A new furnace can be a costly investment, sometimes upwards of $5,000. Furnaces have come a long way since the old days when 70 percent efficient units were considered “high efficiency.” Now, high tech condensing furnaces can be up to 97 percent efficient, which means for every dollar you spend on heating, you get 97 cents back in heat. An efficiency loss of only three percent is pretty remarkable, but what about your duct system?
Through extensive research, the U.S. Department of Energy has determined that the average duct system in a house leaks anywhere from 20-40 percent. That means that for every dollar you spend on heating, you lose 20-40 cents to the great outdoors. This also means that the overall efficiency of your whole heating system will also drop. That very expensive, high tech 97 percent efficient furnace can be leaking 20-40 percent of the warm air it’s producing. The good news is these leaks can be sealed up, making for a more comfortable and affordable home.
When duct systems are installed in homes, the best practice is to make sure every joint where two ducts join are sealed with a product that will last as long as the rest of the system. Systems in older homes were rarely sealed at all, and some more recently built homes only were sealed with duct tape. Duct tape is great for everything but sealing ducts. Over time it disintegrates and falls apart, becoming ineffective. Newer products such as butyl tape and duct mastic work much better at sealing leaks and will last a very long time. It is also not uncommon for ductwork to become disconnected over time. Sometimes this is caused by the ductwork being jostled while a worker is in the attic or crawlspace, and sometimes animals will claw and chew their way into the ductwork. All of these factors can contribute to leaky duct systems.
A leaky duct system can also cause comfort and health problems. Poor airflow to a room could be a disconnected duct, causing it to be cold in winter. A leaky return side of the duct system can pull dusty attic or crawlspace air into the house, creating poor indoor air quality. A disconnected supply duct can cause the house to be negatively pressured since the return side is still pulling the same amount of air into the furnace. This negative pressure can sometimes cause a water heater to backdraft, pulling carbon monoxide into the home.
The best way to determine if your duct system is leaking is to have a duct leakage test performed. As part of APS’s Home Energy Checkup program, APS customers can have a comprehensive home energy audit performed on their house for $99, which includes a duct leakage test. This test is performed by a certified Building Performance Institute, APS participating contractor. Once the test is completed, the same contractor can then seal up the duct system and re-test to make sure the leaks are sealed. APS provides up to $400 for duct sealing and the City of Flagstaff provides another $100. This usually covers over half of the total duct sealing cost.
The resulting energy savings from duct sealing can have a payback of anywhere from six months to two years, usually making duct sealing the most cost effective energy efficiency improvement a homeowner can make. Duct sealing will almost always have a much faster return on investment than upgrading windows, water heaters and furnaces. The added advantages of increasing comfort and improving indoor air quality make duct sealing a very worthwhile home improvement. FBN
Written by Eli Chamberlain. Learn more about Cozy Home AZ, online.