A thermostat provides the control signal to a cooling/heating unit. If you don't have a thermostat in your home, the unit will not respond to temperature changes in the home. There are a few things you should determine before purchasing a thermostat. The most important is finding out what system you have and determining if your desired thermostat is compatible with your home … [Read more...] about Thermostats: Which Thermostat Do You Need?