Hi


I bought a new thermostat a Honeywell rth7400 for heatpump & aux (oil as back up)

The old thermostat was a totaline with a separate toggle installed underneath it to switch back and forth from auxiliary to heat pump I have 8 wires coming out of the wall I have tagged them as followed: first group of wires W1, C, and a unmarked white unused
Second set of wires Aux (I am guessing it is the aux it was on the oil side of the toggle switch, R, G, Y1 and a unmarked black this wire was used with a doid of some sort with the toggle switch it seemed it was positioned in the middle. I don't think it was set up correctly the fan would always stay on even though the switch on the heating system was set to manual and thermostat fan option was not on. If anyone can help it would very much be appreciated

Thanks
Carnac

You have a very old dual fuel system setup with manual changeover. Usually this has to be done with ON SITE service since the wiring does not match any standard protocall. It can be time consuming and expensive.

Your best bet is to trace each wire (color and number or letter) and find out exactly where it lands in the system both indoors and out as done originally. This way you know exactly what is activating what control and what terminal and color was used on the old system to accomplish this. Make sure you identify and label each wire before you remove it from the old thermostat.Then make a legible wiring diagram of the old wiring and post it here to see if one of us can figure it out. No guarantee that we will be able to do that but I am sure we will try. Keepitsimplestupid loves this kind of stuff. LOL

Here is your new thermostat factory manual.

http://customer.honeywell.com/techli.../69-1900EF.pdf

Hey Hvac1000:

I resemble that remark! :D

Your welcome. LOL