I have an Intertherm FEH-010HA-03 heater in my mobile home. It is a central heat/ac unit with a heat/cool switch on the heater. I need to replace the thermostat in the livingroom and it is a 2 wire thermostat. Is there a way to wire this system to a new Honeywell 7-Day Programmable Thermostat - RTH7600D, without using the heat/cool switch on the heater?

I have an Intertherm FEH-010HA-03 heater in my mobile home. It is a central heat/ac unit with a heat/cool switch on the heater. I need to replace the thermostat in the livingroom and it is a 2 wire thermostat. Is there a way to wire this system to a new Honeywell 7-Day Programmable Thermostat - RTH7600D, without using the heat/cool switch on the heater?

Yes there is but it is extremely complicated as the furnace controls contain relays and they will have to be changed or modified. Also depending upon weather or not you have a heat pump system or just plain A/C you will also have to run a minimum of 5 or 7 wire t-stat cable from the furnace to the wall where the thermostat is located. I have done these before and they are a pain for a professional let alone having a home owner do it. Sorry but it would be almost impossible to explain this unless I was there. If you really have to have that set up then I suggest you contact a ON SITE professional and have them do it for you.

No Heat Pump, just plain A/C. Can I hook it up easily and just use the Heat/Cool switch on the furnace?

The thermostat in your unit is a heat only thermostat that uses a relay system in the furnace to change the signal over to cooling. This is why you have a heat-off-cool selector switch on the furnace. You could try to wire your new thermostat for heat only I believe R and W terminals and still use the relays and switch on the furnace for change over purposes.The problem will be that the thermostat will not have constant 24 volt power to it and so it will have to run on battery's all the time which could get costly and a pain in the A$$ when it stops working at a time when you want it to lower or raise the temperature.

In other words I would not recommend using that RTH7600D thermostat unless you stripped the system controls,ran 5 wire cable to the thermostat location and then wire the system in a standard fashion. That is a bunch of work and that is why my vacation spot that has a mobile home on it still uses the old style thermostat and we switch it over for heat and cool just like yours works now. Since we do not use the camp year around and turn off the heat in the winter after we winterize the unit I just did not want to spend the time messing around changing it over for so little of a return on my end. I would rather be fishing instead.