Many consumers have reached out to us when the encountered problems with cheap push-in style vent screens. As with most products, consumers tend to get what they pay for and vent screens are no different. On this page we will discuss the problems with push-in style vent screens and how to resolve them with PVS series vent screens sold in our store.

As you will see in this picture of a recently installed furnace exhaust vent, a wasp has already built a nest on the inside of the vent screen. These screens, which are often advertised as providing protection from large insects (including bees and wasps), actually help to shield bee and wasp nests from being disturbed. In addition to buildings nests right on the screen, bees and wasps will also go well beyond the screen and even nest inside an intake or exhaust vent pipe. Worse yet, bees and wasps may build their nests inside a furnace cabinet and find their way into the dwelling. Regardless of their inability to protect vents from insects, these push-in style vent screens offer poor airflow (typically less than 80%) when unobstructed and are commonly blamed for icing over during winter and causing furnace lockouts. With the small nest on the screen pictured to your left, airflow has been reduced to approximately 68%. If left unresolved during winter, when condensate freezes on the wires, additional airflow restrictions would likely reduce the available open area for the exhaust to approximately 55%.

Poor airflow is the leading reason for pressure and limit switch furnace lockouts. During winter we recommend using our PVS-RS series vent screen which offers 90% airflow. Cold dense air is easily drawn into the intake and what little condensate freezes on the exhaust screen wires will melt during the next call for heat. However, during the warmer months bees and wasps pass through rodent screens and often build nests inside ventilation pipes which also may cause restrictions that impact the performance of the appliance. For this reason, our PVS-IS series vent screen should be used during spring, summer and fall when insects are active. As you will see in the picture to the right, we made the exhaust vent termination pictured above “insect proof” by removing the cheap push-in style vent screen and replaced it with our PVS-IS2 vent screen. With the PVS-IS2 installed, this home owner no longer needs to worry about bees and wasps entering his furnace’s exhaust vent. Once a couple hard frosts hit in late fall, which eliminates the threat of insects, he can install the PVS-RS2 for winter. Combined, both the PVS-IS2 and PVS-RS2 are part of a complete all-season vent protection program for 2″ PVC vent terminations with an inside diameter of 2-3/8″. 3″ PVS series vent screens are also available in our store which fit inside 3″ vent termination hubs having a 3-1/2″ inside diameter.

If you would like to see how we removed and replaced a cheap push-in style vent screen with an upgraded PVS-IS2 vent screen, please watch the video below.

As you can see in the video above, our PVS series vent screens are quite easy to install. Because we use a stainless steel internal wire clip to hold our vent screens securely in place, serviceability is maintained without the need for any tools. Being able to install and remove our vent screens is important to address the seasonal threats to ventilation systems. As noted previously, for optimal protection our PVS-IS series vent screens should be used when insects are active and the PVS-RS series vent screens should be used when temperatures are below freezing and throughout winter.

Damage Caused by Push-In Vent Screens

Another problem with push-in style vent screen discs is that they scrape the inside of the PVC vent termination hub when they are installed and removed. In the image to your left you can witness such damage. Since the screen diameter is slightly larger than the vent termination hub, secured by a press fit, push-in style vent screens scrape the plastic until they seat against the inner flange. The shavings created from installing one of these vent screens can be pulled in through the intake and directly into the furnace cabinet where it may melt. Though rare, the damage caused by repeatedly installing and removing push-in style vent screens may necessitate the need to replace the vent termination hub by cutting it off and replacing it.

Push-In Vent Screens are Not Serviceable

Push-in style vent screen discs are not serviceable. As noted above, removing and reinstalling these types of vent screens will damage the vent termination hub. However, this type of vent screen also bends and becomes distorted on removal. These distortions often make reinstalling the screen difficult as it must be bent back to its original shape. Repeatedly bending the screens may also damage or break the welds on the wires, which leaves portions of the screen loose or unable to conform to the inside diameter of the vent termination hub and stay in place. In the picture to the right you can witness these distortions on the push-in style vent screen we removed in the video above.

Conclusion

As most licensed HVAC technicians will confirm, push-in style vent screens are not suitable for ventilation systems that involve combustion. Push-in style vent screens not only offer very limited protection from insects, being limited to very large insects such as butterflies, cicadas, etc., but they also are too restrictive for use during the winter which can impact the appliance efficiency and/or result in system lockouts. For optimal protection, we recommend viewing our best practices page to safeguard furnace intake and/or exhaust vents during all seasons.