You turn on your system and you smell... dirty gym socks. "Dirty sock syndrome" sounds like slang, but it's the real term HVAC pros use for this problem.
What causes it?
Bacteria build up on your system's indoor coil. You won't know it's there until the smell starts, usually when:
- Your heat pump goes into defrost for the first time in the fall, often the first time it drops below 40°F.
- The system switches between heating and cooling in the same day, which is common in a Southern Maryland spring.
The coil temperature drops, humidity rises, and the bacteria give off the smell. Running only heat or only cooling for a while can make it go away, but that only hides the problem. Gas furnaces rarely get it because they run hotter. It's more likely in humid homes and homes with pets.
Does it mean my system is broken?
No. It isn't a mechanical or electrical problem.
Can it affect my health?
Usually not, but it can bother people with asthma or a weakened immune system. Left alone for a long time, it can spread through the ducts and become harder and more expensive to fix.
Can I fix it myself?
We don't recommend it. Instead, have the coil properly cleaned, and consider an air purifier such as an iWave-R, which helps keep it from coming back rather than treating it every year.
How do I keep it from coming back?
- A whole-home air purifier to control microbes and spores
- A better filter, especially if someone in the house has allergies or asthma
- Changing your filter as often as the manufacturer recommends
- Regular inspections and coil cleaning
- A dehumidifier if your home runs humid
Smell it in your home? Book a visit and we'll confirm the cause, fix it, and help keep it from coming back.