Re: really quiet central AC/dehumidifier?

Noon-Air writes: 
I wrote: 
>> I don't believe a central AC could keep the humidity below 50% in the
>> spring and fall, without me having to run the AC and heater, or
>> maybe the AC and dehumidifier, at the same time.

> It will if the system is correctly sized and properly installed.

That's what I don't understand!  What if it's too cold to run the AC, 
yet warm enough so the heater isn't drying the air much?  Say it's 
60F, and the humidity without any AC is 70%.  I would want to heat at 
that temperature, not cooling!  If you run the AC, won't it have 
to be cooling things down to 55F?  

I looked at an HVAC forum and there were a lot of people who said 
their AC wasn't dehumidifying very much.  I suppose you'd tell me 
that they don't have systems that are optimized for dehumidifying.  
But I still don't understand, simply, what about when it's cold 
enough you'd want to use the *heat*, AND it's damp?

Laura