As an Amazon Associate I earn from qualifying purchases.Updated: March 27, 2026
The Furnace Filter in your Rheem RA20 is essential for trapping dust, dirt, and other airborne particles, preventing them from circulating through the heating system and into your living space. Over time, the filter becomes clogged and less effective, restricting airflow and potentially causing the furnace to overheat. Replacing the Furnace Filter regularly ensures clean air and efficient operation of your Rheem RA20.
Function: The Furnace Filter removes dust, pollen, pet dander, and other airborne particles from the air before it passes through the heating system.
Signs it needs replacing: Reduced airflow, increased energy bills, unusual noises from the furnace, and visible dirt accumulation on the filter.
OEM vs aftermarket: OEM (Original Equipment Manufacturer) parts are specifically designed for your Rheem RA20, but they may be more expensive. Aftermarket filters offer a cost-effective alternative, with many options compatible with your model. Check reviews to ensure proper fit.
Installation: Replacing the Furnace Filter is typically straightforward and involves simply sliding out the old filter and inserting a new one in the same direction. Consult your Rheem RA20 user manual for specific instructions.
Replacement schedule: every 1 month
Compatibility warning: always verify part number matches your exact model before ordering
Pros & Cons
Pros
✓ Restores device to original performance without buying a new unit
✓ Significantly cheaper than a full device replacement
✓ Multiple options available from OEM and aftermarket sellers
Cons
✗ OEM parts cost more than third-party alternatives
✗ Wrong part number will not fit — model verification is essential
Common Use Cases
Scheduled maintenance on the every 1 month replacement cycle
Performance restoration after noticing reduced output or efficiency
Preventive replacement before a worn part causes secondary damage
Who Should Buy This
This Furnace Filter replacement is for owners of a Rheem RA20 (RA20036) whose furnace is experiencing reduced efficiency or airflow issues due to a worn filter. Replacing the filter can extend the life of your heating system and improve indoor air quality.
Not ideal for: If your Rheem RA20 is experiencing major malfunctions beyond a dirty filter, full device replacement may be necessary.
Good to Know Before Buying
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Always confirm your exact model number (RA20036) before ordering. Part numbers vary between model variants and production years. Check the label on your device or original documentation to be sure.
Frequently Asked Questions
What is the part number for the Rheem RA20 Furnace Filter?
The part number is RHEEM-1500M. Always verify this matches your exact model (RA20036) before ordering, as similar models may use different parts.
How often should I replace the Furnace Filter on my Rheem RA20?
every 1 month
Will aftermarket Furnace Filter replacements work in my Rheem RA20?
Third-party parts are widely available and often cheaper than OEM. Look for listings that specifically mention compatibility with model RA20036 and check buyer reviews for fit confirmation before purchasing.
Prices change frequently. See the latest deal on Amazon.