Problem: Noise from a forced-air furnace.
Cause: The fan or combustion systems for some modern high-efficiency furnaces are noisy.
Solutions: Modify the supply and return air ducts.
- Use a vibration break between the furnace and major ducts to stop vibrations from getting into the duct walls as shown in Figures 25a and 25b.
Figure 25a - Flexible Duct Connector.
Figure 25b - Flexible Rectangular Duct Connector
- Fasten acoustic duct liner material, normally glass fiber with a special facing, on the inner surfaces of ducts to reduce transmission of noise along the ducts. Lining the large ducts closest to the furnace is usually enough. Make the duct cross section, with the lining installed, large enough for proper airflow.
- Locate the furnace as far as possible from rooms where quiet is important.