All installations and services must be performed by qualified service personnel.
replacement parts for location identification). After the furnace is warmed up to a steady- state condition (about 15 minutes), the final burner adjustment should be made using combustion instrumentation for measuring carbon dioxide (CO2) or oxygen (O2), carbon monoxide (CO), smoke (for oil furnaces), and stack temperature. In order to achieve the most efficient combustion possible, the following steps must be taken.
IMPORTANT: To achieve proper combustion and efficiency instruments must be used to secure CO2, O2 and CO readings.
1.CARBON DIOXIDE (CO2) or OXYGEN (O2): Take a CO2 sample from the flue pipe or vent connector at a position close to the furnace. It is possible to achieve relatively high CO2 (or low O2) readings with low stack temperatures to produce maximum combustion efficiency. However, the CO2 and O2 values recommended are slightly less, though this means slightly lower efficiency, to allow the burner to better tolerate adverse operating conditions, such as a cold heat exchanger, downdraft conditions, heating content changes in the fuel. This working tolerance means less service and maintenance during heating seasons as well as a reduced chance of producing carbon monoxide under adverse conditions.
2.CARBON MONOXIDE (CO): As described above, take a flue gas sample from the flue pipe or vent connector at a position close to the furnace. The amount of CO generated by combustion ideally should be zero or only a trace. In all cases, it must be less than 50 PPM. Carbon monoxide is a colorless and odorless gas, but it is toxic compound. The production of significant quantities of CO is a strong indicator of incomplete combustion. Check the fuel supply and the burner for fuel leakage. Check for an inadequate supply of clean air for combustion. Also, check for a restricted or blocked flue, vent, or chimney.
3.SMOKE: (oil burners only) A smoke sample should be drawn from the flue pipe or vent connector at a position close to the furnace. For the greatest efficiency, if the first smoke reading is “0”, close the air shutter on the burner until a trace smoke reading is obtained.
4.FLUE GAS TEMPERATURE: The flue gas temperature will vary to some degree depending on the heating content of the fuel, the amount of combustion air, and airflow across heat exchanger. In general, the lower the stack temperature, the higher the efficiency. However, stack temperatures under 350°F may cause flue gases to condense, which in turn may cause excessive metal corrosion.
5.TEMPERATURE RISE: Supply air temperature (measured twelve inches into trunk, away from radiant heat from the furnace) minus
Temperature rise = Supply air temperature - Return air temperature.
The temperature rise across the furnace heat exchanger operating at
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