Warm air furnace baselining and diagnostic enhancements using rewritable non-volatile memory

Abstract

A warm-air furnace is adapted to provide diagnostic enhancements and more robust installation. In an embodiment, sensing equipment aboard the furnace is used to determine a first performance metric during installation of the furnace. That performance metric is then compared with a baseline metric that may have been obtained at a factory in order to obtain a performance variation value. At least partially in response to the performance variation, a notification is provided to a user. The notification may be an indication of poor installation or shipping damage, present failure and/or predicted future failure, for instance.

1 . A method for warm air furnace diagnostics comprising: 
 determining a first metric of performance of the furnace at a first time;    comparing the first metric of performance with a baseline metric, whereby a performance variation value is obtained; and    at least partially in response to the performance variation, providing a notification to a user.    
   
   
       2 . The method of  claim 1 , wherein the first time is at installation of the warm air furnace at a customer premises.  
   
   
       3 . The method of  claim 1 , further comprising: 
 obtaining the baseline metric prior to shipping the warm air furnace from its manufacturing facility.    
   
   
       4 . The method of  claim 1 , wherein the baseline metric is a set of at least one recommended operational value for a model furnace of the same type as the furnace.  
   
   
       5 . The method of  claim 1 , wherein determining a first metric of performance comprises: 
 initiating a predetermined furnace test cycle;    at a predetermined portion in the test cycle, obtaining a measure; and    storing the first metric in a data storage of the warm air furnace;.    
   
   
       6 . The method of  claim 1 , further comprising: 
 storing the first metric in a data storage of the warm air furnace.    
   
   
       7 . The method of  claim 6 , wherein the data storage is a non-volatile memory.  
   
   
       8 . The method of  claim 1 , wherein the first metric is a set of at least one measure selected from the group of flame current, inducer current, fan current, pressure switch open time, pressure switch close time, heat exchanger rate of temperature rise, air temperature rise across the heat exchanger, furnace temperature, heating run-time, cooling run-time, fan-only run-time, igniter run-time, pressure switch cycle count, heating cycle count, cooling cycle count, fan-only cycle count, and igniter cycle count.  
   
   
       9 . The method of  claim 1 , further comprising: 
 determining that the variation is outside of a predetermined range; and    determining that the warm air furnace is not properly installed.    
   
   
       10 . The method of  claim 1 , further comprising determining the baseline metric at a second time, wherein the second time is after beginning installation of the furnace at a customer premises, and wherein the first time is subsequent to the second time.  
   
   
       11 . The method of  claim 1 , further comprising: 
 at the first time, determining a value for an operational counter of the warm air furnace, wherein the notification is at least partially based on the value of the operational counter.    
   
   
       12 . The method of  claim 11 , wherein the operational counter is one of a run-time counter and a cycle counter.  
   
   
       13 . The method of  claim 1 , further comprising, in response to the comparison, diagnosing a fault condition.  
   
   
       14 . A warm air furnace with diagnostics comprising: 
 a data storage for storing furnace performance data, wherein the furnace performance data includes a baseline measure and a first metric;    a processor communicatively couple with the data storage;    a set of instructions stored in the data storage and executable by the processor, wherein the set of instructions provide for (i) comparing the first metric with the baseline metric, and (ii) storing furnace performance data in the rewritable data storage; and    sensing circuitry for obtaining furnace performance data during operation of the warm air furnace, wherein the sensing circuitry is communicatively coupled with the processor.    
   
   
       15 . The warm air furnace with diagnostics of  claim 14 , wherein the first metric is a combination of at least one measure selected from the group consisting of flame current, inducer current, fan current, pressure switch open time, pressure switch close time, heat exchanger rate of temperature rise, temperature change across the heat exchanger, heating run-time, cooling run-time, fan-only run-time, igniter run-time, pressure switch cycle count, heating cycle count, cooling cycle count, fan-only cycle count, and igniter cycle count.  
   
   
       16 . The warm air furnace of  claim 14 , wherein the sensing circuitry comprises: 
 a current sensing device operable to measure current consumption of the warm air furnace, wherein the measured current consumption of the warm air furnace depends in part on whether an ignition element, an inducer, and a fan are activated; and    an analog to digital converter connected to an output of the current sensing circuit, wherein the analog to digital converter is operable to convert the output of the current sensing circuit to a digital representation of the measured current consumption, and wherein the processor is operable to compare the digital representation of the measured current consumption of the warm air furnace with the baseline measure that is stored in data storage, wherein the processor is operable to (i) detect a fault in the warm air furnace if the comparison exceeds a threshold amount, (ii) provide an indication of the fault, and (iii) identify at least one component in the warm air furnace that may have caused the fault.    
   
   
       17 . The system of  claim 16 , wherein the current sensing device includes a current transformer operable to provide an AC signal output representative of current consumption.  
   
   
       18 . The system of  claim 14 , wherein the data storage is at least one storage medium selected from the group consisting of read-only data storage, read-access data storage, electrically erasable programmable read-only memory, and Flash memory.  
   
   
       19 . A method for detecting a fault in a warm air furnace, comprising in combination: 
 measuring a level of current consumption during at least one operational stage of the warm air furnace wherein the level of current consumption of the warm air furnace depends on whether an ignition element, an inducer, and a fan are activated;    determining a performance variation between the measured level of current consumption and a previously measured value of current consumption for the at least one operational stage; and    detecting a fault in the warm air furnace if the performance variation exceeds a threshold amount.    
   
   
       20 . The method of  claim 19 , further comprising identifying at least one component in the warm air furnace most likely to have caused the fault.  
   
   
       21 . The method of  claim 19 , wherein the at least one operational stage of the warm air furnace is selected from the group of modes consisting of Idle, Inducer Start, Inducer Run, Ignition Element On, Fan Start, and Fan Run.  
   
   
       22 . The method of  claim 19 , further comprising identifying at least one component within the warm air furnace most likely to have caused the fault.  
   
   
       23 . A method of maintaining a furnace comprising: 
 determining a first set of performance values for the furnace at a first time;    recording the first set of performance values in a data storage of an electronic control device of the furnace;    comparing the first set of performance values to a historic set of performance values for the furnace; and    in response to a result of the comparing step, predicting a future fault of an element of the furnace.