You Have WHAT Living in Your HVAC System? Dealing with Bats, Bugs, Birds, and More

Posted on: 3 October 2016

Picture this scenario. Spring has arrived, and you've settled down for a long nap in front of the air conditioner. You turn it on, and suddenly you hear a horrendous skittering inside the vents. Is your HVAC system about to die? Have aliens moved in? Either diagnoses are technically possible—or at least they cannot be scientifically ruled out in advance—but the more likely cause is that you have something much less exciting living in your HVAC system. Though the nooks and crannies of a heating and air-conditioning system might seem inhospitable, plenty of animals enjoy calling these systems home, especially if they become loose, broken, or improperly secured. In this article, you'll learn about some of the most common animals found within HVAC systems and how you can prevent them from getting in in the first place.

Rats, Squirrels, and Rodents

Easily one of the most common groups of animals to find nesting in your HVAC system, rats, squirrels, and rodents find the perfect home in air ducts. While they often come in through a broken section of ductwork or a loose entry vent, certain rodents are strong enough to chew through metal and may actually make their own hole instead.

Both rattus rattus and rattus norvegicus can exert up to 24,000 pounds of pressure per square inch and have been known to chew through concrete and steel.

That bodes a pretty sad picture for your air ducts, which are frequently made from aluminum or sheet metal and not all that difficult to chew through.

Signs of rats, squirrels, and rodents living in your air ducts include skittering sounds at night, particularly when you turn the vents on, finding droppings throughout the house, or finding small holes chewed in the siding or wall of your house close to the entry point.

Should rodents die within the ductwork, you'll find you have an extremely obvious sign on your hands—your entire home will likely stink. A sour, musty smell that's unidentifiable is very common with dead animals in ductwork.

If you suspect a rodent is living in the ductwork, it's extremely important to contact both an HVAC specialist and a pest-control specialist for help. Often, the duct work must be disassembled and cleaned thoroughly, as droppings can spread allergens and cause respiratory issues, but it is vital that the home be treated for pests so as to get rid of the problem in the first place. Otherwise, the problem may simply recur.

And what better place to breathe them in than when particles fly through your air?

Bugs, Birds, Bats, and Butterflies

You aren't as likely to notice any of these animals interfering with your HVAC system, but that doesn't mean that they aren't a problem. In fact, air-conditioner intake grates can become clogged with dead insects quite easily during the summer, especially if you live in a particularly swampy or wet area where bugs are common. Much as they will eventually clog the grate of a system, they will eventually clog your air conditioner, too, and that can lead to a dead motor if the clog is bad enough.

It's fairly easy to identify insects like bugs and butterflies in your system; check the grate and look for brutalized body parts. Listen carefully for buzzing inside. If you do see carnage on the outer grate, you can use a soft paintbrush to gently remove them, but you should never open your system yourself unless you know what you're doing.

Opening a full-size permanent air-conditioning unit exposes you to extreme electrical risk. Only undertake this task if you are professional.

If you hear buzzing inside, it's especially important to stop and call an HVAC specialist. It isn't unheard of to have bees or wasps build nests inside window units, and there is a sting risk upon removal. 

Sometimes, the issue is not that your system is clogged but that birds have decided to nest under the eave of your vent. If the nest isn't impeding the system, and you find it in the spring, you may decide to simply monitor the nest until the babies move on. Once the babies have fledged, it's safe to remove the nest for most species.

The same is true for bats. However, there is one caveat: certain bats and birds may be specially protected by law.

Removing animals from your HVAC system is far more difficult than preventing them from getting in to begin with. Bi-yearly checkups will identify issues like holes, weak sections, and broken ducts quickly before a problem occurs. However, despite even the best issues, sometimes animals do get in. If you suspect animal infiltration, or if you have any other question related to your HVAC system, contact a professional for a one-on-one consultation.