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
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"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...

You'd have to check the watts of the dehum. IIRC, 1500 watts an hour is 5200 BTU per hour.
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Christopher A. Young
Learn more about Jesus
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"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...

"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

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 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 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 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.

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.

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