What Happens If You Don't Replace Your HVAC Filter?

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So winter is upon us, and that means you'll need your HVAC system in tip-top shape. And no, you don't need to cover your HVAC unit this winter; you just need to maintain it. For many people, HVAC maintenance is not a priority until the system fails and they are forced to repair it. But you don't need to wait until it's broken to make sure it still works fine. Replacing the filters is one way to avoid that extreme.

When these filters get clogged up and you fail to replace them, you run the risk of significantly impairing their performance or crippling the system entirely. It also poses a big health risk, as clogged filters prevent the system from decontaminating the air efficiently. Contaminants such as dirt, dust, and pet hair need to be filtered effectively to ensure excellent air quality. If that doesn't happen, you might notice it immediately with symptoms such as breathing difficulties, itchy eyes, and headaches.

The built-up dirt will also restrict airflow from the vents, making your home feel stuffier than usual. It can damage the temperature regulators, as the restricted airflow will result in poor, uneven heating or cooling. This, in turn, can increase your energy bill. You'll definitely want to keep your heat bill down this winter, and having the HVAC system labouring even harder to distribute the hot air isn't going to help. Then there's the risk of component damage, such as the evaporative coil that removes heat, clamping up due to an overload caused by a dirty filter.

How often should you replace your HVAC filter

Generally, you should change your HVAC filter once every one to three months, depending on various factors. These include whether you have pets, the type of filter you use, and the air quality in your home. Once you've passed the three-month mark, you start to risk some of the problems discussed earlier happening.

If you have the standard fiberglass filter, you can use it for up to two months before it needs to be replaced. This is because they use thinner filters that clog more quickly. With pleated filters, you can squeeze an extra month out of them since they are thicker and cover a larger area. Then there are the highly dense, high-grade, low-maintenance, high-efficiency HEPA filters. You find these in home air purifiers built to filter wildfire smoke, which is why they can last between six and 12 months.

This schedule is a good rule of thumb, but it can get more frequent. If your home is busy, exposed to dust and smoke, or receives little ventilation, the filters will clog up more quickly, since increased pollutants mean reduced efficiency over long periods. Fur, hair, and dander from pets contribute significantly to indoor air pollution, so you'll need to change the filters more frequently, regardless of which type you use — the more pets, the higher the frequency. Ultimately, you should inspect the filters from time to time.

How to inspect and change HVAC filters

Speaking of inspections, it is recommended that you check your HVAC filter once a month to monitor its performance. To do this, locate the filter and hold it up to the light. If it is not so discoloured and light passes through it, then it's still viable. But if it is gray or black rather than white, and light cannot pass through it, then it's clogged and ready to be replaced. That is, unless you have one of those washable, reusable filters, in which case, you will need to clean it.

To replace your HVAC filter, turn off the HVAC system and locate the filter compartment, which is always either at the top or bottom of the unit, depending on whether it's a downflow or upflow system. In an upflow system, the filter is at the bottom; in a downflow system, the filter is at the top. Once you find it, replace it with a new one.

To clean a reusable one, you also start by turning off the system, locating the filter compartment, and sliding it out. Then, soak it for a bit in a warm, soapy mixture, depending on how dirty it is. Once you've done this, wash the filter by scrubbing with a soft brush, cloth, or sponge. Be careful not to damage it in the process, or you'll need to replace it. Rinse it thoroughly, leave it to dry completely, and reinstall it.