Allergen* Plus HEPA Air Purifier for XL Rooms, White, HPA304

Our Allergen Plus HEPA Air Purifier for extra large rooms, helps capture airborne allergens* and particles, while helping provide cleaner, fresher air in extra large rooms up to 465 sq. ft².

  • HEPA Filtration: helps capture up to 99.97% of the following microscopic airborne allergens and particles: dust, pollen, pet dander, dust mite debris and smoke¹
  • Ideal for wildfire season: HEPA filtration helps capture wildfire smoke particles¹ that can infiltrate your home.
  • 3 Cleaning Levels + Turbo Mode
  • Quiet Performance
  • Filter Change Reminder Light
  • Auto-off Timer
¹ From the air that passes through the filter, 0.3 microns and larger
² Based on 3rd party independent CADR testing for the smoke CADR value when operated at the highest level. Air circulation depends on many factors, such as room size and configuration. There is no guarantee that all of the air in a room will pass through the filter.
*Non-living allergens


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Product details

Details & Dimensions

This Honeywell Allergen Plus HEPA Air Purifier console helps provide cleaner, fresher air in extra large rooms of 465 square feet. HEPA Filtration helps capture up to 99.97% of the following microscopic airborne allergens and particles: dust, pollen, pet dander, dust mite debris and smoke, from the air that passes through the filter, 0.3 microns and larger. An activated carbon pre-filter helps capture large airborne particles and reduces odors and VOCs. Independently tested and AHAM Verifide to circulate and filter the air in your room every 12.5 minutes in a 465 sq. ft room*

Model #: HPA304 (white) 
Room Size: Extra Large, up to 465 sq. ft.
Product Dimensions: 22.3″ H x 20.0″ L x 10.8″ W
Initial Filters included: 3 R HEPA Filters, 1 Odor Reducing A Pre-filter

*Based on 3rd party independent CADR testing for the smoke CADR value when operated at the highest level. Air circulation depends on many factors, such as room size and configuration. There is no guarantee that all of the air in a room will pass through the filter.
Compatible Replacement Filters

The Honeywell Allergen Plus HEPA Air Purifier for extra large rooms (model: HPA300) is compatible with the Honeywell HEPA R Replacement Filter, and A Pre-Filter.

It requires 3 Type R Certified HEPA Filters, which should be replaced once a year, and 1 Type A Odor Reducing Pre-filter, which should be replaced every 3 months.

These replacement filters can be purchased individually or as part of a value pack.

Owner's Manual & FAQs

Owner’s Manual: HEPA Air Purifiers – HPA 090/100/200/300 Series

Q: How do I change the filter on my Allergen Plus HEPA Air Purifier (HPA304)?

A: Remove the wrappers covering the filters and pre-filter. Make sure the air purifier is OFF and unplugged. Press the two hand symbols on the front grille to release it from the unit and pull the grille toward you to remove it. Grasp the sides of the filter frame near its top end and pull outward. Repeat for the second and third filter if applicable.

  • Remove protective wrap from the filters.
  • Place the Type R Certified HEPA Filters into the air purifier housing. Ensure that the removal “pull” tabs are facing outward (this will facilitate filter removal later). Place the Type A odor-reducing pre-filter on top of the HEPA filters. Tuck the edges of the pre-filter into the tabs that are located around the edges of where the HEPA filter(s) are inserted. Model HPA300 has velcro strips on the housing where the pre-filter should be attached.
  • Replace the front grille by placing the tabs on the bottom of the grille into the slot(s) on the unit. Gently push the top of the grille into place by pressing on the hand symbols to secure in place.

Q. What are VOCs?

A: Volatile Organic Compounds (VOCs) are emitted from various solids and liquids such as paints, cleaning supplies, building materials, and permanent markers.

For additional FAQ or post-purchase support, please visit our support page.

Warranty Information

5 Year Limited Warranty

What You’ll Need to Register Your Air Purifier:

  1. Model number for each product you purchased *
  2. An email address. We will use this to send you confirmation of your registration
  3. The purchase date of your product

Allergen Plus Series Filtration

R HEPA Filter

The HEPA Filtration of the R filter helps capture up to 99.97% of of microscopic airborne allergens & particles from the air that passes through the filter, 0.3 microns and larger. These include smoke, pollen, pet dander, dust and dust mite debris. 

A Pre-Filter

The A pre-filter helps reduce trash odors, bathroom odors and VOCs, circulating fresher air back into the room. 

Compatible Does Not Mean Comparable


For best performance, use only Genuine Honeywell air purifier filters. Compatible air purifier filter replacements are not guaranteed to offer the same performance or efficiency.


This model requires 3 HEPA R Filters and 1 A Pre-filter.