wire labels
if your existing
thermostat is marked...
RH / R / VR / 4
24 Volt
label the wire with this sticker:
RH
RH
RC / VC
24 Volt cool
Y / C* / M / O air conditioning 
compressor
RC RC Y/0
Y/0
W / H / B
heating
W/B
W/B
G / F
| fan | |
Y1 | heat pump | |
compressor | ||
|
G G Y1
Y1
10