I am trying to replace a White Rodgers 1E35-910 thermostat with a Honeywell RTH230B. Three wires, labeled W, R, and Y were connected to terminals 4, 5, and 6, respectively on the old thermostat. I have a baseboard hot water heating system. Connecting 4&5 opens the zone valve (White Rodgers 1311-103) and connecting 5&6 closes the zone valve. The Honeywell instructions are unclear about how to properly configure and wire the thermostat. Does the RcRh jumper need to be in place or removed? What wires go into which terminal? Thanks for the help.

I think you better reconsider the thermostat you are trying to use.

White Rodgers suggests this for a set back type

http://www.white-rodgers.com/wrdhom/pdfs/instruction_sheets/0037-6814.pdf

OR this for standard manual control.

http://www.white-rodgers.com/wrdhom/pdfs/06_Cat_pages/Cat_06_pg0020.pdf

1E30-910

3 wire style takes a special stat as far as I know.

Read under introduction
2 wire hot water systems

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