But I have a little issue. I installed a new furnace in the addition thinking the old furnace will not keep up with the added square footage. And I added some horsepower just to be safe. Now the 2 furnaces are "fighting" each other. The one heats the "old house and basement" and the other the "addition and crawlspace". Both the thermostats are on the main floor, at opposite ends of the house. But it seems they are sensing the heat from one another. So if the one in the "addition" kicks in, it heats up the whole main floor, and the "old" furnace does not kick in and leaves the basement cold. When the "old" furnace kicks in it heats the main floor and basement, but leaves the crawlspace cold. It is impossible to rewire the whole lot. I would have to somehow install a wireless remote thermostat in either the basement or crawlspace and eliminate one of the thermostats on the main floor.