Purchased a nest to replace my old old themostat. I have wires G, RC, Y, W, and a 4. Site says the 4 means its priority and need to go through local supplier. Anyone know where 4 wire should connect to still use. Thanks
The Google Help page says that wires 1 - 4 are "proprietary", meaning that they are unique to a particular manufacturer, so you would either need to contact the manufacturer or a heating and cooling professional who is familiar with that manufacturer to determine the proprietary or unique purpose of your #4 wire and whether it can be rewired to be Nest compatible:
Perhaps if you posted the name of the manufacturer(s) of your heating and cooling systems, a reader in this forum might recognize your #4 wire in conjunction with that manufacturer.
