How to Stop Wasps Coming Through Vents

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Wasps are some of the most common pests in homes. Unfortunately, they do more than just irritate you, they also sting and some people are dangerously allergic to them. Vents are one of the most common ways that wasps get into the house. Fortunately it is very easy to stop wasps and other insects from entering the vent.

Installing a backdraft damper will stop wasps and other insects from entering the duct and your home. The damper can be installed either inside the duct or at the termination point on the roof/wall.

Next let’s find out what a backdraft damper is and which one to choose to make sure nothing gets past it.

I will also let you know why the most common solution for keeping pests out of the ducts is not optimal.

What is a Backdraft Damper?

AC Infinity 4" Backdraft Damper, One-Way Airflow Ducting Insert with Spring-Loaded Folding Blades for 4” Ducting in Range Hoods and Bathrooms Fans

A backdraft damper is a part of the ventilation system. Typically they are installed inside the duct itself. Like the one pictured above. The flaps are spring-loaded and are closed when there is no airflow. As soon as an exhaust fan is turned on the air pressure will push on the flaps and they will open letting air out.

Here is an helpful guide if you would like to learn more about ventilation dampers.

HVAC OV 6" inch Duct Connector with air Backdraft Damper. Made of Durable Plastic. Ducting with Non Return Valve.

Most backdraft dampers are not very airtight and allow wasps and other insects to enter the duct. This is why it is very important to choose a model that has rubber seals and is spring loaded.

This will ensure that there will be no cold drafts or wasps coming in through your vents.

 Install a Quality Backdraft Damper to Prevent Anything Entering the Vent or Your Home

The most effective way of keeping pests out is by installing a backdraft damper. It can be installed either inside the duct or at the termination point at the roof/wall in the form of a vent cap.

Both options will work and you can choose whichever is easier to install.

In addition to keeping pests out of the ducts here are a couple of more reasons to install a backdraft damper

  • No more cold drafts from the vents
  • Energy savings
  • Better air quality
  • Condensation won’t drip from the vent

Backdraft Damper Inside The Duct

A quality spring-operated rubber-sealed damper will completely seal the duct when the exhaust fan is not in use. This makes it impossible for anything to enter the duct. The best location for the damper is close to the external termination point.

If you install the damper too far inside the vent, you will leave room for the wasps to nest within the vent. The optimal distance from the wall/roof vent cap is about 10 inches.

Wall/Roof Cap With Integrated Backdraft Damper

Builder's Best 084633 Galvanized Steel Roof Vent Cap with Removable Screen & Damper, 6" Diameter Collar, Black

If you don’t have access to the attic to install the damper inside the duct you could replace the wall/roof cap with one that has an integrated damper. In the picture above the vent cap has a metal flap that closes with gravity when the exhaust fan is not running. This will effectively keep anything from entering the duct.

Tip: Most of them are noisy when windy, if you live in a windy area take a look here to find out how to modify them to make them quiet. The AC infinity internal damper is preferred to this.

Avoid Vent Wall Caps With a Net

Nets integrated into vent caps will keep insects out, but they will drastically reduce the airflow and energy efficiency of the ventilation system.

For this reason vent caps with nets should be avoided and a backdraft damper installed instead.

Vent Systems 4'' Inch - Graphite - Soffit Vent Cover - Round Air Vent Louver - Grill Cover - Built-in Insect Screen - HVAC Vents for Bathroom, Home Office, Kitchen

Your Existing Backdraft Damper Is Probably Not Airtight

A backdraft damper should only allow air in the vents to go one way; this way they allow only air from inside the house to go out of the house and not the other way. If your damper allows air, debris, pests, or insects to get into the house, then there is something wrong with it. Most cheap dampers are not sufficiently airtight to prevent insects from entering the house via ductwork.

Gravity-operated dampers such as the one pictured below are terrible. If the installation angle is not perfect, they will not close all the way. Allowing air, dust, and pests through. Another downside is; they are notoriously noisy when it’s windy outside. The flap is picked up and dropped down by the wind. It will produce an annoying banging noise.

HVAC OV 6" inch Duct Connector with air Backdraft Damper. Made of Durable Plastic. Ducting with Non Return Valve.

Which Backdraft Damper is Best?

Everywhere on this site, I recommend AC infinity dampers(amazon link). Not only do their products look great. They are also designed using quality components with the strictest quality control procedures in the industry. (For residential dampers)

AC Infinity 4" Backdraft Damper, One-Way Airflow Ducting Insert with Spring-Loaded Folding Blades for 4” Ducting in Range Hoods and Bathrooms Fans
AC Infinity backdraft damper

The flaps on the backdraft damper must fit perfectly inside the housing. This is where the AC infinity dampers shine. The flaps move easily, yet close completely when the exhaust fan is turned off.

There can be no binding or excessive resistance, otherwise, the exhaust fan will not be able to open the flaps all the way and the ventilation system will be inefficient.

Besides keeping wasps and other pests out, an airtight damper will keep cold or hot air out of the house. Your house will be much more comfortable with just the controlled air in the house. Cold drafts from vents will increase your home’s energy bill.

Can Wasps Get Through Air Vents?

Wasps can get into vents if there is no backdraft damper installed or if the installed damper isn’t airtight. Once they nest in the vents, they can cause various problems that make the AC system malfunction.

Humane Way to Get Rid of Wasps and Other Insects in Vents

Wasps are irritating, aggressive, and even deadly when in the house and a chance to get rid of them is always welcome. People usually get rid of wasps by killing them using pesticides, swatting or pulling down their nests, and so on. These methods while easy, are inhumane and are unfriendly to the environment. We’re all about the environment here 🙂 

Wasps are beneficial to the ecosystem. They help with pollination and they are a natural way of controlling pests in your outdoor garden. If you are growing succulents, for example, you will want to keep wasps around to deal with white mites and other pests. Ordinary pesticides usually kill your succulents and this might be the motivation you need to keep wasps around and in one piece. 

It is important to get rid of wasps in your ventilation ducts but why do wasps get into vents and why is it important to remove them?

Vents provide a conducive environment for wasps to nest. They have the necessary space for the nest to be big enough to take all the wasps and eggs in a colony. The damp air extracted from the house provides water for the wasps so it is a perfect nesting location.

Here is how you can get rid of wasps inside ventilation ducts without hurting them

  • Turn on the exhaust fan at full speed
  • Every couple of hours spray a little bit of spearmint infused water into the duct*
  • Keep the fan running until the waps move out (usually, they will leave within 24 hours since they don’t like spearmint and the constant high airflow
  • install a quality backdraft damper close to the wall/roof vent cap to prevent them from moving back in

*You can use a few drops of essential oil in the spray bottle

Rayson Empty Spray Bottle, Frosted Assorted Colors

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