I've always wondered if a dehumidifier is more efficient than a window
air conditioner. If it were, I could get part of the comfort of what
the air conditioner provides, for less cost. My guess is that there is
minimal difference - isn't the dehumidifier doing the same cooling as
an air conditioner in order to condense the water out of the room air?
Appears the difference is that the dehumidfier just dumps the heat
back into the room instead of outside. (Of course, the dehumidifer is
better when the weather is damp but not too hot.)
More efficient at what?
The dehumidifier is more efficient at removing moisture. However it has
a side effect. It heats the air. It does not cool it or even leave it the
So if you are hot, run the AC if you just want to drop the humidity, and
you don't mind it a little hotter, like during winter, then run the
Ok, I'll bite:
Why is the dehumidifier more efficient at removing moistrue?
Don't both appliances use the same refridgeration cycle
The dehumidifier heats the air: Is this additional heat just the heat
generated by the motor and other moving parts of the dehumidifier, or
is there something about how it actually dehumidifies the air that
creates heat? (Obviously, the machinery of the air conditioner are
outside, so any heat from the motor, etc. stay outside.)
Well that statement of mine is not always 100% correct since there are a
number of things that go into efficiency.
In any case the dehumidifier cools the air when the air passes over the
evaporator coils and the moisture condenses. Then it directs that now cool
air over the condenser coils (the part that is usually outside) The
condenser coils now have cool air going across them so it works less. It
also only needs to move the air once, not once outside and once inside.
The dehumidifier like an AC removes heat from the air, it then returns
that heat to the same room so there is no loss there. However it is
consuming energy and every bit of electrical energy consumed ends up as
additional heat. In an AC much of that electrical energy ends up outside
with the compressor, but the humidifier has the compressor inside.
Also, the dehumidifier releases as much heat as boiling the water
produced would take.
This can be handy if you are living in a humid cold climate, the
electricity consumed can produce 2 or 3 times the amount of heat as
it uses with power.
Can't believe I missed the "phase change" as a source of heat, since I
have plenty of experience with steam boilers!
Condensing water vapor to water works out to .32kilowatt hrs. or 1096
BTU per pint.
A dehumidifier is optimizied for dehumidification. And air
conditioner is not. A dehumidifier only works when it's cool and damp
is it's rated to work in cooler temperatures (i.e. - Basement
Dehumidifier that operated below 65 degrees).
Sad to say not all are. I had one and even showed it installed in what
appeared to be a basement. However buried deep in the instructions was a
noted about the temperature or extra high humidity issue. It suggested
their special basement unit for those places. Sure and where do must people
In any case it turned out OK after three recalls and a number of phone
calls they modified it to work in cool areas. Now it works fine.
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