I am trying to install two setback thermostat and the wire designations don't seem to match. The first thermostat to gas heat and electric air Has:R, y/y2, C, G, W/W1. My new thermostat has RC, RH and they are linked, W, Y, and G. My guess is that I attache:
R to RH
C to RC and take out the link,
Y/Y2 to Y
W/W1 to W
G to G.

The second thermostat is to a heat pump and I believe some are self explanitory but others are not.

O/W2B to O
R to R
C to C
G to G
But then I have:
Y/Y2 on the old thermostat but the new one is missing Y2 but there is a Y1.
W/W1 on the old thermostat but the new one is missing W1 but has a W2 which also has a conecting wire to E.

Any suggestions.
Gordon