I need to install a whole house swamp cooler setup. House is about 1800 sq ft. There are 3 bedrooms, a kitchen, and then a large family/living/dining room that is all fairly open to one another. There are 2 baths and a small laundry room that i could include but Im not sure if it is necesary.

What size unit should I install and what size ducking should use. I know ducting depends on room size and distense. Is there a formula to figure out the sizes neccesary? Ive been serching the web and havnt found much on the design of the system.