Just wondering if these are available in Bangkok. Had one in a house in the US, and it was great for cooling down a house at night.

Anyone know of a dealer/installer?

You need cool air in the evening for them to work well - most places in Thailand are not that cool and if not using air conditioning have all windows open so will have to close most of them if using such a system.

Am sure a handyman could rig up such a system using attic fans in your ceiling and know that such fans are available. But getting family to close windows might be more difficult.