I'm trying to install a HoneyWell digital thermostat Pro 8000, part number TH8320U108 for my Rudd and Rheem heating and a/c system.

The Rudd Furnace is a plain Silhouette and the Rheem a/c is a model 3765SA17.

All of the wiring hook up points from the old Honeywell thermostat match the new one.
Except for the following. The new thermostat has a "RC" and a "R" hook up point with a jumper wire installed. But, the old one only has a "R" hook up point where the red wire was attached.

The installation booklet says if there is only one transformer, leave the jumper wire installed and hook the red wire to the "R" hookup point.
If there are two transformers, it says to remove the jumper wire.

How would I know if there are two transformers? If there are two transformers, is there another wire to be hooked up to the "RC" hookup point?

The honeywell customer service rep said he could not answer my questions. Because, only a professional electrician is supposed to install the Pro 8000.

A professional electrician? Sounds like the guy you talked to just didn't want to do his job or just plain didn't know. I have installed several of those and I am just a dumb 'ole HVAC/R guy lol.

Very rarely have I ever seen a residential split system with 2 transformers. In fact I can't ever remember one. But to be on the cautious side I: open up the electrical compartment on your furnace. There should be only one transformer there. If you have a second it is most likely in the electrical compartment of the condensing unit.

If the old thermostat worked with a red wire on R, then the new one will work with it connected to RH and RC.