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Can Animals get into My HVAC System

The 3:00 am call from Kingsport

My phone rings. I check the time it is around 3:00 am. A woman in Kingsport is calling to tell me that she just opened the grate on the return side of her central air system because she heard noises. When she looked in and saw an opossum looking back at her. When she called me she was panicked. I grabbed my work clothes and jumped into the truck. When I arrived she told me that this was the second time in the last few months this had happend. She had already spent about $700 having ductwork repaired. I felt really sorry for this lady. I ended up finding an opossum in in her crawlspace and stuffed it into a trap for removal. She ended up spending even more money repairing the ductwork again and resealing the entrance (the HVAC guys had tried to seal it the first time).

Wildlife passing through Holes created for AC lines - A Regional Problem?

I serve all the tri-cities area and beyond including Bristol, Kingsport, Johnson City, Jonesborough, Elizabethton, Abingdon, Church Hill, and Fall Branch. I see this problem repeat itself everywhere I go. HVAC guys in our area just don’t seem to understand that it only takes a small hole in a foundation to let animals in. I can show you two customers in Elizabethton just houses from each other who had the same problem. I have had the same thing in Johnson City. I have not worked outside this area, so I can’t compare, but I can sure tell you that it is a problem around here. Bottom line, it is a good idea to have your home checked out. I can’t tell you how often I hear people say “this never happened before”

CAN ANIMALS GET INTO MY HVAC SYSTEM?

In short, absolutely yes! Any midsize animal that can climb under your home or in your attic can damage the ductwork or your HVAC unit. Once the system is opened, that animal or another individual may enter the ducts and roam freely. At that point, it may even enter living spaces by pushing floor registers up. I once got a 11:00pm call to pull a raccoon out from under a sofa. When I showed up just the tail of the raccoon was sticking out from under the couch. It had pushed the grate up, and the grate had fallen back in place after it came into the living room. Three teenage girls found it when they came home. By the time I got there, it was a real circus. Everybody was there including grandpa, grandma, cousins, and some uncles. I had the animal caught inside of about 15 minutes. I think some were disappointed that there wasn’t more excitement.

Main lines in a heating/cooling system can be made of flexible ductwork or they can be made from sheet metal. Sheet metal ductwork is not usually as problematic as flexible ductwork. It is solid sheet metal covered with some type of insulating material. Steel sheet metal is too hard to penetrate with teeth and claws. Attacks on this part of the system are not successful unless the animal walks on top of the ductwork and it separates at the joint, however the insulation on the outside is vulnerable. Insulation on the exterior can be torn off deliberately or be ripped off when the animal climbs up the side of the duct or walks on top. Once this happens, the system loses efficiency and heating/ cooling bills will start to climb.

Usually the “softest” part of a system is the flexible ductwork. Flexible ductwork is a combination of wire, plastic, and fiberglass insulation. Rats will tear/gnaw their way through the walls of this ductwork while raccoons will pull and rip with teeth and paws more like a dog. If you think that your problem is related to either of these species, please have a look at our pages on How to Remove Rats and How to Remove Raccoons from your home. The result is the same either way. Once the ductwork is compromised, the entire system is open to invasion and most of the cool or warm air blows out into the crawlspace or attic.

I mentioned rats and raccoons in the paragraph above, but other species show up in HVAC systems too. Opossums could appear in ductwork, but aren’t very likely to do “deliberate” damage by clawing their way through the walls of the duct. They are “secondhand” burrow users and tend to crawl into whatever cavity that they find. However, if a piece of ductwork is open, they are more than happy to crawl inside. They seem to have a special affinity for insulation and are good climbers. Their excellent climbing skills can take them up pilings and pipes into floor supports where they can access insulation and ductwork. If you think that you are having opossums, check out our pages on opossums: Removing Opossums from Your Home and Everything about Opossums the Smart Homeowner Should Know.

I believe that open ductwork appears much like a hollow log or underground burrow. This stimulates natural denning instincts of animals and traffic inside the ductwork system can develop. We do not find mothers with litters inside operational ductwork. I believe that the strong wind currents inside the ductwork makes it inhospitable for newborn kits, but I have seen plenty of muddy tracks inside the ductwork along with droppings. Particles from all this mess is inside your system and it is being blown right into your home.

So many times, homeowners find out that they have had a long standing problem they were not aware existed. I have dumped small buckets of raccoon droppings out of torn ductwork. Each dropping was the size of a medium sized dog dropping. The best way to keep this from happening is to keep critters out of your home in the first place. This is going to mean securing foundation and rooftop entry points.

Scheduling an annual inspection is a good idea too. If you would think that you might need to schedule an inspection please contact us.

Serving the Tri-cities region including: Bristol Va., Bristol Tn., Kingsport, Johnson City, Elizabethton, Jonesborough, Abingdon, Elizabethton, Erwin, Greeneville, and beyond.