Control system for modulating water heater

摘要

A control system is provided for a modulated heating system including a plurality of modulating water heaters, which may be modulating boilers. A deadband control scheme provides for reduced cycling of the modulating heater when total system heat demand falls between the maximum output of one heater and the sum of the maximum output of that one point and the minimum firing point of the next subsequent heater.

主权项

1. A water heating system comprising:
a water supply system; a plurality of water heaters connected to the water supply system for heating water for the water supply system; a water temperature sensor disposed in the water supply system; a temperature setpoint input for allowing a temperature setpoint for the water supply system to be selected; and a cascading control system operably associated with the plurality of heaters, the control system being configured to designate an operating sequence of the heaters, the control system being configured to define a combined operating range of the plurality of heaters including a deadband between a maximum output of one heater and the sum of said maximum output of said one heater plus a minimum output of the sequentially next heater, said control system being configured such that when a system heat demand falls within the deadband the control system maintains the output of said one heater at the maximum output of said one heater, and the control system allows the sensed water temperature to vary at least within a temperature range spanning the temperature setpoint before the sequentially next heater is turned on or off.