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In 1989, Canada Mortgage and Housing Corporation entered into a joint venture initiative to field est three diagnostic devices for oil fired heating equipment. These devices include:
- a Flame Quality Indicator
- a net peak stack temperature sensor
- an oxygen sensor
These devices have been under development by Brookhaven National Laboratories (BNL) for over two years and are intended to help improve efficiency, servicing and reliability of oil heating equipment. Diagnostic sensors can provide feedback to homeowners and service personnel regarding current state of burners so deviations from proper tune can be detected and corrected without prolonging the excessive fuel consumption.
Five furnaces in Ottawa, Canada were retrofitted with a prototype burner which contained a flame quality indicator (FQI). The FlameQuality Indicator (FQI) is an optical performance sensor that reads the light intensity from the burner flame and signals deviations from initial tune based on changes in flame brightness.
A net stack temperature was also installed in the flue of each furnace. As the furnace heat exchanger surface becomes fouled by the normal accumulation of soot, less heat can be extracted from the combustion gases. This results in an increase in net stack temperature. By monitoring the steady state or peak temperature over time, increases provide an indication of furnace fouling.
A Zirconium oxide oxygen sensor was also installed in one furnace. By monitoring oxygen content directly, deviations in burner performance from perfect tune can be detected.
Field trials were conducted for a period of one year (two heating seasons), the purpose of which was to assess the practicality of these diagnostic sensors in actual field applications. A comprehensive monitoring program was implemented to track data generated from the diagnostic devices and correlate the outputs against actual field measurements.
Generally, the FQI was observed to perform very well. At all sites the FQI signal was seen to track C02 content, and generate valid alerts when the C02 excursions were large enough, when the burners actually required service. Despite the fact that the FQI was able to effectively signal deviations in burner tune, and burner failures, the FQI requires further evaluation with regards to initial dulling, overheating and effects of fuel oil deliveries. An initial burn-in may be required for each burner fitted with an FQI device. The net stack temperature monitor does have the potential to signal heat exchanger fouling, but the high incidence of sensor failure suggest a more rugged sensor may be required. More field testing of this diagnostic strategy needs to be conducted.
While only sporadic data was collected for this the 02 sensor, both field and laboratory tests to date have indicated that it is too costly and difficult to implement correctly-for residential heating applications at this time.