be adjusted based on the information that the boiler controller 20 receives from the outdoor air sensor 31 supply sensor 32 return sensor 33 or other appropriate sensors sources in some zoned systems a multi speed pump may be provided to vary the amount of water that is forced through the system depending on the number of calling zones for example the pump 50 may have two speeds and use a lower speed when only one zone is calling for heat and a higher speed when two or more zones are calling for heat referring to fig2 an illustrative control system 11 is shown diagrammatically the system includes a boiler controller 20 which controls at least one boiler 21 and separate zone controller panels 22 connected by a communication bus 24 the communication bus 24 allows two way communication between the zone panels 22 and the boiler controller 20 in the embodiment shown the communication bus 24 is one or more standard ethernet cables with standard connectors 26 such as but not limited to rj45 connectors and or splitters in the embodiment shown two 2 zone panels 22 are connected to the boiler controller 20 one zone panel has four 4 conventional thermostats 29 the other zone panel has three 3 conventional thermostats 29 and a configurable communicating thermostat 30 as discussed above the communicating thermostat 30 is u201c instanced u201d with an individual zone address both the zone panel 22 and boiler controller 20 read this address and the information programmed into the communicating thermostat while two zone panels 22 and eight thermostats 29 30 are shown other.