Air duct replacement can undo many errors of the past. In the days of cheap fuel, builders didn't give much thought to energy efficiency. Duct systems were frequently sized incorrectly — sometimes undersized but often oversized. In addition, the ducts themselves weren't constructed and sealed to last as long as the home. Over time, they deteriorated and developed leaks.
Studies have shown many duct systems are leaking as much as 40% of the air they are supposed to convey to the home. In many cases, the remedy is air duct replacement.
When you're retrofitting your home with new ductwork, keep these five considerations in mind to ensure efficiency for 21st century energy costs.
- Before duct replacement, your contractor should accurately size the ducts, using results from the Air Conditioning Contractors of America’s Manual D. For accurate data, the Manual D calculation must be based on an up to date* heating/cooling load estimate generated by the ACCA’s Manual J. (*Often, the nature of the home's heating and cooling load changes with improvements to the home such as home sealing, new windows or upgraded insulation. This changes everything and affects the size of the equipment and connected ductwork. So it is always best not to trust the size of the existing unit and to re-evaluate the load estimate before work is contemplated.)
- As much of the ductwork as possible should be located in conditioned areas of your home. Ducts routed through unconditioned areas such an attic or crawl space should be insulated and thoroughly sealed. Even if you don't replace the duct system this is always good advice for duct work located in these areas.
- Wall voids and channels between joists were sometimes used as substitute return ducts in original construction. They are leaky and draw unconditioned and contaminated air into the system. They should be replaced with standard hard ductwork made of metal or fiberglass. At a minimum, they should be thoroughly sealed if left in place.
- Original duct sections were sometimes simply pressed together and sealed with tape. Many have come apart over the years. When your technician retrofits your ducts, all joints should be mechanically secured with screws and sealed with mastic sealant. The system should be pressure-tested after installation to verify that leakage is within the minimum specs for airflow. Note: Oddly, "duct tape" is good for many applications, but almost never to seal ducts!
- Dampers on each duct run facilitate more precise balancing of airflow to individual branches. After the system is balanced, the dampers should be secured in a fixed position for correct airflow.
At P.K. Wadsworth Heating & Cooling, we’ve dealt with heating and air conditioning needs in greater Cleveland since 1937. Contact us for information on improving your home's comfort and efficiency with duct replacement.
Paul Wadsworth is the President and Owner of P.K. Wadsworth Heating and Cooling. For 37 years, Paul has been providing heating and cooling services to the Greater Cleveland area. P.K. Wadsworth has been a trusted Cleveland HVAC service company for 75 years. The company understand the area's construction and local heating and air conditioning needs. Paul has an MBA from the University of Michigan and a B.S., Industrial Engineering from Purdue University. He's been President of the Cleveland Air Conditioning Contractors of America and a founding member of the local chapter. Paul was born and raised in Cleveland and has been active in the local community. He resides in Cleveland, Ohio with his wife and two sons.
The opinions and statements contained in this article are for general informational purposes only and are not instructions. Only trained, licensed and experienced personnel should attempt installation/repair. The author assumes no liability for the opinions/statements made in this article. Any individual attempting a repair or installation based on this article does so at their own risk of loss.