Replace honeywell chronothorn 4 with nest thermostat

[shubham10008]

Hi All,

I am planning to replace my Honeywell Chronothorn 4 thermostat with Nest thermostat. 

I am not sure about wiring as my thermostat have wire in A and B, Is this same as W and R? 

Is nest compatible with this wiring?

Any help is highly appreciated.

[Patrick_Caezza]

No, That is a propitary interface that is not compatible with any Nest thermostat.