Rh & W wires mixed, 2 wire heating
Hope someone can help! Labman you've touched on this but I want to be sure.
I have a simple baseboard heater connected to an old analog thermostat with no labeling or HVAC color coding, and I would like to install a new programmable thermostat with only the Rh and W connected - I am using 2-wire heating only. (no fan, A/C, etc... ) .
There are two sets of wires in the electrical box behind the existing t-stat: 2 grounds, 2 white, 2 black. The two whites are connected to each other, and the two blacks are connected to 2 unmarked terminals on the old t-stat.
So here's what I need to know:
1. Do I leave the 2 whites connected, and connect the blacks to the R & W?
2. Does it matter which black goes to the R and which goes to W? (If so how can I distinguish between the two black wires?! )
Thanks very much!
Mark