AC vs dehumidifier

[songbird]

i see in the other thread that there is talk of running the AC to get rid of humidity, so i thought i'd bust this topic out into it's own thread...

is there any significant difference in cost between running a dehumidifier and the AC?

my guess is that in our case that the cost would be different, but the tradeoff against having another machine to maintain or purchase might make it not worth the bother for as little as we use it.

the cost would be different because when we run the AC two motors are running whereas if we had a separate dehumidifier only one would be running (and it might be a lot more efficient).

songbird

[trader_4]

It comes down to this. If you want heat removed from the space too, then AC is the way to go. If you want to maintain the temp then a dehumidifier is the solution. Actually, the dehumidifier will be adding some heat to the space from the electricity used to run it. If it's central AC, it will also be able to handle a large area, it's capacity is going to be many times that of a dehumidifier. The dehumidifier is most useful in my experience in places like a basement, where you don't want to lower the temperature but want to take out the humidity.

I think your motor count is off too. Central AC would have

3 motors: air handler, compressor, condenser fan. Dehumidifier would have two: compressor and blower. Wall AC unit, not sure if it's 2 or 3. But the number of motors really doesn't tell you anything of much use anyway.

[songbird]

trader_4 wrote: ...

our AC is part of the heating system so it has the outside unit and the inside blower motor. not sure where the compressor is and if that is a separate motor.

this house is fairly small and one level so it's pretty efficient to heat and cool, i just hate running the AC. in the future i hope to be able to get by with a small dehumidifier and a small fan instead of running the AC.

songbird

[Stormin Mormon]

First, that's pretty much what I would have said. Dehum is used in naturally cool spaces like cellars.

Wall or window AC typically have one fan motor, which has a blade on each end of the shaft.

In terms of energy efficiency, the big factors are type of compressor, and how clean are the coils.

[trader_4]

the outside unit has two motors, the compressor and the fan.

[songbird]

trader_4 wrote: ...

ah, ok, thanks! :)

a small unit that runs longer might be ok (say if you have solar panels that only put out a few kw/hr).

songbird

[clare]

The typical stand-alone dehumidifier also has 2 motors, but they are smaller. The units are also less effective, but are handy when you do not want to significantly cool the space while removing excess humidity.

It is humid enough here today to want to run the AC or dehumidifier, but cool enough that to get any dehumidification effect from the AC the house would become uncomfortably cold - so the portable dehumidifier is removong about 45 liters of water per day from the air in the house, maintaining about 40% RH without unduly cooling the house.

[dpb]

On 07/17/2015 3:40 PM, [e-mail] wrote: ...

And actually, they _warm_ the house slightly as both the waste heat from the compressor and the motors is exhausted into the living space...