Page 153

NORA Oilheat Technicians Manual

Chapter 7 Combustion Chapter 7—Combustion 7-27 than the reading at the breech, you have air leaks into the heat exchanger. Because of leakage, air has been pulled into the heat exchanger passages by the negative draft within the unit, lowering system efficiency. Keep a record of efficiency tests They have a saying in the nursing profession, “If you didn’t write it, you didn’t do it.” Why go to all the trouble of taking these tests if you don’t brag about it? Create or buy an efficiency test report form, and use it to record the results of your efficiency tests. These reports are important for three reasons: 1. They serve as a starting point for diagnosis and service. 2. Efficiency test results can be valuable sales tools when trying to convince customers to upgrade their equipment. 3. Having a written record can help protect you if there is ever a future problem. With most of the electronic combustion test equipment available today, a printer option is available. This gives you proof that you performed the test. Additionally, it provides time, date, and exact information as to burner performance when you left the unit. This can be invaluable when having to prove the burner operation at the time you made the adjustments. Typical Combustion Test Readings Non-flame retention burners: Oxygen: 5 - 9% Flame Retention Oxygen: 3 - 6% Carbon Dioxide: 10–12.5% Stack Temp: 60–79% Efficiency 400ºF to 600ºF Stack Temp: 80+ Efficiency 330ºF to 450ºF Stack Temp: 90+ Efficiency less than 125ºF Draft: -0.02"wc Over fire Draft (Stack): -.04"wc to -.06"wc Carbon Monoxide: Less than 50 ppm (diluted) Smoke spot: Zero to #1 Always Follow Manufacturer’s Specifications Report to the customer Your report to the customer can be written or oral. A properly written report, including a conservative estimate of savings you anticipate from any changes you have made or suggested, can build customer good will and increase equipment sales. Combustion air test Modern buildings are much tighter than the old buildings; some do not allow enough air to leak into the building from the outdoors to replace the air going up the chimney. Winterization practices on older homes have sealed many of the openings that formerly provided combustion air. If the building does not allow enough infiltration air in, provisions must be made to bring in the outdoor air to replace the air used in the combustion process. The following test will tell you if you have enough infiltration. 1. Visually inspect the venting system


NORA Oilheat Technicians Manual
To see the actual publication please follow the link above