My 1910 home has some 15 hot water radiators on three floors with a single boiler in the basement and one thermostat centrally located on the first floor. The system is well maintained and air-bled before each heating season. On a really cold day here in Buffalo, NY, there can be more than 10 degrees difference in temperatures from room to room. I am sure this is a common problem many owners of older homes face. I would like to find a high-tech method to effectively zone each radiatorís area. Is there a way to add wall-mounted programmable thermostats near each radiator to send information to motorized radiator flow valves (does something like this even exist?) that would prevent the warmer rooms from overheating while giving the colder rooms a chance to reach a comfortable temperature? Even at a couple-hundred dollars a radiator, this would be far less expensive that replacing an entire heating system in a 5000 sq foot home.