Modulation control of a hydronic heating system

Abstract

A hydronic heating system for a building includes condensing and non-condensing boilers in a hybrid arrangement. A control apparatus receives information from one or more condition sensors, such as air temperature or water flow, and calculates heating load requirements. The control apparatus then independently selects and operates the various boilers of the system to optimize boiler efficiency and operating characteristics. The independent operation of said first and second boilers is modulated as a function a comparison of a heat load assignment for the and second boilers to a heat output of the first and second boilers.

1 . A hydronic heating system comprising:
 at least a first boiler having first operating characteristics;   at least a second boiler having second operating characteristics;   at least one sensor measuring a condition and providing an output indicative of said measured condition; and   a controller, operably coupled to said first and second boilers, comprising:
 a processor, responsive to said sensor output, for calculating a heating load; and 
 a control, responsive to said calculated heating load, for independently operating said first and second boilers in a manner that matches said heating load to said first and second operating characteristics, wherein the independent operating of said first and second boilers is modulated as a function a comparison of a heat load assignment for said first and second boilers to a heat output of said first and second boilers. 
   
     
     
         2 . The hydronic heating system of  claim 1 , wherein said first boiler comprises a condensing boiler. 
     
     
         3 . The hydronic heating system of  claim 1 , wherein said second boiler comprises a non-condensing boiler. 
     
     
         4 . The hydronic heating system of  claim 1 , wherein said first operating characteristics comprises at least a first temperature reset slope. 
     
     
         5 . The hydronic heating system of  claim 4 , wherein said at least said first temperature reset slope is selectable by a user of said system. 
     
     
         6 . The hydronic heating system of  claim 1 , wherein said second operating characteristics comprises at least a second temperature reset slope. 
     
     
         7 . The hydronic heating system of  claim 6 , wherein said at least said second temperature reset slope is selectable by a user of said system. 
     
     
         8 . The hydronic heating system of  claim 1 , wherein said condition comprises outdoor air temperature. 
     
     
         9 . The hydronic heating system of  claim 1 , wherein said condition comprises indoor air temperature. 
     
     
         10 . The hydronic heating system of  claim 1 , wherein said condition comprises the temperature of water circulating through said system for at least one location. 
     
     
         11 . The hydronic heating system of  claim 1 , wherein said processor calculates a real-time heating load. 
     
     
         12 . The hydronic heating system of  claim 1 , wherein said control operates at least one of said first and second boilers to maintain a predetermined difference between the temperature of water entering said at least one boiler and the temperature of water exiting said at least one boiler. 
     
     
         13 . The hydronic heating system of  claim 1 , wherein said control operates at least one of said first and second boilers to maintain water circulating through said at least one boiler for a period of time following a time of operation of said boiler, said period of time being calculated as a percentage of said time of operation. 
     
     
         14 . The hydronic heating system of  claim 1 , wherein said control provides sequencing of said first and second boilers. 
     
     
         15 . The hydronic heating system of  claim 14 , wherein said sequencing is in response to the accumulated operating time of each of said boilers. 
     
     
         16 . The hydronic heating system of  claim 14 , wherein said sequencing is in response to the output capacity of each of said boilers. 
     
     
         17 . The hydronic heating system of  claim 9 , wherein said sequencing is in response to said first and second operating characteristics. 
     
     
         18 . The hydronic heating system of  claim 1 , further comprising means for measuring and adjusting the pH of water circulating through said system. 
     
     
         19 . A hydronic heating system comprising:
 a plurality of boilers having at least two different operating characteristics;   at least one sensor for measuring a condition and providing an output indicative of said measured condition; and   a control, operably coupled to said plurality of boilers, comprising:
 a processor, responsive to said sensor output, for calculating a heating load; and 
 a control, responsive to said calculated heating load, for independently operating each of said plurality of boilers in a manner that matches said heating load to said different operating characteristics, wherein the independent operating of said first and second boilers is modulated as a function a comparison of a heat load assignment for said first and second boilers to a heat output of said first and second boilers. 
   
     
     
         20 . A hydronic heating system comprising:
 a first boiler having first operating characteristics;   a second boiler having second operating characteristics;   a control, operably coupled to said first and second boilers, for determining a heating requirement in response to at least one condition and independently operating said first and second boilers to meet said heating requirement in accordance with said first and second operating characteristics, wherein the independent operating of said first and second boilers is modulated as a function a comparison of a heat load assignment for said first and second boilers to a heat output of said first and second boilers.