Do I need to replace my HVAC duct, have air duct service, or repair my ductwork installation?
Inadequate airflow causes a loss in total capacity, a loss in sensible capacity, a loss in efficiency, and a reduction in reliability (due to refrigerant floodback to the compressor and distorted refrigerant system feedback to the servicer).
In 1996 a study commissioned by Arizona Public Service Co., the utility investigated total airflow in newly constructed houses in Phoenix. The study revealed that:
- The airflow in 14% of the tested homes was at 90% of nominal airflow (360 cfm/ton).
- 39% of the homes tested at 80% of nominal airflow (320 cfm/ton).
- 14% tested at 70% airflow (280 cfm/ton).
- 7% tested at 60% of nominal airflow (240 cfm/ton).
Of course, this sample does not necessarily represent the entire country, but I suspect that Phoenix is not the only place that suffers from this phenomenon. A test by Texas A&M University (Table 1) shows the ramifications of low airflow on capacity and efficiency. Notice that a 25% reduction in airflow (300 cfm/ton) causes a 7.5% reduction in cooling capacity and a 4.2% reduction in efficiency.
This gives you some idea of what it costs the consumer to have a system with low airflow. Of course, the consumer also pays a high price in reduced reliability; 60% of the homes tested in Phoenix had a total airflow of less than 350 cfm per ton. Why does this matter? Because besides poor performance issues, 350 cfm/ton is the minimum airflow recommended by most manufacturers for ductwork airflow and anything less will require air duct repair.
Louis Bruno below tells you ALL about air duct repair, ducted air conditioning, and potential duct replacement!