Thermostat wiring

[bknodel]

I have an existing thermostat with six wires, 5 of which are connected. It is low voltage and solid wiring. 

Connected are:

Brown

White

Yellow

Green

Blue

Not used:

Red

Is Nest Learning Thermostat compatible? I cannot read the post that Brown is connected to. 

Thanks

[laurentbourg]

Could you please post a picture of your current wiring as well as the details of your hvac setup (e.g heat pump, single stage electric etc). 

[bknodel]

I have a split system, updraft units,  20 year old Lennox, non heat pump. 3.5 ton and 4.0 ton units. 6 wires. I don’t have a photo but the wires are solid, brown (RC) white (W1) green (G) yellow (Y1) Blue (B) and red is spare. Low voltage controls. Hope that helps

[laurentbourg]

ok thank you, your system should be compatible. 

[bknodel]

Thanks for your help!!