dehumidifier efficiency

[bill]

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.)

Thanks

[Joseph Meehan]

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 same.

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 dehumidifier.

[bill]

there is

However it has

humidity, and

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.)

[Childfree Scott]

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).

[Joseph Meehan]

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.

[Joseph Meehan]

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 use one?

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.

[Ian Stirling]

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.

[jriegle]

[jriegle]

Also, when water condenses, it gives up heat. This heat is also expelled into the room. John

[bill]

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.

[Joseph Meehan]

I was about to look that up myself in one of my old college physics books. I don't think it has changed in 40 years has it? ;-)