, gets
up around 900 watts... maybe it draws more when it's
actually hot out. We certainly don't need any AC
today... I just turned it on to get some numbers in
addition to those on the dataplate.

Power factor is .85 when the compressor first comes
on, moves up to about .9 after the air begins to get
fairly cool. I only let the compressor run for about
2 minutes, so I won't know what it might do after
running for 10 or 20 minutes until next summer.

As to whether it would run off *your* generator,
that's tough to say. Motors starting under load aren't
so predictable. I can run all four motors on my 220v
coffee roaster simultaneously, yet my 120v 15 amp air
compressor won't start when plugged into a 20 amp
outlet on my 5000W (6250W surge) genset.

Sudy Nim

2007-09-19, 8:25 pm

"Neon John" <no@never.com> wrote in message
news:u7b1f3hsp8adakk6jc8c3um38m8rvrqtf1@4ax.com...
> On Tue, 18 Sep 2007 23:49:11 GMT, "Sudy Nim" <pseudonym@noplace.com>
wrote:
>
13[color=darkred]
must[color=darkred]
Divide[color=darkred]
0.293.[color=darkred]
lower,[color=darkred]
>
> I'm not surprised that your old boat-anchors won't start on your
generator. Either
> unit probably uses as much power as a 3 or 4 ton modern unit and the
inrush is surely
> much worse. When you get a chance, why not read the nameplate and post
the ratings?
> It would be interesting to be reminded of just how bad things used to be.
>
> BTW, SEERs for modern central units are much better than 9.7. My
run-of-the-mill
> Rheem unit is either a 12 or 13, don't recall which. It is very miserly
with
> electricity, nice both from my generator's perspective and my power
bill's.
>
> John
>
>
My 2-ton central boat anchor is rated at "only" 230 volts, 14.5 amp
compressor, fan motor 2.2 amp, or 3841 watts. Sudy Nim

JimG64155

2007-09-22, 8:25 pm

On Sep 18, 10:10 am, "Sudy Nim" <pseudo...@noplace.com> wrote:
> I am looking for an optimum sized, one-room air conditioner to be powered by
> my generator rated 4000w run 5500w surge to be used during the occasional
> power outage. This will be in addition to my well, two sump-pumps, a
> refrigerator and a freezer. Is a 6000 Btu possible? Your opinions or
> recommendations would be appreciated.

A few weeks ago I bought a couple of 5000 Btu units to use for a few
days while a new heat pump was being installed.

Although I did not get one, there are 5000 Btu units rated at 11 SEER,
but you have to look real hard for them.

Here is an example: http://www.grainger.com/Grainger/items/4CE64

Another possibility is a mini-split ductless unit, there are some
imports on Ebay that are 13 SEER

Duane C. Johnson

2007-09-22, 8:25 pm

Hi JimG64155;

JimG64155 <jpgiovagnoli@sbcglobal.net> wrote:

> A few weeks ago I bought a couple of 5000 Btu
> units to use for a few days while a new heat
> pump was being installed.

> Although I did not get one, there are 5000 Btu
> units rated at 11 SEER, but you have to look
> real hard for them.

Air conditioners are not rated in Btu which is a
unit of energy.
They are rated in Btu/hr which is a unit of power.

> Here is an example:
> http://www.grainger.com/Grainger/items/4CE64

See, they used Btu/hr, ok they used a shorthand BtuH.

> Another possibility is a mini-split ductless unit,
> there are some imports on Ebay that are 13 SEER

Duane

--
Home of the $35 Solar Tracker Receiver
http://www.redrok.com/led3xassm.htm [*]
Powered by \ \ \ //|
Thermonuclear Solar Energy from the Sun / |
Energy (the SUN) \ \ \ / / |
Red Rock Energy \ \ / / |
Duane C. Johnson Designer \ \ / \ / |
1825 Florence St Heliostat,Control,& Mounts |
White Bear Lake, Minnesota === \ / \ |
USA 55110-3364 === \ |
(651)426-4766 use Courier New Font \ |
redrok@redrok.com (my email: address) \ |
http://www.redrok.com (Web site) ===

danny burstein

2007-09-22, 8:25 pm

> A few weeks ago I bought a couple of 5000 Btu
> units to use for a few days while a new heat
> pump was being installed.

> Although I did not get one, there are 5000 Btu
> units rated at 11 SEER, but you have to look
> real hard for them.

Alas, it's almost impossible to find
out the "starting surge" required when
these, or many other consumer level
motors, kick into action.

And there's a _huge_ difference in
otherwise identical looking units.

--
_____________________________________________________
Knowledge may be power, but communications is the key
dannyb@panix.com
[to foil spammers, my address has been double rot-13 encoded]

Jim

2007-09-23, 5:25 pm

"Duane C. Johnson" <redrok@redrok.com> wrote in message
news:46F5AF50.5010409@redrok.com...
> Hi JimG64155;
>
> JimG64155 <jpgiovagnoli@sbcglobal.net> wrote:
>
[color=darkred]
> Air conditioners are not rated in Btu which is a
> unit of energy.
> They are rated in Btu/hr which is a unit of power.

OK Mr. Picky; I may not be a genius; that was a title thrust vupon me by
forces beyond my control, but IIRC, I have never seen a window unit that
said Btu/hr on the box, they all say BTUs. Put that in your pipe and smoke
it. Jeez, yer as bad as the guy with the shed....

>
>
> See, they used Btu/hr, ok they used a shorthand BtuH.
>
>
> Duane
>
> --
> Home of the $35 Solar Tracker Receiver
> http://www.redrok.com/led3xassm.htm [*]
> Powered by \ \ \ //|
> Thermonuclear Solar Energy from the Sun / |
> Energy (the SUN) \ \ \ / / |
> Red Rock Energy \ \ / / |
> Duane C. Johnson Designer \ \ / \ / |
> 1825 Florence St Heliostat,Control,& Mounts |
> White Bear Lake, Minnesota === \ / \ |
> USA 55110-3364 === \ |
> (651)426-4766 use Courier New Font \ |
> redrok@redrok.com (my email: address) \ |
> http://www.redrok.com (Web site) ===

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