https://www.googlenestcommunity.com/t5/Nest-Thermostats/Google-Nest-thermostat-compatibility-with-our-heating-and-wiring-system/m-p/181018#M36814 <P>We have a boiler, hot water heating system with cast iron radiators (older home). Current thermostat has three wire connections RH, RC, and W (RH and RC are wired together). What Nest will work without additional wiring? &nbsp; &nbsp;</P> Mon, 13 Jun 2022 20:53:16 GMT Nancy3 2022-06-13T20:53:16Z https://www.googlenestcommunity.com/t5/Nest-Thermostats/Google-Nest-thermostat-compatibility-with-our-heating-and-wiring-system/m-p/181018#M36814 <P>We have a boiler, hot water heating system with cast iron radiators (older home). Current thermostat has three wire connections RH, RC, and W (RH and RC are wired together). What Nest will work without additional wiring? &nbsp; &nbsp;</P> Mon, 13 Jun 2022 20:53:16 GMT https://www.googlenestcommunity.com/t5/Nest-Thermostats/Google-Nest-thermostat-compatibility-with-our-heating-and-wiring-system/m-p/181018#M36814 Nancy3 2022-06-13T20:53:16Z