Why Most Vent Screens Made of Plastic or PVC Mesh May Not Be Safe

One of the biggest misconceptions people have, when it comes to protecting their high efficiency furnace, hot water heater or boiler vent pipes, is they can head over to Home Depot or Lowes and pick up an inexpensive plastic or PVC cover to protect their vents. The typical hardware store does not sell protective vent screens, caps or guards for high efficiency appliances. What these hardware stores sell are highly restrictive PVC floor drain covers and other items that are not properly suited for use on high efficiency appliance ventilation systems. In fact, some of these items are dangerously used during winter and are completely ineffective at preventing bees and wasps from nesting within high efficiency appliances or the PVC pipes themselves. For this reason, our company was founded on the principal to only manufacture and sell the best flowing protective vent screens as possible to protect critical ventilation systems from all seasonal threats. You can view all of our vent protection products in our store or watch a short video of how they work in our sizing guide. Besides maintaining industry leading airflow and protection, the superior materials used in manufacturing our vent screens far exceed standards for a variety of HVAC and plumbing applications. Because our vent screens are superior in both quality and airflow, our vent screens are used not just in homes, but in leading businesses, hospitals, OEM applications and publicly owned buildings of the US Government.

Furnace Exhaust Vent Accessed by AnimalMany home owners and building maintenance supervisors understand how important it is to caulk around windows and other voids outside of a home or business. Besides eliminating moisture and drafts, sealing exterior entry points into a dwelling can also prevent insects or animals from entering as well. It’s no surprise that many question why a HVAC or plumbing installer would caulk around PVC intake and exhaust termination pipes yet leave a large 2″, 3″ or 4″ diameter pipe opening unprotected. Consider yourself lucky if you are just contemplating the purchase of a vent protection product and not dealing with damage from vents that were left unprotected. For example, in the image to the right you will see an animal that entered a PVC furnace exhaust pipe and became lodged inside the furnace’s inducer motor housing. In many cases an animal that enters a home through a vent is not discovered until strange sounds are heard coming from the appliance when it is not running, a foul odor emanates from the appliance or because the boiler, furnace or hot water heater simply will not start. Yet there are other cases where chipmunks commonly bring seed into an unprotected exhaust vent pipe and the inducer motor attempts to grind the seeds up when the furnace receives a call for heat. In this case the grinding is often so loud that it can be heard throughout every level of the average home and easily tips off the occupants that there is a major problem. Insects also create a host of problems as well and are more likely to find their way into the actual living spaces of a home or business. When animals or insects enter an appliance the damage can be costly, in addition to the downtime and inconvenience caused by appliances that are out of service. Unfortunately, many of our customers only first learn of our company after they’ve experienced inducer motors damaged beyond repair that exceed $500 to replace or yellow jacket nests that cost even more to eradicate. Even ants that enter vents, as small as they may be, can be costly to remove if they attempt to colonize inside a high efficiency appliance. Though the need to protect vents is clear, there is a correct way to do it and the information you find on this page will help you better understand how to protect your ventilation system and why the vent screens we sell are superior.

Since the primary purpose of a PVC vent is to allow air, gas or water to enter or exit, protecting these vents must be done with the least amount of restriction as possible. Especially during winter, the flaws of inadequate airflow can be exposed and cause unintended consequences such as an unwanted appliance shutdown, known as a lockout. Worse yet, improper vent protection can ice over during below freezing temperatures and cause carbon monoxide to accumulate in dwellings and create an unsafe environment for the occupants. Since insect nests and animals lodged within PVC pipes can also cause similar safety concerns, a balanced and seasonal approach must be made to protecting vents. This balance is achieved with our PVS series vent screens, which provides best in class airflow to protect against all seasonal threats such as animals, debris and even insects. In designing our PVS series vent screens, we examined the flaws of other vent protection products to overcome their limitations and ultimately produced vent screens that not only exceeded our expectations but those of original equipment manufacturers (OEM) as well. Below we will discuss the limitations of improper vent protection products and the safety concerns the general public should consider when deciding which product is best to protect their vents.

Though we touched on the primary differences between real high efficiency appliance vent screens, caps and guards elsewhere on our website, we really want to do a better job of warning consumers about the pitfalls of using plastic and PVC vent pipe covers. Though plastic and PVC components are relatively inexpensive to produce, they have their limitations. For example, a .040” thick strand of stainless steel wire is much stronger than any plastic or PVC equivalent. Since plastic and PVC has very little strength at thin diameters, manufacturers must produce a mesh that is much thicker to gain additional strength. For a floor drain, as an example, this is not a major issue. But high efficiency furnaces, hot water heaters and boilers are more sensitive to what the mesh screens allow – airflow.

3" PVC GrilleIf you look to the image to the left, you will see 3″ PVC grille. In this grille, the PVC sections that separate the openings are actually thicker than the openings themselves. What you are looking at is a termination grille that will only permit an airflow rate of 40%. Such a substandard airflow reduces the efficiency of intake and exhaust vents, which could lead to lost efficiency in the appliance, unsafe operating conditions (carbon monoxide buildup) and an unwanted system lockout that causes the appliance to shut down. Additionally, these types of vent screens are incapable of keeping out insects. Our 3″ insect and rodent vent screen for high efficiency appliances, as an example, maintains an airflow rate of 70%.

PVC Floor Drain CoverIt’s not uncommon to see people selling vent caps, guards and other types of covers that are not intended for use on high efficiency appliances. This is common at places like eBay, where you can find a similar “vent guard” as the one pictured to the right. This is not a vent guard, but a snap-in floor drain cover! Though this cover is relatively strong, and can support an adult standing on it, the product does not provide the airflow that modern day high efficiency appliances require. People considering the installation of that cover in their furnace, hot water heater or boiler vents would be better of with our 3″ rodent screen (2″ and 4″ models are available too), which provides nearly double the rate of airflow.

If you are shopping for a rodent or insect screen for your condensing furnace, power vent hot water heater or high efficiency boiler, please be cautious when looking at vent screens made from PVC or plastic. Also, as a consumer, ask yourself why most of these plastic and PVC product retailers do not advertise how much airflow their products maintain. This should be a telltale sign, to most wise consumers, that they are hiding something. And they are. Most plastic and PVC mesh screens reduce a vent opening’s capacity by at least 40%.

In general, a mesh steel wire, plastic, PVC or any other material will reduce airflow by a minimum of 5% for every .010” of mesh thickness. Since plastic and PVC has very little strength when it is thin, many of the covers made of this material must use .080” mesh, which leaves the overall capacity of the product at just 60% of what an unobstructed vent would allow for. Most HVAC technicians, plumbers and pest control specialists understand that such a poor rate of airflow is unacceptable, as should everyone. That’s the reason why we created this page – so that consumers are warned about the airflow problems with most plastic, PVC and even steel vent covers. The truth is that saving a few dollars buying a cheap vent screen cover may not be so cheap if a hot water heater won’t operate or if the pipes freeze because of a furnace lockout occurring during winter when nobody is home.

You will find all of the vent screens in our store to be forthcoming with their associated airflow rate. Simply select the two, three or four inch screen you are interested in and click on the “specifications” tab to view the mesh size and rated airflow. Should you have any additional questions about our products, please view our FAQ page or contact us. We are here to help you protect your high efficiency appliance(s), with the best American made PVC vent screens available, by offering high-quality products that are specifically designed for furnace, hot water heater and boiler ventilation systems.

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