Wondering which would be more efficient in this situation...

A/C is set at 76 degrees. Dehumidifier is set at 55% RH. it's 67
degrees outside, approximately, but the house is right at 76 because it
was hot yesterday. Outside RH is 80+ percent.

Is it more energy efficient to open all the windows and turn on a fan,
and let the outside air cool the house off (thus forcing the
dehumidifier to run,) or just leave the windows shut at let the A/C do
its thing?

no, this isn't actually a hypothetical... this is exactly what I woke
up to this AM. I chose to open the windows because I like fresh air,
but on reflection didn't know which was really more efficient.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

On Sun, 24 May 2009 09:29:41 -0400, against all advice, something
compelled Nate Nagel , to say:

A/C is set at 76 degrees. Dehumidifier is set at 55% RH. it's 67
degrees outside, approximately, but the house is right at 76 because it
was hot yesterday. Outside RH is 80+ percent.



I don't have an answer for you, but neener neener neener.



The Dalles, Columbia Gorge Regional / The Dalles Municipal Airport
Last Update on 24 May 5:53 PDT


Fair

54°F(12°C) Humidity: 66 %
Wind Speed: NNW 15 MPH
Barometer: 29.97 in (1014.90 mb)
Dewpoint: 43°F (6°C)
Wind Chill: 50°F (10°C)
Visibility: 10.00 Miles


I haven't run anything in my house for days.



--

Don't worry about people stealing an idea. If it's original, you will
have to ram it down their throats.
- Howard Aiken

Steve Daniels wrote:
On Sun, 24 May 2009 09:29:41 -0400, against all advice, something
compelled Nate Nagel , to say:

A/C is set at 76 degrees. Dehumidifier is set at 55% RH. it's 67
degrees outside, approximately, but the house is right at 76 because it
was hot yesterday. Outside RH is 80+ percent.



I don't have an answer for you, but neener neener neener.



The Dalles, Columbia Gorge Regional / The Dalles Municipal Airport
Last Update on 24 May 5:53 PDT


Fair

54°F(12°C) Humidity: 66 %
Wind Speed: NNW 15 MPH
Barometer: 29.97 in (1014.90 mb)
Dewpoint: 43°F (6°C)
Wind Chill: 50°F (10°C)
Visibility: 10.00 Miles


I haven't run anything in my house for days.




yeah, yeah. I would far rather be on top of a mountain somewhere in PA,
or quite frankly where you're at (SWMBO occasionally thinks she wants to
move to the PNW as well) but Our Nation's First Swamp does offer the
benefit of allowing me to be gainfully employed...

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

Nate Nagel wrote:
Steve Daniels wrote:
On Sun, 24 May 2009 09:29:41 -0400, against all advice, something
compelled Nate Nagel , to say:

A/C is set at 76 degrees. Dehumidifier is set at 55% RH. it's
67 degrees outside, approximately, but the house is right at 76
because it was hot yesterday. Outside RH is 80+ percent.



I don't have an answer for you, but neener neener neener.



The Dalles, Columbia Gorge Regional / The Dalles Municipal Airport
Last Update on 24 May 5:53 PDT
Fair
54°F(12°C) Humidity: 66 % Wind Speed: NNW 15 MPH
Barometer: 29.97 in (1014.90 mb) Dewpoint: 43°F (6°C)
Wind Chill: 50°F (10°C) Visibility: 10.00 Miles


I haven't run anything in my house for days.




yeah, yeah. I would far rather be on top of a mountain somewhere in PA,
or quite frankly where you're at (SWMBO occasionally thinks she wants to
move to the PNW as well) but Our Nation's First Swamp does offer the
benefit of allowing me to be gainfully employed...

nate

LOL

"Nate Nagel" wrote in message
Is it more energy efficient to open all the windows and turn on a fan, and
let the outside air cool the house off (thus forcing the dehumidifier to
run,) or just leave the windows shut at let the A/C do its thing?

no, this isn't actually a hypothetical... this is exactly what I woke up
to this AM. I chose to open the windows because I like fresh air, but on
reflection didn't know which was really more efficient.

If the windows are open, the energy to run the dehumidifier is about 98%
wasted. Otherwise, fans are cheaper to run than AC

The AC removes moisture from the air. I'd choose C, none of
the above.

I'd suggest to turn off the dehum. Cause the dehum pumps
heat into the house. It's equivilant to leaving a 750 watt
filament heater running.

Use the AC to cool the house and dry it out. That way, your
electricity is both cooling and drying. At least you won't
be paying for the dehum to pump out heat, and then the AC to
move the heat. The AC will have a lower electric draw when
it's cold out, cause the compressor won't be working as
hard.

At my place, I try to run the AC as little as possible
during the day when it's hot. And then turn the AC on in the
evening when it's cooling down, outside. Have the AC
professionaly serviced and the outdoor unit washed out with
chemicals and a garden hose. Will restore the efficiency
lost to dirt and crud.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Nate Nagel" wrote in message
...
Wondering which would be more efficient in this situation...

A/C is set at 76 degrees. Dehumidifier is set at 55% RH.
it's 67
degrees outside, approximately, but the house is right at 76
because it
was hot yesterday. Outside RH is 80+ percent.

Is it more energy efficient to open all the windows and turn
on a fan,
and let the outside air cool the house off (thus forcing the
dehumidifier to run,) or just leave the windows shut at let
the A/C do
its thing?

no, this isn't actually a hypothetical... this is exactly
what I woke
up to this AM. I chose to open the windows because I like
fresh air,
but on reflection didn't know which was really more
efficient.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

Nate Nagel wrote:
Wondering which would be more efficient in this situation...

A/C is set at 76 degrees. Dehumidifier is set at 55% RH. it's 67
degrees outside, approximately, but the house is right at 76 because it
was hot yesterday. Outside RH is 80+ percent.

Is it more energy efficient to open all the windows and turn on a fan,
and let the outside air cool the house off (thus forcing the
dehumidifier to run,) or just leave the windows shut at let the A/C do
its thing?

no, this isn't actually a hypothetical... this is exactly what I woke
up to this AM. I chose to open the windows because I like fresh air,
but on reflection didn't know which was really more efficient.

nate


http://einstein.atmos.colostate.edu/.../Humidity.html

At 67F and 80% RH, the dew point is 61F. At 76F and 55% RH, the dew
point indoors is 59F. So the absolute humidity is about the same.

As long as it's at least 5F cooler outside than in, I'll probably open
the windows even if the dew point is several degrees higher outside.

I keep a wet/dry bulb thermometer beside my thermostat and turn on my AC
as needed, according to the wet bulb. If the house is humid in the
morning, I can take care of that by running the AC two or three times
for ten minutes or so. The amount I save by letting the house cool at
night is more than I use to reduce the humidity.

I don't try to keep my humidity as low as 55%.

A dehumidifier is an AC that dumps the heat right back in the house. If
it were winter and I wanted to reduce humidity without losing heat, I'd
invest in a heat exchanger, instead.

On Sun, 24 May 2009 09:29:41 -0400, Nate Nagel
wrote:

Wondering which would be more efficient in this situation...

A/C is set at 76 degrees. Dehumidifier is set at 55% RH. it's 67
degrees outside, approximately, but the house is right at 76 because it
was hot yesterday. Outside RH is 80+ percent.

Is it more energy efficient to open all the windows and turn on a fan,
and let the outside air cool the house off (thus forcing the
dehumidifier to run,) or just leave the windows shut at let the A/C do
its thing?

no, this isn't actually a hypothetical... this is exactly what I woke
up to this AM. I chose to open the windows because I like fresh air,
but on reflection didn't know which was really more efficient.

nate


There is no simple answer to the question because you are
missing so many parts of the calculation.

You don't know:

* The delta (the change) of the outside air temperature or the outside
humidity, it will be changing
* How quickly your home will absorb the moisture out of the air, or
release it into the air
* How quickly your home will absorb the heat out of the air, or
release it into the air.
* Exactly how long you are going to be in the home and for what
times.
* How tolerant you are to changes in humidity and temperature and
since this will change with how active you are, we will also need to
factor that in
* Other sources of heat or moisture into your home (this would include
heat gain via insulation etc.
* Other people who might visit and how often you might open a door or
window.

I'm sure I could find a few more issues like sun light clean
or cloudy skies (day and night) etc.

It really is a difficult task to properly measure it which is
why so many sellers of this or that gadget can make all kinds of
claims that don't seem to make much sense.

E Z Peaces wrote:
Nate Nagel wrote:
Wondering which would be more efficient in this situation...

A/C is set at 76 degrees. Dehumidifier is set at 55% RH. it's 67
degrees outside, approximately, but the house is right at 76 because
it was hot yesterday. Outside RH is 80+ percent.

Is it more energy efficient to open all the windows and turn on a fan,
and let the outside air cool the house off (thus forcing the
dehumidifier to run,) or just leave the windows shut at let the A/C do
its thing?

no, this isn't actually a hypothetical... this is exactly what I woke
up to this AM. I chose to open the windows because I like fresh air,
but on reflection didn't know which was really more efficient.

nate


http://einstein.atmos.colostate.edu/.../Humidity.html

At 67F and 80% RH, the dew point is 61F. At 76F and 55% RH, the dew
point indoors is 59F. So the absolute humidity is about the same.

As long as it's at least 5F cooler outside than in, I'll probably open
the windows even if the dew point is several degrees higher outside.

I keep a wet/dry bulb thermometer beside my thermostat and turn on my AC
as needed, according to the wet bulb. If the house is humid in the
morning, I can take care of that by running the AC two or three times
for ten minutes or so. The amount I save by letting the house cool at
night is more than I use to reduce the humidity.

I don't try to keep my humidity as low as 55%.

A dehumidifier is an AC that dumps the heat right back in the house. If
it were winter and I wanted to reduce humidity without losing heat, I'd
invest in a heat exchanger, instead.

I don't need to dehumidify in the *winter* - exactly the opposite.

Summer (well, let's be honest, spring and fall too) here, humidity is
silly high though.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

Nate Nagel wrote:
E Z Peaces wrote:
Nate Nagel wrote:
Wondering which would be more efficient in this situation...

A/C is set at 76 degrees. Dehumidifier is set at 55% RH. it's 67
degrees outside, approximately, but the house is right at 76 because
it was hot yesterday. Outside RH is 80+ percent.

Is it more energy efficient to open all the windows and turn on a
fan, and let the outside air cool the house off (thus forcing the
dehumidifier to run,) or just leave the windows shut at let the A/C
do its thing?

no, this isn't actually a hypothetical... this is exactly what I
woke up to this AM. I chose to open the windows because I like fresh
air, but on reflection didn't know which was really more efficient.

nate


http://einstein.atmos.colostate.edu/.../Humidity.html

At 67F and 80% RH, the dew point is 61F. At 76F and 55% RH, the dew
point indoors is 59F. So the absolute humidity is about the same.

As long as it's at least 5F cooler outside than in, I'll probably open
the windows even if the dew point is several degrees higher outside.

I keep a wet/dry bulb thermometer beside my thermostat and turn on my
AC as needed, according to the wet bulb. If the house is humid in the
morning, I can take care of that by running the AC two or three times
for ten minutes or so. The amount I save by letting the house cool at
night is more than I use to reduce the humidity.

I don't try to keep my humidity as low as 55%.

A dehumidifier is an AC that dumps the heat right back in the house.
If it were winter and I wanted to reduce humidity without losing heat,
I'd invest in a heat exchanger, instead.

I don't need to dehumidify in the *winter* - exactly the opposite.

Summer (well, let's be honest, spring and fall too) here, humidity is
silly high though.

nate

I would depend on the AC to control summer humidity. A dehumidifier
warms the house.

E Z Peaces wrote:
Nate Nagel wrote:
E Z Peaces wrote:
Nate Nagel wrote:
Wondering which would be more efficient in this situation...

A/C is set at 76 degrees. Dehumidifier is set at 55% RH. it's 67
degrees outside, approximately, but the house is right at 76 because
it was hot yesterday. Outside RH is 80+ percent.

Is it more energy efficient to open all the windows and turn on a
fan, and let the outside air cool the house off (thus forcing the
dehumidifier to run,) or just leave the windows shut at let the A/C
do its thing?

no, this isn't actually a hypothetical... this is exactly what I
woke up to this AM. I chose to open the windows because I like
fresh air, but on reflection didn't know which was really more
efficient.

nate


http://einstein.atmos.colostate.edu/.../Humidity.html

At 67F and 80% RH, the dew point is 61F. At 76F and 55% RH, the dew
point indoors is 59F. So the absolute humidity is about the same.

As long as it's at least 5F cooler outside than in, I'll probably
open the windows even if the dew point is several degrees higher
outside.

I keep a wet/dry bulb thermometer beside my thermostat and turn on my
AC as needed, according to the wet bulb. If the house is humid in
the morning, I can take care of that by running the AC two or three
times for ten minutes or so. The amount I save by letting the house
cool at night is more than I use to reduce the humidity.

I don't try to keep my humidity as low as 55%.

A dehumidifier is an AC that dumps the heat right back in the house.
If it were winter and I wanted to reduce humidity without losing
heat, I'd invest in a heat exchanger, instead.

I don't need to dehumidify in the *winter* - exactly the opposite.

Summer (well, let's be honest, spring and fall too) here, humidity is
silly high though.

nate

I would depend on the AC to control summer humidity. A dehumidifier
warms the house.

I do for the most part. Still need a dehumidifier in the basement to
take the edge off when it's not silly hot outside.

I can't imagine how people lived near DC before air conditioning.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

Nate Nagel wrote:
E Z Peaces wrote:
Nate Nagel wrote:
E Z Peaces wrote:
Nate Nagel wrote:
Wondering which would be more efficient in this situation...

A/C is set at 76 degrees. Dehumidifier is set at 55% RH. it's 67
degrees outside, approximately, but the house is right at 76
because it was hot yesterday. Outside RH is 80+ percent.

Is it more energy efficient to open all the windows and turn on a
fan, and let the outside air cool the house off (thus forcing the
dehumidifier to run,) or just leave the windows shut at let the A/C
do its thing?

no, this isn't actually a hypothetical... this is exactly what I
woke up to this AM. I chose to open the windows because I like
fresh air, but on reflection didn't know which was really more
efficient.

nate


http://einstein.atmos.colostate.edu/.../Humidity.html

At 67F and 80% RH, the dew point is 61F. At 76F and 55% RH, the dew
point indoors is 59F. So the absolute humidity is about the same.

As long as it's at least 5F cooler outside than in, I'll probably
open the windows even if the dew point is several degrees higher
outside.

I keep a wet/dry bulb thermometer beside my thermostat and turn on
my AC as needed, according to the wet bulb. If the house is humid
in the morning, I can take care of that by running the AC two or
three times for ten minutes or so. The amount I save by letting the
house cool at night is more than I use to reduce the humidity.

I don't try to keep my humidity as low as 55%.

A dehumidifier is an AC that dumps the heat right back in the
house. If it were winter and I wanted to reduce humidity without
losing heat, I'd invest in a heat exchanger, instead.

I don't need to dehumidify in the *winter* - exactly the opposite.

Summer (well, let's be honest, spring and fall too) here, humidity is
silly high though.

nate

I would depend on the AC to control summer humidity. A dehumidifier
warms the house.

I do for the most part. Still need a dehumidifier in the basement to
take the edge off when it's not silly hot outside.

I can't imagine how people lived near DC before air conditioning.

nate


They wore funny looking triangular shaped hats
and powdered wigs.

TDD

"Nate Nagel" wrote in message
I can't imagine how people lived near DC before air conditioning.

nate


DC has more hot air than most places.

I lived in Philly with no AC as a kid. People did what they could to keep
cool, even slept in parks in some city areas I'm told. After we got
married, I bought an AC for the bedroom the next year, but we manage one
summer with just a fan. A few years later we did the kids bedroom and
downstairs. I've not been without it since. We use it a lot less where we
now live, but it still gets used and makes sleeping so much better.

Nate Nagel wrote:

Wondering which would be more efficient in this situation...

A/C is set at 76 degrees. Dehumidifier is set at 55% RH. it's 67
degrees outside, approximately, but the house is right at 76 because it
was hot yesterday. Outside RH is 80+ percent.

Is it more energy efficient to open all the windows and turn on a fan,
and let the outside air cool the house off (thus forcing the
dehumidifier to run,) or just leave the windows shut at let the A/C do
its thing?

no, this isn't actually a hypothetical... this is exactly what I woke
up to this AM. I chose to open the windows because I like fresh air,
but on reflection didn't know which was really more efficient.

The enthalpy of the inside air is about 29.8 btu/lb. So, in theory,
you're better off opening the windows as long as the enthalpy of the
outside air is less than that.

For 67 degree outside air, the psychrometric calculator says that as
long as the outside RH is less than 89%, the outside air is "better."

In reality, there are a number of factors which will affect your
actual comfort, many of which have been pointed out. So, you'll just
have to try it and see.

On May 24, 8:29*am, Nate Nagel wrote:
Wondering which would be more efficient in this situation...

A/C is set at 76 degrees. *Dehumidifier is set at 55% RH. *it's 67
degrees outside, approximately, but the house is right at 76 because it
was hot yesterday. *Outside RH is 80+ percent.

Is it more energy efficient to open all the windows and turn on a fan,
and let the outside air cool the house off (thus forcing the
dehumidifier to run,) or just leave the windows shut at let the A/C do
its thing?

no, this isn't actually a hypothetical... *this is exactly what I woke
up to this AM. *I chose to open the windows because I like fresh air,
but on reflection didn't know which was really more efficient.

nate

--
replace "roosters" with "cox" to reply.http://members.cox.net/njnagel

What ever makes you feel better, is more efficient. So have a beer.

ransley wrote:
On May 24, 8:29 am, Nate Nagel wrote:
Wondering which would be more efficient in this situation...

A/C is set at 76 degrees. Dehumidifier is set at 55% RH. it's 67
degrees outside, approximately, but the house is right at 76 because it
was hot yesterday. Outside RH is 80+ percent.

Is it more energy efficient to open all the windows and turn on a fan,
and let the outside air cool the house off (thus forcing the
dehumidifier to run,) or just leave the windows shut at let the A/C do
its thing?

no, this isn't actually a hypothetical... this is exactly what I woke
up to this AM. I chose to open the windows because I like fresh air,
but on reflection didn't know which was really more efficient.

nate

--
replace "roosters" with "cox" to reply.http://members.cox.net/njnagel

What ever makes you feel better, is more efficient. So have a beer.

Oddly enough, there's one sitting in front of me as I type this

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

On May 24, 9:57*am, Nate Nagel wrote:
Steve Daniels wrote:
On Sun, 24 May 2009 09:29:41 -0400, against all advice, something
compelled Nate Nagel , to say:

* * A/C is set at 76 degrees. *Dehumidifier is set at 55% RH. *it's 67
* * degrees outside, approximately, but the house is right at 76 because it
* * was hot yesterday. *Outside RH is 80+ percent.

I don't have an answer for you, but neener neener neener.

* * The Dalles, Columbia Gorge Regional / The Dalles Municipal Airport
* * Last Update on 24 May 5:53 PDT

* * Fair

* * 54°F(12°C) Humidity: 66 %
* * Wind Speed: NNW 15 MPH
* * Barometer: 29.97 in (1014.90 mb)
* * Dewpoint: 43°F (6°C)
* * Wind Chill: 50°F (10°C)
* * Visibility: 10.00 Miles

I haven't run anything in my house for days.

yeah, yeah. *I would far rather be on top of a mountain somewhere in PA,
or quite frankly where you're at (SWMBO occasionally thinks she wants to
move to the PNW as well) but Our Nation's First Swamp does offer the
benefit of allowing me to be gainfully employed...

nate

--
replace "roosters" with "cox" to reply.http://members.cox.net/njnagel

We ain't in the mountains of PA, but we're pretty close. Here's our
forecast.

Tonight...Partly cloudy. Lows in the mid 40s. Light north winds.

Memorial Day...Sunny. Highs in the lower 70s. Light winds... Becoming
northeast 10 to 15 mph.

Monday Night...Mainly clear. Lows in the lower 40s. Northeast winds 10
to 20 mph...becoming east.

Tuesday...Mostly cloudy with rain becoming likely in the afternoon.
Breezy and cooler with highs in the lower 60s. Southeast winds 15 to
25 mph. Chance of rain 70 percent.

Tuesday Night...Rain likely. Breezy with lows in the mid 40s.
Southeast winds 15 to 25 mph...becoming south. Chance of rain 70
percent.

Wednesday...Rain. Highs in the upper 60s. Chance of rain 80 percent.

Wednesday Night...Rain likely. Lows in the lower 50s. Chance of rain
70 percent.

Thursday...Rain. Highs around 70. Chance of rain 80 percent.

Thursday Night...Cloudy with a 50 percent chance of showers. Lows in
the upper 40s.

Friday...Partly sunny. Highs in the upper 60s.

Friday Night...Partly cloudy. Lows in the lower 40s.

Saturday...Sunny. Highs around 70.

Saturday Night...Mainly clear. Lows in the lower 40s.

Sunday...Sunny. Highs in the mid 70s.

--------------------------------------------------

FWIW, I think the most efficient would be to shut off the dehumidier,
cool the house using the outside air, then closing the windows and
turning on the AC or dehumid.