We have 2 HVAC units with 2 thermostats (unit for front and back of house). The thermostats are located only about 8 feet apart and their sensitivity apparently varies by about 1/2 degree. If I set them both for 68, the one in the back always comes on to heat the house and the front one never comes on. If I set the front to 69 it will come on and the back one never will. I need to adjust one of them about half a degree if that is possible. They are Honeywell digitals (TH5220Ds).