Basic homeowner question here so be gentle...
I'm replacing the old murcury thermostat with a programmable digital to hopefully same some $$ on oil. It is a very basic system - oil fired boiler with baseboard heat; one zone; no A/C; no fans etc. The old (and I mean old) wiring is two wires, white & black. From what I can gather, one wire goes to the Rh terminal for "Heating power supply and one wire connects to W terminal for "Heating Signal". Questions is, does it matter which wire goes to which terminal?? The old thermostat has no markings in regards to what the wires or terminals represent so I can't copycat the instillation. My gut says white wire to Rh for power and black to W but I'd prefer not to have my gut destroy my $5000 boiler.