Why do air ducts smell?
Most homeowners do not bother much about the air ducts that run through their house to cool and heat rooms as on when required. Being hidden from their sight, running through walls, crawl spaces, attics, and basements they only turn to take a look at them when they cause troubles. One such instance is smelly ducts. Bad odor issuing out of the ducts can make your time indoors unbearable. There could be many reasons for duct odor. Let’s take a look:
Smell from Pets: This could be on account of pets kept in the house by previous owners who lived before you moved or pets currently living in the house with you. In case you do not have pets, you can trace the presence of animals in the past through the stench of pet urine or fecal waste, animal hair, cat boxes, dog dander, cat dander coming out of the ducts. Besides pets animal smell in ducts can also occur when a moose, rodent or bird die in the duct of the house. These animals sometime use ducts as in routes to the house. They infest them with their urine and dropping, which make ducts smelly. Sometimes they get trapped and die. The animal smells are often described as a vague noxious stink. When cleaning you ducts of animal wastes or carcasses, remember that their urine trails and smell of droppings have to be eliminated. Otherwise the rodents or vermin would soon trace them to find their way back into your house and dirty the ducts on the way.
Carbon monoxide (CO): It is very difficult to detect the presence of dangerous carbon monoxide just by smelling it out. It is an odorless gas that will sneak into your room with other gases. Carbon monoxide leakage happens when the exhaust gases from your wood stove or furnace is not being vented out safely. CO along with other combustion gases gets into your ducts. This is also called back drafting. You can detect a bizarre smell of other combustible products in this case. Leakage of combustion gases happen usually due to crack in the heat exchanged or due to defect in return air duct system that draws flue gases into the duct system through that route. Always keep a CO detector at home to detect the leakage of carbon monoxide. These are easily available today in the market.
Chinese dry walls: There have been many reports of unbearable odor and health hazards caused by Chinese dry walls in the United States. These walls are being imported to the US since 2001. The boards made of gypsum paste and pressed between two sheets of paper are widely used to make interior walls and ceilings. Read on to know an incident that took place recently in Florida:
Richard and Patricia Kampala bought a house in Cape Coral, Florida. As they moved into their new house, they experienced a gut-turning smell which could be likened to putrid eggs. At first they did not give it much thought assuming it for the smell of the new house. In fact Patricia bought some scented candles to lighten the smell. The ordeal started when the metal coil in the central air conditioner completely altered its color to black and got corroded so badly that it had to be replaced within a few months. The mirrors in the bathrooms turned black. The motherboard had to be replaced three times and their son's Xbox stopped working. Things worsened as they suffered nose bleeding, headaches, and respiratory attack.Thereafter it was the air conditioner company who helped them to trace the reason for all this. They said it could be due to Chinese dry walls fitted in the house. The Kampfs were astonished.
Chinese dry walls fitted in your house can give out choking stench that will travel through your ducts. If you detect it do the needful before long. These dry walls use sulphur and other elements that give out gases which are corrosive. They can damage HVAC equipment as well as other building components.
Drain odors: Sometimes the drainage system of your house or somewhere near the house may not be functioning properly. You can hear a "bulb bulb" or "glug glug" noise. There could be a partial drain blockage, venting problem, or a failing septic system. These will lead to bad smell coming out of the drain. The smell gets distribute din your house through the ducts. Call a plumber ASAP to set the drain in order.
Electrical smells: These smells sound like something is overheating or burning. This reason for this could be a burning electric motor, or bad and torn wiring. The smell can also be from burning materials like winding, insulation, lubricants. If you detect such an odor calla technician to know the cause. Burns can cause damage to your system and lead to accidents like HVAC fire. Some people think that burning smell from ducts is justifiable because the furnace is doing its job.After all, its job is to burn the fuel to produce the heat. Although, truly so, in all well-functioning furnace the smell should not reach your nose. Sometimes burning smells come due to oil leaks in the furnace. This can be dangerous if not checked on time.
Oil tank leaks: The houses that use oil as a fuel to run their furnaces usually have oil tanks in the basement. Sometimes the tanks could be leaking which can lead to smell of oil. The odor is further sent to all rooms through air distribution system. If you feel such odor, go and check the tank in your basement. If the tanks is alright the smell can also issue out of our furnace, filter, or pipes, and it is a good idea to schedule an appointment to have your heating system inspected and repaired if needed. Sometimes oil tanks also spill when they get overfilled with oil. The oil could overflow or the tank could overturn. Oily smell can come if fuel's accidentally poured into septic tank. Always seek professional help in such cases. If you duct registers are located close to source of oil leak or spillage then you will get a strong odor of oil in your rooms.
Musty odor: Active growth of molds and mildew is quite common in uncleaned and unmaintained ducts. If moisture along with dust and debris is trickling in your ducts, then molds will start growing on matted dust layer. In that case you will find a musty odor coming out of your ducts. You will need to call a duct cleaning company that will treat your ducts with biocides to stop mold growth. However biocides are only applied after your ducts have been cleaned of dust and debris thoroughly.
Other reasons: Beside these there can be other sources of odor in the duct work. If your ducts have been painted, the smell of paint will be circulated through the air conduits. If plastics or vinyl have been used in the building recently, then the odor reaches the rooms through the duct way.
Radon: This is a very dangerous radioactive gas that seeps out of the ground and build up in houses and workplaces. The concentration is higher near the basements, ground floor buildings. Radon can get into your ducts if there are leaks. It will get in with other fumes. It is odorless and therefore difficult to detect. You should get your duct system checked from time to time to detect the presence of radon. Radon can be the cause of lungs cancer.