The setback thermostat I presently have is one which can control central AC, but sadly, can't decide whether to heat or to cool. Sadly, they can only do one or the other. I have units like that at my wife's shop, and in rentals.

The option that the swamp-cooler provides that central air conditioning (AC) doesn't manage is the option of just ventilating rather than running the evaporator. Further, the swamp-cooler uses a blower-motor separate from the motor in the furnace. Now, I've considered plumbing the swamp-cooler into the furnace ductwork, but, as widely different in humidity as the air from the swamp-cooler is, than the air normally circulating in the furnace ductwork, makes me nervous. As dry as it normally is here in Colorado, the range is vastly different. When my hygrometer says 40% in mid-summer, it's as wet as it gets with the swamp-cooler running. When the thing's off, which is seldom between early June and late September, it's often down under 10%. Likewise, when the temperature outside drops into the far sub-freezing range, which is more and more seldom these days of global-warming, it's not unusual to the inside hygrometer to read well below 10%, and not uncommon for wooden furniture to suffer from shrinkage. There are doors in the house that don't function during the summer when the swamp-cooler is in frequent use because the shape of the door frame changes.

The reason I want internal and external temperature sensors is so I won't run the blower when it's warmer outdorrs than inside. If there's a small difference between indoors and out, and outdoors is lower, I'd consider running the blower without pump just to circulate fresh air.

Mainly, however, I want to shut off the water supply when the pump isn't running. That will prevent any more of those really LARGE water bills.

If I'm going to have to build something, I want ALL the features I can imagine. If I buy something, I just need most of them.

I'm still open to suggestions.

I still have a bandsaw, drill press, various saws and a jointer/planer and may go out and buy other stuff, but would like to minimize the "stuff" I have to find and subsequently put away.

RE