There’s more to energy savings than just having an efficient heating and air conditioning system. Good ductwork design plays a fundamental role in a home’s overall energy efficiency. By having a properly designed duct system from the onset, your HVAC system can effectively provide a comfortable indoor environment without wasting energy or creating unnecessary stress on the system itself.
Proper ductwork design is judged based on the following criteria. Any ductwork worth its weight should abide by these five design factors:
In decades past, some contractors took to time- and “money-saving shortcuts to quickly finish duct systems. It wasn’t out of the ordinary to see wooden wall voids or enclosed ceiling joists used to push air through the home. Unfortunately, these shortcuts often came at the expense of energy efficiency and HVAC system longevity.
Quality ductwork design depends on using the proper materials for building ducts. Metal, fiberglass and other permanent materials should be the only ones used for ductwork throughout the home. Most importantly, all ductwork should be designed in accordance with the Manual J, D and S guidelines set by the Air Conditioning Contractors of America (ACCA).
Ducts Routed Conditioned Zones
When it comes to energy losses, routing ducts through unconditioned zones can be a killer. When uninsulated ducts are exposed to unconditioned spaces like attics and crawl spaces, the temperature extremes can easily rob your HVAC system of its efficiency and capacity to provide adequate comfort.
Ideally, it’s up to your contractor to route ductwork so that it avoids unconditioned spaces. When that’s not possible, the next best step is to wrap ducts in insulation rated at R-8 for unconditioned attics and R-6 for other uninsulated areas.
Supply and Return Vent Paths
An ideal ventilation setup involves placing dedicated return ducts in each room featuring a supply duct, but that’s not always possible to do. For this reason, most homes have a return duct situated in a central, common area such as a living room or hallway.
When it comes to airflow, the path of least resistance is usually the best path to your home’s return duct. Obstructions such as furniture can slow down or even block air from getting where it needs to go. To increase energy efficiency and ensure reliable HVAC operation, you should remove or rearrange potential obstacles so they won’t block airflow to the return ducts.
For obstacles that can’t be moved out of the way, such as doors and walls, you may have to incorporate pass-through grilles within doors or install ceiling-mounted jumper ducts that allow air to pass from one room to the next.
The conditioned air that enters your living spaces through the supply ducts does so under positive pressure, whereas the return air is drawn out of those spaces through negative pressure. Both must be balanced in order to maintain neutral air pressure throughout your home. Your HVAC system operates best when balance is achieved.
Manual dampers can help keep your home’s pressure balance in check through occasional adjustments as needed. These dampers should also have mechanical holds to prevent the damper from moving out of position over time.
Ductwork Sealing and Testing
Leaks and gaps in ductwork are responsible for most energy efficiency losses throughout the typical home. Not only does conditioned air escape, but dust and debris can also get sucked into the ducts through these small tears and crevices.
It’s important to check and double-check all of the duct segments as they’re being put together. Not only should duct segments be securely connected via sheet metal screws, but the joints should also be sealed with metal foil tape, mastic sealant or a combination of the two. In addition, your contractor should also leak test the newly joined ductwork to ensure there aren’t any major air losses.
Learn more about ductwork design solutions from the pros at Ray & Son Heating & Air Conditioning, or give us a call at (229) 686-5531.