Old Thermo: Honeywell T8775A1009 New Thermo: Honeywell RTH6500WF Furnace: Honestly I do not know but I can find out, was told its like the Cadilac of furnaces, made in Italy. Oil Furnace, for hot water baseboard and hot water Everything was working fine, but I really wanted to be able to change the heat from anywhere in the house (only one thermo) or remotely, or view the temp. So I picked up the RTH6500WF. Took off my old thermo, discovered I only had 2 wires. R and W. Looked up some info, found out this would not work with the new one. Not sure why I even looked it up having known nothing about this topic LOL. Looked up more info, found out you can either run another C wire (which did not sound like fun, honestly not sure why at least a wire wasnt run with the rest as supposedly brand new 5 years ago). Can't do the G wire swap. Found some info that you can run a 24v transformer off a socket to it and work it that way. So I purchased a 24v transformer that you add your own wires too. Ran the wires needed from where the thermostat is to the plug. Hooked everything up. Swapped the socket while I was there just because. Tested the plus, worked. Checked voltages. Worked. Turned off power to the outlet, turned off the switch for the furnace. 2 hours later (was doing other things while I did this) and I had the new thermostat in. First tested that it would turn on, it did. Then turned back on the furnace and booted everything up. Works! Well... no. So I noticed that the furnace was kicking on every 10 minutes. Would stay on for 5 minutes, then turn off. 10 minutes later, back on for 5 minutes. Then off. Repeat. I thought maybe since the hotwater was off for so long, it needed to heat back up. But this went on for 2 hours. And it jacked the heat up to 78 degrees. So I pulled the thermostat off. waited 30 minutes. Furnace never came on unless we used the hotwater. Read the manual some more. Figured out that on the old thermostat it had some switches to set it to a 90% Eff Setup. So I checked the new one, it is not set that way and so I set it that way. Same issue. Going to hook up the old one again now. Any thoughts?

I recently replaced an old mercury-switch RUUD Q674L-1504 thermostat with a Honeywell RTH6580WF but it doesn't seem to be working properly. I'm getting cold air when the heat should be on. My system is an RUUD AC/Heat Pump with a aux heat provided by an oil furnace. Here is the wiring for the old thermostat. [ATTACH]40978[/ATTACH] I was told by Honeywell to wire the new thermostat as follows: Y to Y G to G E to Aux/E R to R/RC W2 to W2 X to C O to O/B B - Not Used Having read more about the O & B wires in a Heat Pump system it seems that you need both to tell the unit if the reverse valve should produce heat (B) or cool (O). So if the new thermostat doesn't use B, how does the Heat Pump know to throw the reverse valve into the heat position? Here is the wiring terminal for the Honeywell RTH6580WF thermostat: [ATTACH]40979[/ATTACH] The white wire is not hooked up and it was not hooked up on the old thermostat. Please help, we woke up freezing last night as the temperature dropped into the 40s and the AC kicked on instead of the heat. Thx......Arthur