A heating, ventilation and air conditioning capacity alert system

Abstract

A system for light commercial building solutions (LCBS). Solutions and other systems may incorporate lightweight alerting service, auto-adjustment of gateway poll rates based on the needs of various consuming applications, detecting loss of space comfort control in a heating, ventilation and air conditioning (HVAC) system, HVAC capacity loss alerting using relative degree days and accumulated stage run time with operational equivalency checks, and HVAC alerting for loss of heat or cool capacity using delta temperature and dependent system properties. Also, incorporated may be triggering s subset of analytics by automatically inferring HVAC equipment details from controller configuration details, ensuring reliability of analytics by retaining logical continuity of HVAC equipment operational data even when controllers and other parts of the system are replaced, and an LCBS gateway with workflow and mechanisms to associate to a contractor account.

What is claimed is: 
     
         1 . A heat exchanger capacity change detection system comprising:
 a first temperature detector situated at an air intake of a heat exchanger;   a second temperature detector situated at an air discharge of the heat exchanger; and   a processor connected to the first temperature detector and second temperature detector; and   wherein:   the first temperature detector provides an intake air temperature signal to the processor;   the second temperature detector provides a discharge air temperature signal to the processor;   the processor provides a delta temperature indication that is a difference between an intake air temperature and a discharge air temperature of the heat exchanger;   the processor provides a derivative of the delta temperature indication; and   the derivative of the delta temperature indication can indicate a steady state condition has been reached from system changes that affect a delta temperature provided that operational properties of the heat exchanger remain constant.   
     
     
         2 . The system of  claim 1 , wherein an intake air temperature and a discharge air temperature are dry bulb temperatures of air. 
     
     
         3 . The system of  claim 1 , wherein an operational property is one that can vary to change a capacity of the heat exchanger that does degrade a capacity of the heat exchanger. 
     
     
         4 . The system of  claim 1 , wherein the operational properties are at least one or more items selected from a group comprising a number of active stages, air flow rate, outdoor dry bulb temperature, mixed air wet bulb temperature, and mixed air dry bulb temperature. 
     
     
         5 . The system of  claim 1 , further comprising a change of capacity alert device connected to the processor. 
     
     
         6 . The system of  claim 5 , wherein:
 if the delta temperature indication is at least N percent different from an expected delta temperature, then the change of capacity alert device indicates that the heat exchanger has a change of capacity; and   N is a predetermined number.   
     
     
         7 . The system of  claim 5 , wherein the change of capacity alert device
 the derivative of the delta temperature is a value indicating delta temperature has reached steady state; and   the operational properties of the heating or cooling system that when changed can affect the delta temperature without a degradation of a capacity of the heating or cooling system, are kept constant.   
     
     
         8 . The system of  claim 7 , wherein the operational properties of the heating or cooling system that when changed can affect the delta temperature without a degradation of a capacity of the heating or cooling system are selected from the group consisting of cubic feet per minute, mixed air temperature, mixed air wet bulb temperature, outdoor temperature, delta temperature, and combinations thereof. 
     
     
         9 . The system of  claim 8 , wherein instances of occurrences of sets of operational properties of the heating and cooling system are stored as instances of a recorded reference. 
     
     
         10 . The system of  claim 9 , wherein if a value of a steady state delta temperature is the same as a previously recorded reference, then a change in capacity of the heating or cooling system is zero. 
     
     
         11 . The system of  claim 9 , wherein a value of a steady state delta temperature less than a previously recorded reference indicates a change in the capacity of the heating or cooling system. 
     
     
         12 . The system of  claim 9 , wherein if the capacity of the heating system has decreased according to the derivative of the delta temperature, then an amount of a decrease of capacity is determined by a magnitude of the value of the derivative of the delta temperature. 
     
     
         13 . The system of  claim 12 , wherein:
 if a decrease of capacity is at least X percent, then an alert is provided by the processor; and   X is a predetermined number.   
     
     
         14 . A method for determining a change of capacity of a heating or cooling system, comprising:
 determining a commanded capacity of the heating or cooling system that remains constant;   measuring a first temperature of an air input to the heating and cooling system;   measuring a second temperature of an air output of the heating or cooling system;   determining a delta temperature from a difference of the first temperature and the second temperature; and   calculating a derivative of the delta temperature; and   wherein:   if the derivative of the delta temperature is within D of zero, then the delta temperature has reached a steady state and is valid for capacity comparisons;   if delta temperature has decreased from a previously recorded value, then this decrease represents a loss of capacity; and   D is a predetermined number.   
     
     
         15 . The method of  claim 14 , wherein:
 the heating or cooling system has operational properties; and   the operational properties have parameter values that remain constant when the first and second temperatures are measured, and the delta temperature is determined from the first and second temperatures.   
     
     
         16 . The method of  claim 15 , wherein:
 the operational properties are at least one or more items selected from a group comprising a number of active stages, air flow rate, outdoor dry bulb temperature, mixed air wet bulb temperature, and mixed air dry bulb temperature; and   when the operational properties change, they can cause a change in capacity without degradation of capacity of the heating or cooling system.   
     
     
         17 . The method of  claim 14 , wherein detectors of the first temperature and the second temperature measure dry bulb temperatures of air. 
     
     
         18 . The method of  claim 14 , wherein N is a number. 
     
     
         19 . The method of  claim 14 , wherein:
 the measuring of a first temperature is achieved from a first sensor situated at the air input;   the measuring of a second temperature is achieved from a second sensor situated in the air output;   the determining the delta temperature is provided by a processor connected to the first sensor and the second sensor; and   the calculating the derivative of the delta temperature is with the processor.   
     
     
         20 . An alerting mechanism relative to a capacity change of a heating or cooling system, comprising:
 a first temperature sensor at an air input of a heat or cooling system;   a second temperature sensor at an air output of a heat or cooling system; and   a processor connected to the first temperature sensor and the second temperature sensor; and   wherein:   the processor determines a delta temperature between a first temperature indicated by the first temperature sensor and a second temperature indicated by the second temperature sensor;   the processor calculates a derivative of the delta temperature; and   a derivative of the delta temperature is calculated and is a value indicating delta temperature has reached steady state.