Boiler control system and method

Abstract

The invention provides a boiler control system based on delayed cycle control, in which the control is implemented by interrupting a heating device enable signal (such as a BMS enable signal). This means the system can be used with electronic boilers without the boiler being aware (in terms of generating error codes) of the control taking place.

1 . A boiler control system for controlling a heating device in a boiler, comprising:
 a delayed cycle controller for activating and deactivating said heating device based on an upper temperature threshold and a lower temperature threshold;   a temperature sensor for measuring a boiler temperature;   an interrupt unit for interrupting a heating device enable signal thereby to implement the delayed cycle control of the delayed cycle controller, wherein the heating device enable signal is a signal externally input to the boiler which takes priority over an internal thermostatic control of the heating device in the boiler.   
     
     
         2 . A system as claimed in  claim 1 , wherein the interrupt unit comprises a relay switch. 
     
     
         3 . A system as claimed in  claim 1 , wherein the delayed cycle controller is adapted to set the lower temperature threshold based on temperature measurements. 
     
     
         4 . A system as claimed in  claim 1 , wherein the heating device enable signal comprises a building management system burner enable signal. 
     
     
         5 . A method of controlling a boiler heating device, comprising:
 sensing a boiler temperature;   activating and deactivating said heating device based on an upper temperature threshold and a lower temperature threshold to provide delayed cycle control, wherein the upper temperature threshold and lower temperature thresholds are below the internal upper and lower thermostat control settings of the boiler, such that the internal upper thermostat control setting is not reached;   
       interrupting a heating device enable signal thereby to implement the delayed cycle control. 
     
     
         6 . A method as claimed in  claim 5 , comprising performing a calibration operation to determine the upper temperature threshold. 
     
     
         7 . A method as claimed in  claim 6 , wherein the calibration operation further comprises measuring a cooling time between pre-calibration internal upper and lower thermostat control settings. 
     
     
         8 . A method as claimed in  claim 6 , wherein the upper temperature threshold is set equal to the pre-calibration internal upper temperature threshold, and after the calibration the internal upper temperature threshold is increased. 
     
     
         9 . A method as claimed in  claim 8 , wherein after the calibration the internal pre-calibration lower temperature threshold is increased. 
     
     
         10 . A method as claimed in  claim 6 , wherein the upper temperature threshold is set below the pre-calibration internal upper temperature threshold. 
     
     
         11 . A method as claimed in  claim 10 , wherein the lower temperature threshold is set below the pre-calibration internal lower temperature threshold. 
     
     
         12 . A method as claimed in  claim 5 , wherein the lower temperature threshold is controlled dynamically. 
     
     
         13 . A method as claimed in  claim 12 , wherein the lower temperature threshold is set to one of a fixed set of temperatures. 
     
     
         14 . A method as claimed in  claim 12 , wherein the lower temperature threshold is selected based on a temperature measurement at a fixed point in time after the upper temperature threshold is reached. 
     
     
         15 . A method as claimed in  claim 5 , wherein the heating device enable signal comprises a signal externally input to the boiler which takes priority over an internal thermostatic control of the heating device in the boiler, for example a building management system burner enable signal. 
     
     
         16 . A method as claimed in  claim 7 , wherein the upper temperature threshold is set equal to the pre-calibration internal upper temperature threshold, and after the calibration the internal upper temperature threshold is increased. 
     
     
         17 . A method as claimed in  claim 7 , wherein the upper temperature threshold is set below the pre-calibration internal upper temperature threshold. 
     
     
         18 . A method as claimed in  claim 13 , wherein the lower temperature threshold is selected based on a temperature measurement at a fixed point in time after the upper temperature threshold is reached.