I have a 3 wire zoned heating system, and trying to install the Honeywell RTH230B programmable thermostat. I removed an old Honey well thermostat and the terminals so old I couldn't make out the terminal identifiers. Currently I have 4 wires exposed in my wall Red Yellow Black Green. Can someone tell me where on the terminals for my thermostat I should be placing these wires.

Currently I have them set as follows

Red on RH Heating power supply
Jumper between RhRc Heating Power Supply and Cooling Power Supply
Green on G terminal Fan
Black on W terminal Heating signal

((I have a 3 wire zoned heating system)) ARE you talking about the number of wires on the zone valve? Because you stated you have 4 thermostat wires to start with.
If you have hot water heat with 3 wire zone valves the thermostat you have will not work.

For all other systems here is your manual.


http://customer.honeywell.com/techlit/pdf/69-0000s/69-1800.pdf

The instructions said to label/identify the wires on the old thermostat for placement on the new thermostat. Since you could not identify the terminals on the old thermostat it will be nothing but a guessing game from here. You will have to track down each wire from the thermostat to where they land in the furnace terminal strip then see where they go and what they operate from there, Then after you find out that you will be able to refer to the new thermostat wiring locations. Sorry but that is the reason for identifying the wires on the old thermostat.