Persistent home odors are always a sign that something needs to be investigated. One of the most infamous is the “dirty sock” smell that can sometimes spread throughout a home. In these cases, the unpleasant odor is usually associated with laundry or sweat. Many homeowners start suspecting that there’s something wrong with their washer or dryer. While that’s a good guess, the real culprit of Dirty Dock Syndrome is usually something else that needs immediate attention. Here’s what’s going on.
What’s Causing It
Inside HVAC systems, there is a component called the evaporator coil. This is a metal coil that is exposed to air with easy access to the refrigerant flowing inside. Here, the refrigerant absorbs the heat in the air and carries it away. This cools down the air, making it suitable for air conditioning purposes – or allows units like heat pumps to pass heat along to indoor air and warm it up during colder temperatures.
Because the evaporator coil is exposed to open air, it can start to get dusty. In areas with lots of moisture, that dust can build up with other grime and debris, too. Ordinarily, this stuff doesn’t smell very much on its own, but it can attract bacteria that will grow on the coils as it finds organic matter to eat. These bacteria – just like the kind that builds around human sweat – secretes waste with a very unpleasant odor. That smell gets picked up by the HVAC system and spread around the house, which is why it seems to come from everywhere.
When It Happens
Very active evaporator coils don’t usually build up a lot of bacteria (they tend to stay too hot for this). However, during downtimes when the coils aren’t used very often, lots of debris can build up and start creating problems when it is turned on – especially when accompanied by moisture. We see this a lot during spring, where moisture and intermittent running of the HVAC system combine for ideal conditions.
It’s also a more likely problem with heat pumps, which use evaporators to move warmth in and out of the house as needed, and don’t reach the bacteria-killing temperatures of furnaces. With a heat pump, this problem can occur at any time but may be more common in the fall.
What to Do
A dirty evaporator coil isn’t just about the smells. It can also create problems with proper heat transfer, which means air isn’t cooled or warmed as quickly as it should be, and your whole system has to work harder and longer to achieve the same effects. That’s why it’s always a good idea to make sure your evaporator coil stays clean and to wipe it free of dust as the seasons change. Sometimes, for especially problematic situations, you can apply a coating designed to prevent bacteria growth in the future. It's also a good idea to check your air filter and any other spots where bacteria may have built up.
If you aren’t sure where the evaporator on your unit is or prefer that cleaning be done with scheduled maintenance, contact Guaranteed Heating & Cooling today, and we’ll be happy to set something up!