Air Filters

HVAC Air Filters and Replacement Filter Products

Air filters help protect HVAC equipment by capturing dust, lint, debris, and airborne particles before they move through the furnace, air handler, heat pump, air conditioner, ERV, or indoor air quality system. The correct replacement filter can support airflow, help keep internal components cleaner, and assist with routine heating and cooling system maintenance.

Furnace Part Source carries HVAC air filters, air handler filters, furnace filters, heat pump filters, prefilters, filter pads, HEPA replacement filters, ERV filters, antimicrobial filters, disposable filters, and related filter products for residential, light-commercial, and commercial HVAC applications.

Common Air Filter Products We Carry

Common replacement air filter products include:

• Furnace filters for forced-air heating systems and central HVAC equipment.
• Air handler filters for indoor air handlers, attic air handlers, blower cabinets, and return-side filter slots.
• Heat pump air filters for systems that use the same indoor air handler for heating and cooling airflow.
• Prefilters for capturing larger particles before air reaches the main filter or indoor air quality component.
• Filter pads for compatible HVAC, humidifier, or equipment-specific filtration applications.
• HEPA replacement filters for compatible filtration systems that require a specific replacement filter.
• MERV-rated filters for systems that require a listed filtration level, such as MERV 13 ERV filters.
• Commercial and industrial HVAC filters for select equipment, ventilation systems, and replacement filter applications.

How to Choose the Right HVAC Air Filter

The best way to choose a replacement air filter is to match the existing filter or equipment requirements as closely as possible. Air filters can vary by size, thickness, MERV rating, frame style, airflow direction, pressure drop, and system compatibility. A filter that is the wrong size or too restrictive for the system may reduce airflow or fail to fit the filter cabinet correctly.

Before ordering, compare:

• Filter length, width, and thickness
• Brand and part number from the existing filter
• Furnace, air handler, heat pump, ERV, or HVAC model number
• MERV rating or filtration level required by the equipment
• Airflow direction arrow on the filter frame
• Filter cabinet, return grille, or air handler filter slot size
• Pressure drop or low-pressure HVAC filter requirements
• Disposable, washable, pleated, pad, HEPA, prefilter, or specialty filter type

If the old filter is available, check the size printed on the filter frame and compare it with the product listing. If the filter is missing, check the equipment manual, filter cabinet, return grille, or air handler model information before ordering.

Air Handler, Furnace, and Heat Pump Filter Fitment

Air filters may be located in several places depending on the HVAC system. Common locations include the return air grille, furnace filter slot, air handler cabinet, blower compartment area, filter rack, or return-side ductwork. Some attic air handlers and heat pump systems use filters at the return grille or inside the air handler access panel.

For heat pump systems, the same indoor air handler often moves air during both heating and cooling operation. That makes filter fitment and airflow important throughout the year. Always install the filter in the correct direction and make sure it sits securely in the filter slot without gaps around the frame.

MERV Rating, Airflow, and Low-Pressure HVAC Filters

MERV rating describes a filter’s particle capture performance, but a higher MERV rating is not automatically the right choice for every HVAC system. Some systems require a filter that balances filtration with airflow and acceptable pressure drop. If the filter is too restrictive for the blower and duct system, it may reduce airflow and affect equipment performance.

If you are searching for a low pressure HVAC filter, check the product details for airflow resistance, filter thickness, MERV rating, and equipment compatibility. When in doubt, follow the HVAC manufacturer’s filter recommendation or ask a qualified technician before changing to a more restrictive filter type.

Replacement Filters by Brand and Application

Furnace Part Source carries replacement filter products for a range of HVAC and indoor air quality brands. Available products may include Carrier air filters and prefilters, Lennox filter pads, Mitsubishi Electric filters, Honeywell HEPA replacement filters, Rheem-Ruud filter products, Broan-NuTone ERV filters, Friedrich antimicrobial filters, Bard HVAC filters, and other brand-specific replacement filters.

Brand name alone is not always enough to confirm fit. Many manufacturers offer multiple filter sizes, cabinet types, and replacement filter numbers across different equipment models. Use the part number, filter dimensions, and equipment model number to confirm the correct replacement before ordering.

When to Replace an HVAC Air Filter

Replacement timing depends on the filter type, system run time, indoor conditions, dust levels, pets, building use, and manufacturer guidance. Some disposable filters are replaced more frequently, while specialty filters, HEPA filters, filter pads, or equipment-specific filters may follow a different service schedule.

Check the filter regularly and replace it when it is dirty, damaged, collapsed, clogged, or past the recommended service interval. A dirty or incorrect filter can restrict airflow and may allow dust or debris to collect inside the HVAC system.

Need Help Finding the Right Air Filter?

Not sure which HVAC air filter, air handler filter, furnace filter, heat pump filter, prefilter, or replacement filter pad you need? Gather the existing filter size, part number, equipment brand, model number, and photos of the filter cabinet or old filter label before ordering.

You can also contact Furnace Part Source for help narrowing your options. Product details such as filter dimensions, MERV rating, equipment type, brand, and installation location can make it easier to identify the correct replacement filter.

Air Filter FAQs