Anyone done any sort of calculations or theories to see if running a
separate dehumidifier in a basement cuts down any central air
conditioner run time on the rest of the house?

Increases, as the dehum puts out heat.
..
Christopher A. Young
Learn more about Jesus
www.lds.org
..
..
"Hench" wrote in message ...
Anyone done any sort of calculations or theories to see if running a
separate dehumidifier in a basement cuts down any central air
conditioner run time on the rest of the house?

On 5/21/2013 9:38 PM, Stormin Mormon wrote:
Increases, as the dehum puts out heat.
.

but how much heat? If I have a 10 seer 1.5 ton a/c that's 18 000 btu
removed per hour, if my memory is correct.

But if the air is drier, then the human body can handle a higher
temperature, thus the a/c would be run less?

Or so the theory goes...

"Stormin Mormon" wrote:
Increases, as the dehum puts out heat.
.
Christopher A. Young
Learn more about Jesus
www.lds.org
.
.
"Hench" wrote in message ...
Anyone done any sort of calculations or theories to see if running a
separate dehumidifier in a basement cuts down any central air
conditioner run time on the rest of the house?

This heat can be good if air conditioner is over sized, and get proper
dehumidification.

Greg

You'd have to check the watts of the dehum. IIRC, 1500 watts an hour is 5200 BTU per hour.
..
Christopher A. Young
Learn more about Jesus
www.lds.org
..
..
"Hench" wrote in message ...
On 5/21/2013 9:38 PM, Stormin Mormon wrote:
Increases, as the dehum puts out heat.
.

but how much heat? If I have a 10 seer 1.5 ton a/c that's 18 000 btu
removed per hour, if my memory is correct.

But if the air is drier, then the human body can handle a higher
temperature, thus the a/c would be run less?

Or so the theory goes...

Hench wrote:

Anyone done any sort of calculations or theories to see if running a
separate dehumidifier in a basement cuts down any central air
conditioner run time on the rest of the house?

Since the basement is cooler, you'd be better off putting the
dehumidifier in the warmest, most humid place in the house - usually
upstairs. Remember, warm air can carry more water vs cool air.

But the efficiency of small portable dehumidifiers is crap, so the heat
they put out is more of a load on your A/C vs the good they do at
removing a quart or so of water an hour.

Clean your A/C evap and condenser coils - that'll do way more good vs
putzing with the dehumidifier.

Another way to get a bit more humidity out of your indoor air is to run the melt water drain line on the back of your frost free fridge into a drain.

When a frost free fridge goes into it's defrost cycle, it has an electric heater that melts the frost off the evaporator coils. That melt water then flows down a tube into a receiving pan which is typically around or above the warm compressor. Thus, that melt water just gets re-evaporated into the ambient air in your kitchen. Directing that melt water into a drain helps dehumidify your house a bit by preventing the melt water from being re-evaporated into your ambient air.

The melt water drain tube will typically be a black rubber tube running under the condensor tubing on the back of the fridge from the back of the freezer compartment to the bottom of the fridge where the compressor is. You can just drill a hole through the floor and add an additional length of tubing to run the melt water into a floor drain in your basement or whatever. We're not talking about much water, but we're not talking about much expense for 20 feet of vinyl tubing either.

On May 21, 9:38*pm, "Stormin Mormon"
wrote:
Increases, as the dehum puts out heat.

That's for sure. If you use the AC to take out the humidity, it's
dumping the heat generated by the compressor outside and
also taking heat from the house and moving it outside too.
With a dehumidifier, it's only removing humidity, while adding heat.

Only reason I can see for using the dehumidifier would be if the
system is so oversized that the house gets cooled off without
taking out enough humidity.

On Tue, 21 May 2013 21:38:07 -0400, "Stormin Mormon"
wrote:

Increases, as the dehum puts out heat.

I would agree, though it's not that simple. If all of the water that
was taken out in the basement were to end up in the upper floors
(doubtful) much of that energy would have to be used by the AC. The
AC, being larger, will likely be more efficient but it's not just
adding the two together.

Here you may get something of your interest http://destech.eu

On Wednesday, May 22, 2013 at 5:08:48 AM UTC-4, trader_4 wrote:
On May 21, 9:38*pm, "Stormin Mormon"
wrote:
Increases, as the dehum puts out heat.

That's for sure. If you use the AC to take out the humidity, it's
dumping the heat generated by the compressor outside and
also taking heat from the house and moving it outside too.
With a dehumidifier, it's only removing humidity, while adding heat.

Does it really add heat?

Well, sure, a little from the operation of the motor and compressor.

But in the sense of an AC unit, not really. An AC unit has a small amount of heat generated by the operation of the compressor, and a huge amount of heat MOVED from inside the house to outside the house. (A heat pump does the reverse in cold weather).

A dehumidifier doesn't do that. It operates the same way an AC does, but it only moves the heat from the front of the unit to the back of the unit. So that heat movement is a wash.

I would think a whole house AC with reheat would be more efficient than a normal AC plus a separate dehumidifier though.

On Wednesday, February 4, 2015 at 8:14:14 AM UTC-5, TimR wrote:
On Wednesday, May 22, 2013 at 5:08:48 AM UTC-4, trader_4 wrote:
On May 21, 9:38*pm, "Stormin Mormon"
wrote:
Increases, as the dehum puts out heat.

That's for sure. If you use the AC to take out the humidity, it's
dumping the heat generated by the compressor outside and
also taking heat from the house and moving it outside too.
With a dehumidifier, it's only removing humidity, while adding heat.

Does it really add heat?

Well, sure, a little from the operation of the motor and compressor.

Note that this is an old thread, which has just been revived.
But yes, that's the heat I was referring to. How much is a little
depends on your perspective. It's not unusual for dehumidifiers
to cost $30 a month to run. Some folks probably have small electric
heaters that they use that use a similar amount. And that $30
produces the same amount of heat via the dehumidifier. Is it
going to significantly raise the temp of a house? No, but it's
still added heat.



But in the sense of an AC unit, not really. An AC unit has a small amount of heat generated by the operation of the compressor, and a huge amount of heat MOVED from inside the house to outside the house. (A heat pump does the reverse in cold weather).

A dehumidifier doesn't do that. It operates the same way an AC does, but it only moves the heat from the front of the unit to the back of the unit. So that heat movement is a wash.

Yes, that portion is. But you still have $30 worth, or whatever the
monthly bill is, of electric energy being dumped inside the house. With
the central AC, only the blower portion is contributing heat. The
much larger compressor load is losing it's heat outside.



I would think a whole house AC with reheat would be more efficient than a normal AC plus a separate dehumidifier though.

IDK, but I say it's a moot point, because whenever I've had a humidity
issue in the house, putting on the AC, dropping the temperature 2F,
took care of it. In other words, the humidity only becomes a problem
when some AC is also desirable, or at least not objectionable.

On Wednesday, February 4, 2015 at 8:34:08 AM UTC-5, trader_4 wrote:
Note that this is an old thread, which has just been revived.
But yes, that's the heat I was referring to. How much is a little
depends on your perspective. It's not unusual for dehumidifiers
to cost $30 a month to run. Some folks probably have small electric
heaters that they use that use a similar amount. And that $30
produces the same amount of heat via the dehumidifier. Is it
going to significantly raise the temp of a house? No, but it's
still added heat.


Okay, I see your point, and agree. Note that I was in error saying a dehumidifier moves heat from the front to the back of the unit. It does, but it also dumps heat down the drain in the form of condensed water. Some of that water may absorb heat from the dehumidifier as it warms up after it comes off the coil, so it's probably not $30. Might be $29.50.

I would think a whole house AC with reheat would be more efficient than a normal AC plus a separate dehumidifier though.

IDK, but I say it's a moot point, because whenever I've had a humidity
issue in the house, putting on the AC, dropping the temperature 2F,
took care of it. In other words, the humidity only becomes a problem
when some AC is also desirable, or at least not objectionable.

An AC reduces humidity but doesn't control it. Whether that reduction is enough depends mostly on luck, a little bit on getting the size of the unit correct. You can control it with a humidistat and reheat, that's going to take more electricity use though.

On 2/4/2015 12:41 PM, TimR wrote:
to cost $30 a month to run. Some folks probably have small electric
heaters that they use that use a similar amount. And that $30
produces the same amount of heat via the dehumidifier. Is it
going to significantly raise the temp of a house? No, but it's
still added heat.


Okay, I see your point, and agree. Note that I was in
error saying a dehumidifier moves heat from the front to
the back of the unit. It does, but it also dumps heat
down the drain in the form of condensed water. Some of
that water may absorb heat from the dehumidifier as it
warms up after it comes off the coil, so it's probably
not $30. Might be $29.50.


CY: The dehum moves heaat from the back (cold) to the front
(blows out warm). Water releases heat as it condenses, so
as the water turns from vapor to liquid, it released more
heat into the room. Which heat is blown out the front of the
dehum.

An AC reduces humidity but doesn't control it. Whether
that reduction is enough depends mostly on luck, a little
bit on getting the size of the unit correct. You can control
it with a humidistat and reheat, that's going to take more
electricity use though.


CY: That makes sense.
-
..
Christopher A. Young
learn more about Jesus
.. www.lds.org
..
..

On Wednesday, February 4, 2015 at 2:34:16 PM UTC-5, Stormin Mormon wrote:
CY: The dehum moves heaat from the back (cold) to the front
(blows out warm). Water releases heat as it condenses, so
as the water turns from vapor to liquid, it released more
heat into the room. Which heat is blown out the front of the
dehum.


Much as I hate to admit it, you're right. I had brain cramp, obviously.

The heat transfer to cool the air down to dewpoint is a wash, just moves from back to front. The heat transfer to make the water change state from gas to liquid is a net gain to the room.

On 2/4/2015 8:14 AM, TimR wrote:

Does it really add heat?

Well, sure, a little from the operation of the motor and compressor.

But in the sense of an AC unit, not really. An AC unit has a small amount of heat generated by the operation of the compressor, and a huge amount of heat MOVED from inside the house to outside the house. (A heat pump does the reverse in cold weather).

A dehumidifier doesn't do that. It operates the same way an AC does, but it only moves the heat from the front of the unit to the back of the unit. So that heat movement is a wash.

I would think a whole house AC with reheat would be more efficient than a normal AC plus a separate dehumidifier though.



Dehum adds both the heat from the motor,
and also the heat which is called "latent
heat of vaporization" which comes into
play when a liquid changes to a vapor. Or,
in this case a vapor to a liquid. When water
vapor condenses, it releases a LOT of heat.

Free standing dehum release a lot of heat.

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

On 2/4/2015 3:46 PM, TimR wrote:
On Wednesday, February 4, 2015 at 2:34:16 PM UTC-5, Stormin Mormon wrote:
CY: The dehum moves heaat from the back (cold) to the front
(blows out warm). Water releases heat as it condenses, so
as the water turns from vapor to liquid, it released more
heat into the room. Which heat is blown out the front of the
dehum.


Much as I hate to admit it, you're right.

I had brain cramp, obviously.

The heat transfer to cool the air down to dewpoint
is a wash, just moves from back to front. The heat
transfer to make the water change state from gas to
liquid is a net gain to the room.


Just to be OCD, here. Please include the electric
motor in the compressor, which releases heat.

Brain cramp. No big deal, some times I forget the

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

On Wednesday, February 4, 2015 at 4:27:57 PM UTC-5, Stormin Mormon wrote:

Just to be OCD, here. Please include the electric
motor in the compressor, which releases heat.

Nope. Not gonna do that. If I did that, I'd have to include the heat the motor in the ceiling fan adds, and that means ceiling fans are a bad idea, and nobody wants to hear that.

On Thursday, February 5, 2015 at 8:09:42 AM UTC-5, TimR wrote:
On Wednesday, February 4, 2015 at 4:27:57 PM UTC-5, Stormin Mormon wrote:

Just to be OCD, here. Please include the electric
motor in the compressor, which releases heat.

Nope. Not gonna do that. If I did that, I'd have to include the heat the motor in the ceiling fan adds, and that means ceiling fans are a bad idea, and nobody wants to hear that.

You already did include it. We were talking about a dehumidifier that
uses say $30 worth of electricity a month. That $30 includes the heat
that's generated by the compressor motor. Essentially all that $30 winds
up as heat in the room.

On Thursday, February 5, 2015 at 8:48:45 AM UTC-5, trader_4 wrote:


You already did include it. We were talking about a dehumidifier that
uses say $30 worth of electricity a month. That $30 includes the heat
that's generated by the compressor motor. Essentially all that $30 winds
up as heat in the room.

I'm sure you know but it may not be obvious to all that the $30 for operation of the equipment does not include the heat generated by phase change of the water being condensed.

Air conditioners use a given amount of electricity to produce a given amount of work.

But they move about 5 times as much heat as the work that is input. Some of that heat is latent heat.

On Thursday, February 5, 2015 at 10:47:41 AM UTC-5, TimR wrote:
On Thursday, February 5, 2015 at 8:48:45 AM UTC-5, trader_4 wrote:


You already did include it. We were talking about a dehumidifier that
uses say $30 worth of electricity a month. That $30 includes the heat
that's generated by the compressor motor. Essentially all that $30 winds
up as heat in the room.

I'm sure you know but it may not be obvious to all that the $30 for operation of the equipment does not include the heat generated by phase change of the water being condensed.


The $30 includes all the heat energy added to the room period. Draw
a closed box around the room with the dehumidifier in it. Whatever
energy, ie the $30 worth of electricity, comes into that closed room,
is heat that is added to the room.


Air conditioners use a given amount of electricity to produce a given amount of work.

But they move about 5 times as much heat as the work that is input. Some of that heat is latent heat.

It's a dehumidifier. It can move 5x, but it's moving it from one
side of the unit to the other. The moving doesn't add to or subtract from
the heat in the room. What does add to the heat in the room is the
$30 worth of electrical energy that is added over the course of a month
and which winds up as heat.

On Thursday, February 5, 2015 at 11:44:56 AM UTC-5, trader_4 wrote:
Air conditioners use a given amount of electricity to produce a given amount of work.

But they move about 5 times as much heat as the work that is input. Some of that heat is latent heat.

It's a dehumidifier. It can move 5x, but it's moving it from one
side of the unit to the other. The moving doesn't add to or subtract from
the heat in the room. What does add to the heat in the room is the
$30 worth of electrical energy that is added over the course of a month
and which winds up as heat.

No, Stormy is right on this one.

Put 10 watthours (or Btus or whatever you want) of electric energy into it.

Get 10 watthours of heat energy dumped to the room as waste.

Also get 50 watthours of heat energy moved from place to place. BUT! That 50 watthours of energy includes the heat in the air moving from front to back AND the conversion of water vapor to liquid. The moving of the air doesn't add to the heat in the room but the condensing of the water does.

On 2/5/2015 8:09 AM, TimR wrote:
On Wednesday, February 4, 2015 at 4:27:57 PM UTC-5, Stormin Mormon wrote:

Just to be OCD, here. Please include the electric
motor in the compressor, which releases heat.

Nope. Not gonna do that. If I did that, I'd
have to include the heat the motor in the ceiling
fan adds, and that means ceiling fans are a bad
idea, and nobody wants to hear that.

I've not checked lately, but dehum runs 500 watts
or so, and ceiling fan more like 50.

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

On Thursday, February 5, 2015 at 3:58:45 PM UTC-5, Stormin Mormon wrote:


I've not checked lately, but dehum runs 500 watts
or so, and ceiling fan more like 50.


I found a Wisconsin study on humidifier measurements and tried to do some math.

Per the study, electric consumption averaged 6.5 kWhr/day. I used the average rather than the peak of 17 or the low. That 6.5 kWhr will be heat dumped in the room.

Then from the energy star people I found that medium sized humidifiers produce 1.5 liters of water per kWhr, so the average should be 9.75 liters per day.

The latent heat of condensation for water is 2260 kJ/kg. A liter is a kg. So I have 9.75*2260 kJ/day. But a kWhr is 3600 kJ, so I divide by 3600 and get 6.12 kWhr/day latent heat released by condensing the water.

So a dehumidifier on average puts 6.5 kWhr/day of heat into the room from its mechanical operation, plus 6.12 kWhr/day of heat into the room from condensing the water, plus it moves an unknown amount of heat from front to back but we don't care about that.

If I did the math right.

"TimR" wrote in message
...
On Thursday, February 5, 2015 at 3:58:45 PM UTC-5, Stormin Mormon wrote:


I've not checked lately, but dehum runs 500 watts
or so, and ceiling fan more like 50.


I found a Wisconsin study on humidifier measurements and tried to do some
math.

Per the study, electric consumption averaged 6.5 kWhr/day. I used the
average rather than the peak of 17 or the low. That 6.5 kWhr will be heat
dumped in the room.

Then from the energy star people I found that medium sized humidifiers
produce 1.5 liters of water per kWhr, so the average should be 9.75 liters
per day.

The latent heat of condensation for water is 2260 kJ/kg. A liter is a kg.
So I have 9.75*2260 kJ/day. But a kWhr is 3600 kJ, so I divide by 3600 and
get 6.12 kWhr/day latent heat released by condensing the water.

So a dehumidifier on average puts 6.5 kWhr/day of heat into the room from
its mechanical operation, plus 6.12 kWhr/day of heat into the room from
condensing the water, plus it moves an unknown amount of heat from front
to back but we don't care about that.

Not doubting the math, but where did the enegery come from to condense the
water ? One minor fly in the oinment.

On 2/5/2015 5:16 PM, Ralph Mowery wrote:
So a dehumidifier on average puts 6.5 kWhr/day of heat into the room from
its mechanical operation, plus 6.12 kWhr/day of heat into the room from
condensing the water, plus it moves an unknown amount of heat from front
to back but we don't care about that.

Not doubting the math, but where did the enegery come from to condense the
water ? One minor fly in the oinment.


As the air / vapor mix gets colder near the
evaporator, the capacity of the air is reduced.

As the water condenses on the evaporator, it
releases energy.

I'd dare to guess it's a release of energy,
overall.

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

On Thursday, February 5, 2015 at 12:00:00 PM UTC-5, TimR wrote:
On Thursday, February 5, 2015 at 11:44:56 AM UTC-5, trader_4 wrote:
Air conditioners use a given amount of electricity to produce a given amount of work.

But they move about 5 times as much heat as the work that is input. Some of that heat is latent heat.

It's a dehumidifier. It can move 5x, but it's moving it from one
side of the unit to the other. The moving doesn't add to or subtract from
the heat in the room. What does add to the heat in the room is the
$30 worth of electrical energy that is added over the course of a month
and which winds up as heat.

No, Stormy is right on this one.

Put 10 watthours (or Btus or whatever you want) of electric energy into it.

On Friday, February 6, 2015 at 7:43:39 AM UTC-5, trader_4 wrote:
Wrong. It would be a gross violation of the principle of
conservaton of energy if somehow heat was miraculously added to
the room. The dehumidifier moves heat from one place to
another. The conversion of water vapor to liquid is exactly that,
the movement of heat within the room. It does not add or remove
heat from the room. Phase changes don't affect the total energy
within the assumed perfectly insulated room. The only total heat
change in the room in your example is the


Okay, Stormy, over to you to defend this one. It was your idea. I think trader is wrong but I'm not 100%.

On 2/8/2015 2:59 PM, TimR wrote:
On Friday, February 6, 2015 at 7:43:39 AM UTC-5, trader_4 wrote:
Wrong. It would be a gross violation of the principle of
conservaton of energy if somehow heat was miraculously added to
the room. The dehumidifier moves heat from one place to
another. The conversion of water vapor to liquid is exactly that,
the movement of heat within the room. It does not add or remove
heat from the room. Phase changes don't affect the total energy
within the assumed perfectly insulated room. The only total heat
change in the room in your example is the


Okay, Stormy, over to you to defend this one. It was your
idea. I think trader is wrong but I'm not 100%.


Trader's right about not changing the total energy.

However, the phase change takes latent heat of
vaporization, and changes it to sensible heat (to wit,
party of the second part), that being rise in
temperature.

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

On Sunday, February 8, 2015 at 3:59:02 PM UTC-5, Stormin Mormon wrote:
On 2/8/2015 2:59 PM, TimR wrote:
On Friday, February 6, 2015 at 7:43:39 AM UTC-5, trader_4 wrote:
Wrong. It would be a gross violation of the principle of
conservaton of energy if somehow heat was miraculously added to
the room. The dehumidifier moves heat from one place to
another. The conversion of water vapor to liquid is exactly that,
the movement of heat within the room. It does not add or remove
heat from the room. Phase changes don't affect the total energy
within the assumed perfectly insulated room. The only total heat
change in the room in your example is the


Okay, Stormy, over to you to defend this one. It was your
idea. I think trader is wrong but I'm not 100%.


Trader's right about not changing the total energy.

However, the phase change takes latent heat of
vaporization, and changes it to sensible heat (to wit,
party of the second part), that being rise in
temperature.

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

Well, of course he's right, you can't get something for nothing.

However, we're talking about the difference between adding 6.5 kWthr/day of heat to the room, from running the equipment, and 12.62 kWthr, from running the equipment plus the latent heat. We agree since cold air goes out one hole and warm air out another the sensible heat is a wash, but I tend to think the latent heat actually goes into the room.

"TimR" wrote in message
...
Okay, Stormy, over to you to defend this one. It was your
idea. I think trader is wrong but I'm not 100%.


Trader's right about not changing the total energy.

However, the phase change takes latent heat of
vaporization, and changes it to sensible heat (to wit,
party of the second part), that being rise in
temperature.

.
.

Well, of course he's right, you can't get something for nothing.

However, we're talking about the difference between adding 6.5 kWthr/day of
heat to the room, from running the equipment, and 12.62 kWthr, from running
the equipment plus the latent heat. We agree since cold air goes out one
hole and warm air out another the sensible heat is a wash, but I tend to
think the latent heat actually goes into the room.

You are still not accounting for the enegery to condense the water out of
the air. The more humidity in the room ,the more enegery it will take to
cool the room if water is being condensed out of the room.

Here are some more calculations to support that.
https://www.physicsforums.com/thread...ooling.405361/

On Sunday, February 8, 2015 at 7:04:39 PM UTC-5, TimR wrote:
On Sunday, February 8, 2015 at 3:59:02 PM UTC-5, Stormin Mormon wrote:
On 2/8/2015 2:59 PM, TimR wrote:
On Friday, February 6, 2015 at 7:43:39 AM UTC-5, trader_4 wrote:
Wrong. It would be a gross violation of the principle of
conservaton of energy if somehow heat was miraculously added to
the room. The dehumidifier moves heat from one place to
another. The conversion of water vapor to liquid is exactly that,
the movement of heat within the room. It does not add or remove
heat from the room. Phase changes don't affect the total energy
within the assumed perfectly insulated room. The only total heat
change in the room in your example is the


Okay, Stormy, over to you to defend this one. It was your
idea. I think trader is wrong but I'm not 100%.


Trader's right about not changing the total energy.

However, the phase change takes latent heat of
vaporization, and changes it to sensible heat (to wit,
party of the second part), that being rise in
temperature.

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

Well, of course he's right, you can't get something for nothing.

Glad you agree.



However, we're talking about the difference between adding 6.5 kWthr/day of heat to the room, from running the equipment, and 12.62 kWthr, from running the equipment plus the latent heat. We agree since cold air goes out one hole and warm air out another the sensible heat is a wash, but I tend to think the latent heat actually goes into the room.

Sigh.... But apparently not. There is no however. In an ideal, perfectly
insulated room, unless you put some energy from outside into it, the
energy content is fixed. The *only* increase in heat from the dehumidifier
is the 6.5kwhr from the electrical energy added to the room. The latent
heat doesn't go into the room, it's already there.

On Sunday, February 8, 2015 at 7:31:54 PM UTC-5, Ralph Mowery wrote:
"TimR" wrote in message
...
Okay, Stormy, over to you to defend this one. It was your
idea. I think trader is wrong but I'm not 100%.


Trader's right about not changing the total energy.

However, the phase change takes latent heat of
vaporization, and changes it to sensible heat (to wit,
party of the second part), that being rise in
temperature.

.
.

Well, of course he's right, you can't get something for nothing.

However, we're talking about the difference between adding 6.5 kWthr/day of
heat to the room, from running the equipment, and 12.62 kWthr, from running
the equipment plus the latent heat. We agree since cold air goes out one
hole and warm air out another the sensible heat is a wash, but I tend to
think the latent heat actually goes into the room.

You are still not accounting for the enegery to condense the water out of
the air. The more humidity in the room ,the more enegery it will take to
cool the room if water is being condensed out of the room.

Here are some more calculations to support that.
https://www.physicsforums.com/thread...ooling.405361/

The energy to condense the water doesn't change the amount of energy
that's in the room. It's just moving the energy around, ie the energy
goes from the water vapor to the other air gases in the room. The only
net change in heat in an ideal, perfectly insulated room, is the from
the addition of the electricity used to run the dehumidifier. It's
basic conservation of energy.

On Sunday, February 8, 2015 at 8:05:06 PM UTC-5, trader_4 wrote:
On Sunday, February 8, 2015 at 7:04:39 PM UTC-5, TimR wrote:
On Sunday, February 8, 2015 at 3:59:02 PM UTC-5, Stormin Mormon wrote:
On 2/8/2015 2:59 PM, TimR wrote:
On Friday, February 6, 2015 at 7:43:39 AM UTC-5, trader_4 wrote:
Wrong. It would be a gross violation of the principle of
conservaton of energy if somehow heat was miraculously added to
the room. The dehumidifier moves heat from one place to
another. The conversion of water vapor to liquid is exactly that,
the movement of heat within the room. It does not add or remove
heat from the room. Phase changes don't affect the total energy
within the assumed perfectly insulated room. The only total heat
change in the room in your example is the


Okay, Stormy, over to you to defend this one. It was your
idea. I think trader is wrong but I'm not 100%.


Trader's right about not changing the total energy.

However, the phase change takes latent heat of
vaporization, and changes it to sensible heat (to wit,
party of the second part), that being rise in
temperature.

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

Well, of course he's right, you can't get something for nothing.

Glad you agree.



However, we're talking about the difference between adding 6.5 kWthr/day of heat to the room, from running the equipment, and 12.62 kWthr, from running the equipment plus the latent heat. We agree since cold air goes out one hole and warm air out another the sensible heat is a wash, but I tend to think the latent heat actually goes into the room.

Sigh.... But apparently not. There is no however. In an ideal, perfectly
insulated room, unless you put some energy from outside into it, the
energy content is fixed. The *only* increase in heat from the dehumidifier
is the 6.5kwhr from the electrical energy added to the room. The latent
heat doesn't go into the room, it's already there.

Ah. I see what you mean.

Yes, you're right.

But, latent heat has been converted to sensible heat. The air temperature will go up by more than the amount predicted by the 6.5 kWthr of energy added; in fact it will go up by double that amount.

"trader_4" wrote in message
...
However, we're talking about the difference between adding 6.5 kWthr/day
of heat to the room, from running the equipment, and 12.62 kWthr, from
running the equipment plus the latent heat. We agree since cold air goes
out one hole and warm air out another the sensible heat is a wash, but I
tend to think the latent heat actually goes into the room.

Sigh.... But apparently not. There is no however. In an ideal, perfectly
insulated room, unless you put some energy from outside into it, the
energy content is fixed. The *only* increase in heat from the dehumidifier
is the 6.5kwhr from the electrical energy added to the room. The latent
heat doesn't go into the room, it's already there.

I guess that Tim will never get it . That latent heat that comes when the
vapor is condensed comes from needing more power to the dehumidifier. The
more water condensed out , the more power it takes to do it.

Cold air does not go out one hole. Air is drawn in from the side with the
cool coil. The vapor condenses and runs out the bottom. The cool air is
then heated as it blows by the hot coil.

On Sunday, February 8, 2015 at 11:37:49 PM UTC-5, Ralph Mowery wrote:
"trader_4" wrote in message
...
However, we're talking about the difference between adding 6.5 kWthr/day
of heat to the room, from running the equipment, and 12.62 kWthr, from
running the equipment plus the latent heat. We agree since cold air goes
out one hole and warm air out another the sensible heat is a wash, but I
tend to think the latent heat actually goes into the room.

Sigh.... But apparently not. There is no however. In an ideal, perfectly
insulated room, unless you put some energy from outside into it, the
energy content is fixed. The *only* increase in heat from the dehumidifier
is the 6.5kwhr from the electrical energy added to the room. The latent
heat doesn't go into the room, it's already there.

I guess that Tim will never get it . That latent heat that comes when the
vapor is condensed comes from needing more power to the dehumidifier. The
more water condensed out , the more power it takes to do it.

Cold air does not go out one hole. Air is drawn in from the side with the
cool coil. The vapor condenses and runs out the bottom. The cool air is
then heated as it blows by the hot coil.

The dehumidifier is in one closed room.

But it's really not, because the cold water is removed from the room.

On Monday, February 9, 2015 at 6:55:22 AM UTC-5, TimR wrote:
On Sunday, February 8, 2015 at 11:37:49 PM UTC-5, Ralph Mowery wrote:
"trader_4" wrote in message
...
However, we're talking about the difference between adding 6.5 kWthr/day
of heat to the room, from running the equipment, and 12.62 kWthr, from
running the equipment plus the latent heat. We agree since cold air goes
out one hole and warm air out another the sensible heat is a wash, but I
tend to think the latent heat actually goes into the room.

Sigh.... But apparently not. There is no however. In an ideal, perfectly
insulated room, unless you put some energy from outside into it, the
energy content is fixed. The *only* increase in heat from the dehumidifier
is the 6.5kwhr from the electrical energy added to the room. The latent
heat doesn't go into the room, it's already there.

I guess that Tim will never get it . That latent heat that comes when the
vapor is condensed comes from needing more power to the dehumidifier. The
more water condensed out , the more power it takes to do it.

Cold air does not go out one hole. Air is drawn in from the side with the
cool coil. The vapor condenses and runs out the bottom. The cool air is
then heated as it blows by the hot coil.

The dehumidifier is in one closed room.

But it's really not, because the cold water is removed from the room.

That's a new objection. Yes, you can factor that in, but it's a
complication that's then hard to account for. The range of possibilities
could range from the cold water going straight down a drain, to the
cold water accumulating in the bucket inside the dehumidifier, taking
on whatever temp exists inside the area that it sits in, then being
dumped down a drain, to the water staying in the room and used to water
plants. And if it leavest the room, then you have make-up air coming
into the room to replace it. That's why I used the simplified model
of an ideal, perfectly
insulated, closed room. And it seemed like you were OK with that,
because it looked like your argument was that the condensation of water
vapor out of the air changed the amount of heat in the room regardless
of whether that water stayed in the room or left the room. If it
stays in the ideal, closed, perfectly insulated room, then the only
heat change in the room is the change from the electrical energy
flowing into the room to run the dehumidifier. If you want to add the
complication of the condensate leaving the room, then yes, that
energy transfer would also have to be factored in.

On 2/8/2015 8:18 PM, TimR wrote:
Sigh.... But apparently not. There is no however. In an ideal, perfectly
insulated room, unless you put some energy from outside into it, the
energy content is fixed. The *only* increase in heat from the dehumidifier
is the 6.5kwhr from the electrical energy added to the room. The latent
heat doesn't go into the room, it's already there.


But, latent heat has been converted to sensible heat. The
air temperature will go up by more than the amount predicted
by the 6.5 kWthr of energy added; in fact it will go up by
double that amount.


1) The ideal room has an old man with a cigar who
yells at everyone "close the damn door"

2) Most of us humans notice the rise in temperature,
rather than the loss of latent heat which was converted
away.

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

On Monday, February 9, 2015 at 7:35:52 AM UTC-5, trader_4 wrote:

insulated, closed room. And it seemed like you were OK with that,
because it looked like your argument was that the condensation of water
vapor out of the air changed the amount of heat in the room regardless
of whether that water stayed in the room or left the room.

Okay, I see where we're off.

The original question was whether the dehumidifier heated up the room, which to any common sense person means did the air temperature in the room rise..

And the the original answer was yes, by ONLY the amount of energy added by the mechanical operation of the equipment, which we know is an average 6.5 kWtHr/day. The air temperature in the room would rise exactly the amount predicted by adding 6.5 kWthr/day.

That was assuming that the air cooled by the cold coil and reheated by the hot coil never left the room and so heat was moved back and forth but never lost or gained.

But as Stormy pointed out that neglected a factor. There is heat recovered by condensing the water vapor into liquid at the same temperature, and it's a lot of heat. It ends up being an additional 6.1 kWtHr/day.

So I have contended that the temperature in the room will rise by almost double the amount of the 6.5kWthr used.

Where did that 6.1 kWthr/day go? It went into the cold coil, circulated through the refrigerant, and popped out the hot coil into the room air.

The water it came from can't be reheated and reevaporated, because it went down the drain (at least in my house I have the basement dehumidifier piped to the drain).

By the way, that means a humidifier is roughly 190% efficient at heating your house - you put in 6.5 kWthrs of energy and get back 12.6 kWthrs of heat..

On Monday, February 9, 2015 at 8:28:28 AM UTC-5, TimR wrote:
On Monday, February 9, 2015 at 7:35:52 AM UTC-5, trader_4 wrote:

insulated, closed room. And it seemed like you were OK with that,
because it looked like your argument was that the condensation of water
vapor out of the air changed the amount of heat in the room regardless
of whether that water stayed in the room or left the room.

Okay, I see where we're off.

The original question was whether the dehumidifier heated up the room, which to any common sense person means did the air temperature in the room rise.

The actual question was:

"With a dehumidifier, it's only removing humidity, while adding heat.
Does it really add heat? " Words have meaning, especially when you're
talking about physics.




And the the original answer was yes, by ONLY the amount of energy added by the mechanical operation of the equipment, which we know is an average 6.5 kWtHr/day.

That is correct.


The air temperature in the room would rise exactly the amount predicted by
adding 6.5 kWthr/day.

No one said that.



That was assuming that the air cooled by the cold coil and reheated by the hot coil never left the room and so heat was moved back and forth but never lost or gained.

Which is, once again, assuming for purposes of discussion, that it's an ideal
perfectly insulated, closed room.



But as Stormy pointed out that neglected a factor. There is heat recovered by condensing the water vapor into liquid at the same temperature, and it's a lot of heat. It ends up being an additional 6.1 kWtHr/day.

Ralph and I always explicity accounted for the 6.1kwhr of incoming
electrical energy. In fact, I said it's the *only* increase in heat.
There is no extra 6.1 kwh per day of heat.



So I have contended that the temperature in the room will rise by almost double the amount of the 6.5kWthr used.

No, only now are you starting to talk about temperature. I previously
pointed out that I thought you were mixing up heat and temperature.



Where did that 6.1 kWthr/day go? It went into the cold coil, circulated through the refrigerant, and popped out the hot coil into the room air.

No **** Sherlock. At least that's where most of it went, assuming you're
talking here about the actual 6.1 of electrical energy used.


The water it came from can't be reheated and reevaporated, because it went down the drain (at least in my house I have the basement dehumidifier piped to the drain).


We were talking about an ideal, closed, perfectly insulated room, not
your house.




By the way, that means a humidifier is roughly 190% efficient at heating your house - you put in 6.5 kWthrs of energy and get back 12.6 kWthrs of heat.

No idea where than number came from. And once again, you're conflating
*heat* and *temperature*. You could get an increase in temperature, but
not an increase in heat. Good grief.