A system for heating a building, including a heat generator to heat a carrier fluid, at least one radiating element for transferring heat to a thermal load included in a building, a delivery conduit for transferring the carrier fluid from the heat generator to the radiating element, a return conduit for transferring the carrier fluid from the radiating element to the heat generator, a three-way valve arranged along the delivery conduit and connected to the return conduit, the three-way valve being operable to mix the carrier fluid in the delivery conduit to the carrier fluid in the return conduit, a plurality of temperature sensors arranged to measure the temperature of the carrier fluid and a temperature of the environment outside the building, and a control unit operatively connected to the heat generator, to the three-way valve and to the temperature sensors.

A system for heating a building, including a heat generator to heat a carrier fluid, at least one radiating element for transferring heat to a thermal load included in a building, a delivery conduit for transferring the carrier fluid from the heat generator to the radiating element, a return conduit for transferring the carrier fluid from the radiating element to the heat generator, a three-way valve arranged along the delivery conduit and connected to the return conduit, the three-way valve being operable to mix the carrier fluid in the delivery conduit to the carrier fluid in the return conduit, a plurality of temperature sensors arranged to measure the temperature of the carrier fluid and a temperature of the environment outside the building, and a control unit operatively connected to the heat generator, to the three-way valve and to the temperature sensors.

An underfloor heating (UFH) system limits the floor temperature of an environmental entity (for example, a room) by pulsing (pulse modulating) the flow rate through a hydronic emitter (circuit) heating the environmental entity. Once the heated water fills the circuit during time interval T.sub.on, the flow is stopped for a fixed time T.sub.off before allowing the cycle to repeat until a target temperature is reached. The ratio of flow/no flow (T.sub.on/T.sub.off) may be a proportional lower floor temperature compared to a traditional circuit supporting a constant water flow. The UFH system may heat a plurality of rooms, each having different floor temperature limitations. The floor temperatures may be limited differently by pulsing the hydronic emitters (circuits) rooms differently.

A zone controller works with a modulating unit comprising memory storing an instruction set and data related to thermostats, a plurality of duty cycles for a plurality of zones, a plurality of time periods for the plurality of zones, and a maximum zone load. A processor is operative to provide a modulating signal to the modulating unit based on the maximum zone load. The modulating signal determines operation of the modulating boiler and the maximum zone load based on the plurality of duty cycles, time periods, and data related to thermostats. The zone controller may be further operative to: calculate a first duty cycle for the first zone based on a first time period; calculate a second duty cycle for the second zone based on a second time period; and determine a maximum zone load, which is a greater of the first duty cycle and the second duty cycle.

An underfloor heating (UFH) system limits the floor temperature of an environmental entity (for example, a room) by pulsing (pulse modulating) the flow rate through a hydronic emitter (circuit) heating the environmental entity. Once the heated water fills the circuit during time interval T.sub.on, the flow is stopped for a fixed time T.sub.off before allowing the cycle to repeat until a target temperature is reached. The ratio of flow/no flow (T.sub.on/T.sub.off) may be a proportional lower floor temperature compared to a traditional circuit supporting a constant water flow. The UFH system may heat a plurality of rooms, each having different floor temperature limitations. The floor temperatures may be limited differently by pulsing the hydronic emitters (circuits) rooms differently.

A zone controller works with a modulating unit comprising memory storing an instruction set and data related to thermostats, a plurality of duty cycles for a plurality of zones, a plurality of time periods for the plurality of zones, and a maximum zone load. A processor is operative to provide a modulating signal to the modulating unit based on the maximum zone load. The modulating signal determines operation of the modulating boiler and the maximum zone load based on the plurality of duty cycles, time periods, and data related to thermostats. The zone controller may be further operative to: calculate a first duty cycle for the first zone based on a first time period; calculate a second duty cycle for the second zone based on a second time period; and determine a maximum zone load, which is a greater of the first duty cycle and the second duty cycle.