Patent attributes
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. Condensation of flue gas products is prevented by monitoring flue exhaust temperature for each heater and controlling the modulation of each heater to maintain a minimum heater output sufficiently high to prevent condensation of flue gas products from that heater. Rapid reaction to changes in system heat demand is provided by sensing changes in flow rate in a primary loop of the system and anticipating resulting changes in temperature thus allowing for change in heater output prior to the time the change in flow rate has fully impacted system temperature.
