I like,,,Found this on the Cornerstone Farms site....don't know if this is what he used or not....
http://www.cornerstone-farm.com/equipment/poultry-accessories-chicken/kool-bot

See

I only need it about 4 month out of the yr,,,
Here in Fairbanks Alaska...
I could just pump in cold air the other 8 months...
Hmmmm