Unless you run an evaporative cooler like we do. Best invention since
One has to get used to it. I feel much more comfortable than with
traditional A/C but we have to make sure to always use coasters for
drinks such as beer that just came out of the fridge. Else there'll be
ugly water stains developing on the table.
They can also help in more humid climates, not as a direct cooler but as
a pre-cool stage outside, before the A/C condenser. However, my
impression is that much of the A/C industry is stuck in the times of the
Flintstones when it comes to innovation.
Of course this does not work in places where the humidity hovers around
90% a lot such as Houston.
You might see a difference when the fan is first turned on, but once the
air is mixed up it shouldn't change. The fan itself doesn't warm or cool
the air in the room.
I have watched my thermometer (digital thermostat directly beneath the
ceiling fan), and there is no change in temperature whether the fan is
turned on or not. But the gentle breeze still "feels" cooler on a hot day.
I tried having my fan blow upwards, and could feel a nice breeze along the
walls where the air is being pushed down. But I don't spend a lot of time
up against the walls, and it's still a lot more disperse than directly
under a down blowing fan.
On Fri, 4 Jul 2014 16:13:56 +0000 (UTC), HerHusband
Well, I can tell you from experience (very recent) it makes a
difference. Big air conditioned room. 33C at the ceiling, 16C at the
floor. Turned on 2 big-assed (no-not the brand name) fans and dropped
the ceiling temp to 24, and raised the floor temperature to 22C within
a few minutes. Did it change the amount of heat in the room? Not at
all. At less than 30 watts each they did not contribute very many
BTUs, but it sure changed the temperature in MOST of the room. The
thermostat was set to 24C. We reset it to 26C after installing the
fans. Will likely get more adjustment over the coming days.
You are not getting my point. The AC, if oversized, moves a lot of
air over the cold colil for a short amount of time while drawing large
amount of current and removing a small amount of humidity.
A smaller A/C moves less air over the cold coil for a longer period of
time, and moves more air to reduce the temperature by the same amount,
using less power to do so. so it removes more moisture for the same
amount of current drawn. The BTU/watt efficiency may very well be the
same - or the big one may even be more efficient - but the efficiency
as a dehumidifier is significantly better on the smaller A/C unit.
If it is not cool enough to require air conditioning, but is too humid
for comfort, running a small de-humidifier is a LOT more efficient
than running the big-assed air conditioner AND the furnace!!!!
Only a total idiot would run the AC and heat at the same time to
reduce the humidity in the house.
As for the de-humidifier producing heat - it only produced a fraction
of it's total power consumption as heat output. The heat coming off
the back of the unit is just heat removed from the air (and moisture)
entering the front of the unit. The latent heat of
vaporization/condensation of the water removed is the only appreciable
"heat" produced. (971 BTU/lb) So for every US gallon of water removed,
aproxemately 8000 BTU.
If it takes 12 hours to remove a gallon, that is 672 btu/hr or less
than 200 watts.
On 7/4/2014 2:37 PM, email@example.com wrote:
I do "get" your point, I just don't agree with it.
I don't think that follows. Most of the power in an AC unit is in the
compressor which creates the cooling. Reducing the temperature of the
air is going to take the same total amount of cooling, so there is no
power saving in a smaller unit. They size units to keep the initial
costs down and to provide enough cooling for the warmest days.
Your conclusions simply don't follow your premise. Unless there is
something less effective about the condensation of water in the large
unit it will end up collecting the same amount of moisture from the air.
But in reality there is an effect that makes the larger unit work
better. If the airflow over the coils does not cool the air below the
dew point, no water condenses at all. A sufficiently small unit with an
adequate air flow may well not lower the air temperature enough to
extract enough water during the process.
Again, no substantiation, just a claim. Running the small dehumidifier
removes small amounts of water AND warms the room requiring the AC to
run. Running the large AC unit will remove the water more quickly. If
it does not remove enough water heat must be added as it runs to remove
enough humidity (becoming a dehumidfier). The question is which unit is
more efficient as a dehumidifier and talking about "big-assed" ACs does
not answer the question. You are coming up with an answer based on an
emotional analysis of inadequate data.
The one fact I know is that my AC unit produces enough water to require
a pump to remove it and runs repeatedly all day. A dehumidifier I have
used will fill the two gallon bucket in a day or so in the worst humid
days of summer in the DC area. Still not sufficient data to prove one
or the other since I have never measured the output. But the AC only
cycles on and off while the dehumidifier runs continuously 24/7 until
the bucket is full.
You still fail to understand that is *exactly* what you are doing with
the dehumidifier. It had a hot coil and a cold coil. The hot coil
produces all the heat entering the cold coil plus the electrical energy
coming from the outlet. So you actually warm the room with that unit
requiring the AC to turn on even if it is otherwise not needed.
I'm not sure what you mean by the fraction comment. ALL electrical
energy consumed by this unit ends up as heat, mostly at the hot coil.
The condensed water has had its heat removed and then put back into the
air on the hot side of the unit. The question is where does that heat
go? Only part of the heat at the hot coil was from cooling the air,
most of it was from condensing the water. With a dehumidifier the
entire latent heat of evaporation is returned to the room along with the
heat from the electrical power required to make it all work. This will
heat up the room. With an AC unit that heat is exhausted outside
reducing your cooling costs. Don't think the latent heat of evaporation
needs to be returned to the room to maintain a temperature. When water
evaporates it cools. When it condenses it releases that heat and will
warm the room.
I guess one difference is that we have few days when we need
dehumidification but not cooling. If you actually need your space
warmed with dehumidification rather than cooled, then the dehumidifier
might be more efficient. But if you don't need the extra heat the AC
unit will have to run to maintain a temperature.
Trust, but verify is how I operate. That usually means figuring out
how things work before making a judgment. I'm not sure I'm ready to
accept your observations quite yet. Color me undecided.
Ok, that makes sense for AZ. However, they still specify a presumably
reflective light color, not a dark black asphalt surface that would
The US Dept of Energy version:
<http://energy.gov/energysaver/articles/cool-roofs> <http://web.ornl.gov/sci/roofs+walls/facts/CoolCalcEnergy.htm >Yes direct sunlight onto a surface is reflected or absorbed, but walls are
It's not the radiation into the night sky. It's the lack of clouds to
trap the hot air between the ground and the cloud layer that makes a
clear night sky rather cold.
Not quite. White is worn outside in the summer, with gray or black in
the winter. While dark clothes do get hotter on the surface, they are
somewhat cooler on the inside. The clothes are worn loosely where the
vertical temperature differential sets up a convective vertical air
flow. The inner layer traps much of the sweat against the skin, which
is cooled by the convective air flow. Much of the sweat remains
trapped against the skin, thus reducing overall water loss. The outer
layers provide air pockets, which offer some insulation value. If the
clothes are worn tightly, it doesn't work. Dark clothes also loose
heat faster than light clothes and are therefore worn indoors.
<http://www.traderscity.com/abcg/pic1.htm >so thought I'd give it
I do much the same thing. At night, I leave the house partly open so
that it cools down. In the morning, I close all the doors and windows
to trap in the cold air. At about noon, the house warms up to the
same as outside temperature, so I open with windows.
Jeff Liebermann firstname.lastname@example.org
150 Felker St #D http://www.LearnByDestroying.com
I like to do the same thing when we have cool nights like tonight. More
important than cooling the air in the house is cooling the house itself.
Air heats and cools quickly, the materials of the house, not so much.
So let the house cool as much as possible then shut the house when the
temperatures start to rise. I can't remember the house ever reaching
the outside temperature by noon, the equal point is usually in the
evening when the outside starts to cool again.
On Friday, July 4, 2014 2:54:16 PM UTC-4, dadiOH wrote:
I'm with you and Cl on this one. The physics of every AC says that when
you cool humid air, water condenses out. That water either has to go
out a drain line, dribble out, or else get deliberately put back into the
air, by reheating it somehow, like a hot pan. In the case of a residential
heat pump system, it would almost certainly be a drain line.
A make and model of the heat pump would settle it or perhaps a pic.
I didn't say they didn't have them, I said they weren't popular or commonly
available. That is true. Hell, I had to buy my first ones - Hunters - from
a company called "Fly Fan"...their customers were butchers and vendors in
open markets that bought them to shoo away flies.
I got two fans from an old guy in the 70's and at that point the fans
were already really old. Judging by the (largely absent) electrical
safety measures pre-WW2 but certainly consumer-grade. I ended up
throwing them away because the plastic in the blades looked like an
imminent failure waiting to happen. Don't remember what it was
(bakelite?). With a large fan the results of a failure could be nasty.
It looked cool though.
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