Derek Cole explains why heating systems smell like dirty socks when they first turn on: bacteria growing on the evaporator coil or drain pan. He also covers carbon monoxide detectors, which must sit at floor level because CO is heavier than air. Ceiling-mounted smoke/CO combo units won't catch it.
Questions this video answers
The sour, mildewy "dirty sock" smell comes from bacteria growing on the HVAC coil or in the drain pan; using UV light on the coil and a chemical drain‑pan treatment eliminates the bacteria and the odor.
Because any gas‑fired appliance can produce carbon monoxide, especially if a heat exchanger cracks. CO detectors must be placed at floor level in each living and sleeping area (and on each floor) because CO is heavier than air; ceiling‑mounted units are ineffective for CO detection.
Chapters
Hey, on this episode we talk about a sour smell when my heating comes on and why did your technician offer a CO alarm at my house? You ask your comfort and energy questions and they get answered. This is the Ask Derrick Cole Show.
What is that sour smell when I turned my heat on?
The smell you're getting when you first turn your heat on is because of— well, it's really bacteria. It's something that could be in the drain pan or or it could be on that coil causing that smell to happen. So when you first activate your heat, you get that kind of a— we call it a dirty sock. It's a kind of a sour smell, a mildewy kind of smell, and that's really from that bacteria being on that coil or in that drain pan, and you're getting that smell because it's coming up into the environment and blowing it into your house. So how you solve that problem is UV. UV is the only way to solve that problem. You put a pan treatment treatment into the drain pan to kill any algae or bacteria because if it just sits there, it's going to die and it's going to smell. So you want it to be taken care of by drain pan treatment and by UV on that coil so nothing can grow on that coil, therefore nothing can grow in the pan. That make sense? Man, that's a quick answer. I've been going like 7 minutes last couple of shows.
Why did your tech tell me I needed a carbon monoxide detector?
Because you don't have one. That's why I told you you needed one. So if you have a gas appliance in the home at all—stove, furnace, anything in the home running off of gas—you should have a carbon monoxide detector in the home. A lot of clients we go to have combination smoke and carbon monoxide detector in the house. But the problem is with the CO part of it, or the carbon monoxide part, is that when it's up high on the ceiling, it's not doing you any good whatsoever because carbon monoxide is heavy. So the best thing to do is put it on floor level with the outlets on the floor, on the wall. That is where it needs to go. If it's up, up there high in the ceiling on top of the wall, It's good for a smoke alarm, but it's not good for a CO alarm. So if you don't have one, you need one. It's recommended you have one in all living spaces. If you have multiple levels to the house, you have one on each level. Even if you have a single-story house but multi— or you have a bedroom on one side, bedrooms on the other side— then you should have one on that side and this side, basically so it can go off if you have Any kind of carbon monoxide, which is odorless, you can't smell it, you can't feel it, you can't sense it, so the alarm sets it off. And most cases people get in trouble because it's usually at nighttime when they're asleep when it starts to bother them. It's something you can't feel going on, so you need that alarm in the living space or in the sleeping space to alarm you when that hazard is there, and as soon as you have a CO alarm go off, you need to have it checked out. And if you have— the biggest thing with a gas furnace is when you have a cracked heat exchanger. When you have a cracked heat exchanger, that CO, it's possible that CO can now come into the home, come into the living space, and that is very, very dangerous. So whenever we see a cracked heat exchanger, we turn it off for that reason. It's a safety hazard. Not saying it's a 100% chance they're going to come in, but You don't even want the possibility of it coming in, so we're gonna shut it off and kill it so it doesn't affect you and your family. And the reason he went to your home and said, "Hey, you need one of these alarms," is because you either don't have one or you have one in the wrong spot. Again, if you have a carbon dioxide and smoke detector alarm in the ceiling, no good for you. You need it at ground level where it can detect it before it gets— if it gets to that point and goes off, Then the house is empty anyway because everyone in it is dead because it's gotten that, that bad. It's kind of morbid.
