I am trying to install a new digital thermostat to an existing RUDD system. The original RUDD thermostat is currently installed. How do I find out how to install the thermstat? The wiring diagrams do not match the wires I have installed. And how do I find out what type of system I have for air conditioning? Thanks. Paul

Usually there is a 24 volt AC transformer in the furnace with the secondary winding connected to a red wire running to the thermostat and a blue wire to the gas valve, A/C relay, and fan relay. From the thermostat there will be white wire to the gas valve, yellow to the A/C, and green to the fan. The thermostat is wired to switch the power from the red to the white, yellow, and green as needed with the blue completing the circuit. It may be wired to have the control wires return to the furnace and its controls and then a second wire goes to the A/C unit. Internal wiring may replace the green wire if the thermostat does not give you the option of fan only or continuous fan.

The new thermostat may have a RC terminal the old one didn't. Usually it is jumpered to the R terminal, red wire. It may also have a terminal marked B or C. There will also be a terminal at the furnace marked B or C. Connect them using a blue or black wire if there is one in the cable.

As long as the air conditioner has an outside unit controlled by a relay, it doesn't much difference what kind it is. It needs to have a pair of wires running from the Y and the B or C terminals at the furnace, out to the relay coil.

You may have W1, W2,. at the furnace or thermostat making provision for different heating rates. Unless you can figure out something different from the installation manual, try connecting the white wire to W1.

Labman,
That is exactly right. I am trying to figure where I need to hook the W2 X amd E. E and W2 are umpered so I figured that was my power. Wrong the red is. This is where I got the mix up. The new thermostat has RH RC jumpered and E and W2 jumpered. I have a RUDD system with the thermostat. I have a DICO Thermostat I am trying to install.as long as I get the power right and follow the instructions to the typical 5 wire installation? I thank you for the help.
Paul
I tried to upload pictures of each thermostat but they are too large. If you would like to see them I can send them any way you would like. Thanks again.