Heating Cooling Units

Help with installing a programmable thermostat?

I bought a Honeywell thermostat RHT7400 and I can not find how to install it. We have an old gas furnace (Original in 1986) and when I pulled the old manual thermostat, it was only Son 2, dark gray and white, and the instructions are for a 5 son. Any ideas on how I would install the new thermostat?

Need know the type of system you have. TRADELINE oven for wiring is: V c r-24 joint V-24 (if necessary) y w-g heat-cool fan

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