How to Easily Find the Air Filter for Your Home's HVAC System

Learn how to easily find and replace your home's HVAC system's air filter with these helpful tips from an HVAC professional.

How to Easily Find the Air Filter for Your Home's HVAC System

It can be tricky to locate the air filter in some air conditioning systems, but it's usually found in the return air duct. This is the big metal grille on the wall, floor, ceiling, or utility closet door. Return air ducts can be anywhere, and sometimes, especially with older systems, the filter is located inside the oven itself, next to the fan motor. In some cases, a central filter grille is installed on the wall or ceiling.

This grille opens up to reveal the air filter. The air filter is usually close to your home thermostat or near your air conditioning system's air controller. Larger homes may have more than one climate control system, and each of them will have at least one filter. First, look for filters inside or near the HVAC unit itself.

These filters are usually located next to the oven or air conditioning controller. The HVAC unit is often found in an attic, basement, or in the back of a closet. Once you've located the unit, look for a removable or hinged cover that's about one inch wide. It can be oriented horizontally or vertically, and you should find a filter that's already in place.

Many air conditioning systems or hot air handlers have one or more air filters that are installed within the fan assembly itself. By keeping your system running efficiently and without having to force air through clogged filters, you can save money on your monthly heating and air conditioning bills. The air filter may be in one or more common air returns or in the air controller, or less commonly, in a slot in the return air duct near the air controller. You may see household dust deposits around the edges of the opening where the air filter is mounted, indicating where the air shunt leaks.

Start by looking for a waste source near the central air return system; continue to look for leaks that could attract debris to the return air duct system anywhere along its length. Vertical air handlers can be an upflow unit that has return air that enters through the bottom of the unit and exits from the upper part of it. If your system has been operating in heating mode, then you'll notice that the air supply or outlet ends of the ducts connected to the air controller will be hot to touch and that the intake or return air ducts will be cooler.Someone may have added an additional intake (yellow arrows) to improve total airflow through the system; however, extracting return air that's located near a furnace's oil or gas burner may not be ideal. There should have been a metal divider that prevents significant intake if you only use a 1-inch filter.I recommend using a larger surface area filter that can work effectively for 3 months to a year before needing replacement.

I like having a filter on the intakes because it helps keep return ducts and fans clean; however, if you already have an appropriate filter in or on your air controller that should protect your fan, then you should be careful about adding more layers of filtration without consulting your HVAC company about your system's airflow rate requirements and any restrictions from additional filters.In almost all central cooling or heating systems, you'll find the fan at the return end of the system. It is usually found in the return air duct or in the fan compartment before it reaches the air controller.Using an appropriate filter can help keep your HVAC system running smoothly and efficiently while also saving you money on monthly heating and cooling bills. If you're having trouble locating your home's filter, contact an HVAC professional who can help you find it and replace it if necessary.