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Air-Flow FAQs

Q: What causes poor air-flow? How can I correct this problem?
A: Proper air flow is accomplished by: 1) A fan that is capable of producing the proper pressure and quantity of air needed for the structure. 2) A distribution system (ducting) that will allow it to do its purpose. The only way to find and correct a problem is through a on-site home evaluation. The problem could be the equipment, the ducting, or a combination of the two.


Q: I live in a double-wide manufactured home. I have noticed half of the home is not comfortable, but the furnace seems to be working fine. What could be causing this?
A: During original installation, the heating ducts for the 2 halves of the home are generally connected in the crawl space with a 'jumper' duct. This ducting is usually made of a flexible, vinyl-covered ducting material. It is possible that one end of the ducting may have come loose and/or possible animal or rodent damage. It is common to have rodents chew a hole through this type of ducting material. Evaluating this problem is important, as serious health risks can occur. Replacement of this type of ducting with insulated metal ducting is recommended.

Q: How does ducting construction and installation affect air flow or efficiency?
A: The materials the air moves through, how the turns are created, and any restrictions to the air flow must be compensated for in order for the air to get from the furnace to each room properly. If the air cannot move properly, then the efficiency of the system is poor (i.e., if we subtract the heat coming out of the registers into the home from the heat the furnace is producing, we know the total system efficiency. The furnace may be a 90% efficiency gas furnace, but due to restricted air flow the total system efficiency could be 63%, as was the case of a 4 year old home in Boise.).

Q: I have notice a loud whistling noise coming from my return air grill from the time I moved into this house. How do I fix this problem?
A: Noise at the register or return grille is caused by high velocity. Possible solutions include: a high volume return air grille (more spaces between the louvers), increasing the return air grille size,  increasing the return air ducting, or adding additional return air ducting to a secondary return air grille.