I would get different thermostat and see if that resolves the issue. I have used the Honeywell RTH-6500 series and worked very well for my system. The Honeywell Visionpro 8000 can be purchased through amazon.com http://www.amazon.com/s/ref=nb_sb_ss...visionpro+8000
Now, if you really want something that you can track usage & costs, you could do like I did, and go with the Radiothermost 3m filtrate wifi thermostat. The better unit costs around $200-250, the one I got is around $100, and also works very well. The Visionpro series will allow you to use a outdoor sensor.