Identify Correct Filter Size and Airflow Direction — Identify Filter Size and Type
Part of project
AC Filter Replacement · Step 4 of 8
In this video
Examine the old filter for printed dimensions, which usually indicate the nominal size (e.g., 20" x 20" x 1"). Also, look for the 'Actual Filter Size,' which may be slightly smaller (e.g., 19-3/4" x 19-3/4" x 7/8"). If the old filter is unreadable or missing, use a tape measure to determine the exact width, length, and depth of the filter slot in the housing. Next, locate the 'AIR FLOW' arrow printed on the new filter's cardboard frame. This arrow indicates the direction the air should flow through the filter. For ceiling-mounted returns, the arrow typically points upwards, towards the ductwork. For wall-mounted returns or filters located on the HVAC unit itself, the arrow should point towards the blower motor or into the system.
FAQs
How do I find the correct size and type of replacement filter?
The filter size is usually printed on the cardboard frame of your old filter (e.g., 20x25x1). Note down these dimensions before buying a new one, like the ACDelco Air Filter A2014C. For filter type, MERV ratings (Minimum Efficiency Reporting Value) indicate how effectively a filter cleans the air; consult your HVAC system's manual or a professional to choose the appropriate MERV rating for your system.
Can I clean my old AC filter instead of replacing it?
Most residential AC filters, especially disposable pleated or fiberglass types, are not designed to be cleaned and reused. Attempting to clean them can damage the filter media, reducing their effectiveness and potentially pushing debris into your HVAC system. Always replace disposable filters with new ones to maintain air quality and system health.
What are common mistakes people make when replacing an AC filter?
A common mistake is installing the new filter backward; always ensure the airflow arrow on the filter points in the direction of the furnace or air handler. Another error is forcing the wrong size filter into the slot, which can lead to air bypassing the filter and reducing efficiency. Always double-check the dimensions and the airflow direction arrow before installation.
What if I can't find the filter slot on my furnace or air handler?
The filter slot is usually located where the return air duct enters the furnace or air handler, often in a dedicated slot near the main unit. It might also be behind a return air vent grille in your ceiling or wall. If you're having trouble locating it, consult your HVAC system's manual or look for a hinged door or cover near the main unit where the large air duct connects.
Identify Correct Filter Size and Airflow Direction — Identify Filter Size and Type
Part of project
AC Filter Replacement · Step 4 of 8
In this video
Examine the old filter for printed dimensions, which usually indicate the nominal size (e.g., 20" x 20" x 1"). Also, look for the 'Actual Filter Size,' which may be slightly smaller (e.g., 19-3/4" x 19-3/4" x 7/8"). If the old filter is unreadable or missing, use a tape measure to determine the exact width, length, and depth of the filter slot in the housing. Next, locate the 'AIR FLOW' arrow printed on the new filter's cardboard frame. This arrow indicates the direction the air should flow through the filter. For ceiling-mounted returns, the arrow typically points upwards, towards the ductwork. For wall-mounted returns or filters located on the HVAC unit itself, the arrow should point towards the blower motor or into the system.
Frequently Asked Questions
How do I find the correct size and type of replacement filter?
The filter size is usually printed on the cardboard frame of your old filter (e.g., 20x25x1). Note down these dimensions before buying a new one, like the ACDelco Air Filter A2014C. For filter type, MERV ratings (Minimum Efficiency Reporting Value) indicate how effectively a filter cleans the air; consult your HVAC system's manual or a professional to choose the appropriate MERV rating for your system.
Can I clean my old AC filter instead of replacing it?
Most residential AC filters, especially disposable pleated or fiberglass types, are not designed to be cleaned and reused. Attempting to clean them can damage the filter media, reducing their effectiveness and potentially pushing debris into your HVAC system. Always replace disposable filters with new ones to maintain air quality and system health.
What are common mistakes people make when replacing an AC filter?
A common mistake is installing the new filter backward; always ensure the airflow arrow on the filter points in the direction of the furnace or air handler. Another error is forcing the wrong size filter into the slot, which can lead to air bypassing the filter and reducing efficiency. Always double-check the dimensions and the airflow direction arrow before installation.
What if I can't find the filter slot on my furnace or air handler?
The filter slot is usually located where the return air duct enters the furnace or air handler, often in a dedicated slot near the main unit. It might also be behind a return air vent grille in your ceiling or wall. If you're having trouble locating it, consult your HVAC system's manual or look for a hinged door or cover near the main unit where the large air duct connects.