Dehumidifiers??

[OakLeaf]

(a) Yes. A LOT.

(b) We've been using one so long I don't know how much it adds to the electric bill. But we had a flood in our basement a few years back that had to be dried out by running four industrial dehumidifiers 24 hours a day for I think a week. Each one of those was WAY WAY WAY more powerful than the kind of home unit you're talking about, they ran continuously rather than intermittently (oh man this is reminding me how loud and awful that was ) and it cost us about $20 compared to our electric bill for the same month in the prior year.

In warmer climates a humidistat on the AC is supposed to be more energy efficient than a standalone dehumidifier.

The electric bill is going to be cheaper than the amount of stuff he'd have to replace because of mold otherwise. I've lost too much stuff to mold, to ever go without a dehumidifier again.

(c) It depends on how big his apartment is and how well the air circulates. Definitely he'd need to leave closet doors open, maybe cabinet doors too. A circulating fan will help.

(d) For northern California, make sure he gets a unit that's designed for low temperature operation. Otherwise it will be prone to icing up. Icing isn't that big of a deal as long as the apartment is occupied and he can turn the thing off for a while and let it melt, and you do get a sense after a while of how low you can set the humidistat without icing, but it's kind of a PITA ... if the place will be unoccupied for days at a time, then icing can be a problem when the unit runs continuously without taking any humidity out of the air.


As far as your own condo - normally the reason AC won't reduce humidity is because the compressor is too big for the amount of area it's cooling, so it doesn't run long enough to dehumidify. I don't know where your AC is in its life cycle, but if it's nearing when you'd have to replace it anyway, make sure you tell the installer about your humidity problems and size the unit accordingly.