National Oilheat Research Alliance 21 throughout a building. If a leak develops in a heat exchanger, carbon monoxide (CO) can enter into the heated air and pose a health and safety risk to the building’s occupants. There are a number of indications that a heat exchanger may be leaking, including: • A flame pattern change when the blower comes on; • A properly located CO alarm sounding; • Odors and/or soot in the home. There are numerous ways to test for heat exchanger leakage; among the most effective are: 1–A visual inspection 2–Measuring the CO in the return air and in the supply air. If the CO reading in the supply is higher than in the return, the heat exchanger may be defective and a through visual examination is required to search for cracks or other problems. 3–Measuring the steady state O2/CO reading at the breach before and after the blower comes on. If the O2 reading changes, or the CO reading increases by more than 10%, the heat exchanger may be defective. 4–An over-fire draft test. Measure the overfire draft while the burner is operating at steady state and the blower is off. Then energize the blower. If the draft changes, the heat exchanger may be defective and a thorough visual examination is required to search for cracks or other problems. Note: When using instruments to test for a defective heat exchanger, make sure that cleanout ports and gaskets are fully secured, all furnace access panels for air distribution are in place and that there is no leakage on the return side of the furnace. Ventilation Ventilation is necessary for maintaining acceptable indoor air quality and to minimize adverse health effects. Improved construction techniques continue to tighten new and existing homes requiring us to focus on indoor air quality. Tightening a house, eliminating leaks in the building envelope will reduce the number of times the building air changes. This will save energy and improve comfort by eliminating drafts. Proper sizing and controlling of the ventilation system is crucial for ensuring pollutants do not enter the occupied space and maintaining the right level of humidity. A home can quickly become depressurized from the operation of a clothes dryer, central vacuum, kitchen and bathroom exhaust without proper ventilation and makeup air. When a house is depressurized, air is pulled into the home through the heating chimney and the unhealthy air can enter through the garage, attic or crawl space. Soil gas can enter through cracks in the foundation or around the sump area. Air can also be pulled down interior and exterior walls and exits around electrical outlets bringing with it what was in the wall cavity. The best solution is to use a well-designed ventilation system that can deliver fresh air all year long, even when not heating or cooling. This type of an approach allows a strategy for managing moisture and indoor pollutants while still delivering comfort and efficiency to the occupants. The American National Standards Institute (ANSI) and the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) have developed minimum standards for ventilation: ANSI /ASHRAE 62.1 Ventilation and Acceptable Indoor Air Quality.
NORA Advanced Air Flow
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