I want the heater in the warm house to go on if the night temp drops below 60 and the day temp below 70. In the cool house the swamp cooler should be on if the temp reaches 75 during the day and I want it to knock the temp down to 55 during the night.

What is needed are programmable thermostats with 2 temperature ranges. For 110 volts that's a tall order, most are low voltage and need a converter and would not be suitable for the humid GH atmosphere. They exist but are expensive.

Since I'm on friendly terms with Rube Goldberg, designing a rig for the cool house got under way, a similar thing is possible for the warm one. Power comes from a power strip, one line goes to one of the thermostats which is set at 75F, it does not need a timer as I NEVER want the temp to be above 75F. Then there is a timer plugged into the power strip which activates at 10PM until 6AM and feeds power to the second thermostat which is set at 55F. These are inexpensive ($15)110V units which I protect from direct water.

Now it gets tricky. The 2 power cords emerging from the 2 thermostats are now spliced together. Black needs to go on black, white on white if your lines are color coded. Mine were not so I arbitrarily spliced them one way. Since there was only a 50% chance of being correct I brought a sacrificial lamb, a small desk lamp which was plugged in. As long as only one thermostat is active there never is a problem, if both are open, there is an overload if the colors are not matched correctly.

I turned both on and immediately blew the fuse of the power strip and the house fuse box. Obviously I had spliced the 2 power cords together wrong so I reversed that, reset the fuses and there has been no more problem. The Swamper works well if either or both of the thermostats are open.

An identical set up will work in the warm house. Cost is $34 for the timer and the 2 thermostats, a far cry from the cost of a 110V 2 zone unit. To understand it better, draw the flow chart of the lines, it is actually safe and works. As long as the power source is from the SAME power strip, it is impossible to inadvertently create 220V which would not be good. If you spliced incorrectly, all that happens is that the fuse blows, reverse the splicing and all is well.

Nick