Stack Temperature: With manual equipment, two holes will speed up testing and the thermometer should be placed into the unit on start and the rest of the testing done in the other hole when the temperature reading stabilizes. Draft: Do draft second because the other tests will be affected by any increase or decrease of draft. Smoke: To adjust for zero smoke number, you start by opening the burner air shutter or adjusting the head. Then Chapter 7 Combustion 7-12 Combustion Figure 7-10: Draft gauge Figure 7-12: Orsat tester Figure 7-13: Stack thermometer fine-tune the air to reach a zero smoke. CO2 or O2 : This is done last because if draft or smoke are wrong, it does not matter what CO2 is—you cannot leave the unit that way. Calculate Efficiency: Once the air is adjusted properly, take a final temperature reading, then compare the CO2 reading and the net stack temperature using the slide ruler to get the combustion efficiency of the unit. Important: Make a record of the results of each test on a Combustion Survey Form, which should show all before and after readings. Then you will know just how much improvement you are achieving. Figure 7-11: Smoke tester Step-by-step testing procedure The traditional order for taking these tests is: We also need a vacuum gauge to determine the condition of the oil delivery system. (See Chapter 4.) Steady state For accurate test results, measurements should be made after the unit has achieved steady state. Steady state is the point at which the stack temperature stops rising. At steady state there are no changes in the combustion gases, the unit has thoroughly warmed-up and will maintain constant conditions as long as the burner runs. This will require you to run the unit for 5 to 10 minutes, until the stack temperature reaches its highest point and levels off. Stack temperature The stack (flue gas) temperature is the temperature of the combustion gases leaving the appliance, and reflects the energy that did not transfer from the fuel to the heat exchanger. The lower the stack temperature, Manual combustion test equipment To successfully adjust oilburners with the manual equipment, we need the following: 1. To test for draft, we need a draft gauge. (Figure 7-10). 2. To test for smoke, we need a smoke tester and a smoke scale. (Figure 7-11). 3. To test carbon dioxide (CO2) we need an Orsat tester. (Figure 7-12). 4. A stack thermometer is used to measure the temperature of the flue gases. (Figure 7-13). 5. We need the combustion efficiency slide ruler to calculate efficiency. While not needed to calculate efficiency, it is important to know if the oil pressure to the nozzle is correct, and to measure this we need a pressure gauge capable of reading up to at least 300 pounds pressure.
NORA Oilheat Technicians Manual
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