I want to change out my old HW round manual T-stat for RLV430A. There are 4 wire coming out of the wall -red,yellow,white,yellow. The new one only has 2 black wires - I cannot figure out how to combine these. The unit is propane forced air. The directions for new one does not address my problem. Any advice?? Thanks

Youneed to go back to the furnace and see what wires are connected to the gas valve. You have heat only available... right?

It's Heating and Air - the duct work is there - it's like a natural gas pack only we live where there are no gas lines in area, so we have a buried tank for propane!
Thanks - Lee

Usually wires are color coded upon installation to make this a no-brainer. Since it wasn't done you need to find out where each wire goes before you can wire the new thermostat. Can't help you any further unless you pull all new wires.

Model # RLV430A thermostat is for an electric base board heater