I live in the humid south, where we're constantly fighting humidity levels in our house of above 60%. I'd love to keep my A/C at 28C/82F, but at those levels the humidity never drops to low enough levels for 1) our sanity, and 2) mold prevention.
I don't really understand much about whole house humidifiers. Do any of you use them? Are they worth installing? Are they easy to install myself, and if so, what are the gotchas?