Hitachi also offer a service to put most of there kit through an out of house specialist who treat the coils with anti-corrossive agents for special applications. If your going to do the install then maybe have a chat with Hitachi-tap them up for the company who treat the coils, and have this company undertake the same service to kit specifically designed for this environment-not room air conditioners as they'll never cope with the duty.

I worked on a few swimming pools last year. Fairly old kit R-22 based. Used the pool water to disipate condenser heat like a chilled water system only on the discharge side. The evaporator blasted through the ventilation ducts acting as a dehumidifier.

To be honest this was loads of grief. My advice........think carefully about taking the job on, and be sharp with your warranty terms or you'll never hear the end of it!

J