Description
Product Overview
The HFAS100950-1-27x35x0.875 is a 27x35x0.875 washable MERV 4 foam air filter manufactured to AMFCO HF Series specifications for permanent, reusable installation in commercial, residential, and light industrial HVAC systems where reliable particulate filtration at low air resistance is required. Employing a two-stage progressive density MERV 4 foam media pack, the HFAS100950-1-27x35x0.875 first passes incoming air through a stage 1 aluminum mesh foam prefilter prefilter—an expanded aluminum grid combined with corrugated aluminum screen wire in a criss-cross pattern—that captures larger airborne particulate before directing the pre-filtered air through a stage 2 layer of 25 ppi open-cell polyurethane foam air filter media that captures smaller particles. Rated MERV 4, the HFAS100950-1-27x35x0.875 delivers 75% at rated airflow (300 fpm) dust arrestance efficiency with 24 grams per square foot dust holding capacity at rated 300 fpm airflow per the AMFCO HF Series independent test report.
Constructed with a precision-formed .030” thick aluminum frame with mitered corners secured with pop rivets and drain holes in three corners, the HFAS100950-1-27x35x0.875 maintains its critical 27.0” H × 35.0” W face dimensions within ±1/8” throughout its service life. With actual dimensions of 27.0” H × 35.0” W × 7/8″ D, this filter installs precisely in standard 27x35x0.875 nominal HVAC MERV 4 foam air filter housings. The two-stage media pack—aluminum mesh foam prefilter prefilter stage followed by 25 ppi open-cell polyurethane foam stage, backed by an expanded aluminum support grid on the air-exit side—delivers progressive density filtration that removes larger particles in stage 1 before they can load the foam in stage 2, extending filter service life between wash cycles.
Unlike adhesive-coated panel filters that must be discarded when fully loaded, the HFAS100950-1-27x35x0.875 captures particles mechanically and can be washed repeatedly with warm water to restore full filtration performance—no replacement media required, no recurring media cost. The HF Series MERV 4 foam air filter’s exceptionally low air resistance at rated 300 fpm makes it suitable for electronics cooling and computer room air filter systems, computer rooms, and other airflow-sensitive applications where excessive pressure drop would reduce cooling effectiveness, stress blower motors, or degrade temperature control. The 250°F maximum continuous operating temperature covers demanding commercial HVAC applications with elevated supply air temperatures.
Two important care requirements specific to the HF Series MERV 4 foam air filter: first, do NOT coat the HFAS100950-1-27x35x0.875 with any adhesive—the manufacturer specifically states that adhesive coating is not advisable for this filter type. Second, do NOT expose the HFAS100950-1-27x35x0.875 to direct sunlight or ultraviolet light—UV exposure degrades the polyurethane foam media over time. Store and install away from UV sources. Installation is flexible: the filter may be mounted vertically or horizontally with no required directional orientation, providing simple fitment in a wide range of HVAC housing configurations. The HFAS100950-1-27x35x0.875 is manufactured by American Metal Filter Company (AMFCO) and is UL Classified 900.
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Key Benefits of the HFAS100950-1-27x35x0.875 MERV 4 Foam Air Filter
- MERV 4 Rated — Two-Stage Dust Arrestance: Independently tested and verified at MERV 4 efficiency, the HFAS100950-1-27x35x0.875 delivers consistent dust and airborne particulate filtration across the recommended 250–350 fpm airflow range. The two-stage progressive density media pack captures particles mechanically through both the aluminum mesh prefilter stage and the 25 ppi open-cell polyurethane foam stage, providing higher overall efficiency than single-stage all-metal washable filters
- Two-Stage Progressive Density Media: Stage 1 uses expanded aluminum grid (corrugated) plus corrugated aluminum screen wire in a criss-cross configuration to capture large airborne particles and pre-condition the airstream. Stage 2 uses 25 ppi open-cell polyurethane foam to capture smaller particles that passed through stage 1. This progressive approach protects the foam from rapid loading by large particles, extending time between wash cycles
- Low Air Resistance — Suitable for Electronics: The HF Series MERV 4 foam air filter’s open-cell foam construction maintains low static pressure drop at rated 300 fpm, making the HFAS100950-1-27x35x0.875 appropriate for applications where excessive filter resistance would reduce cooling airflow, stress blower motors, or degrade temperature control—including computer rooms, server areas, electronic equipment enclosures, and other airflow-sensitive installations
- Permanent washable MERV 4 foam filter design: Rinse with warm water to restore full filtration performance—no replacement media required. The HFAS100950-1-27x35x0.875 eliminates the recurring cost and procurement burden of disposable filter programs while delivering consistent MERV 4 particulate filtration throughout years of residential, commercial, and industrial HVAC service
- 250°F Maximum Operating Temperature: Rated for continuous operation at temperatures up to 250°F, covering the requirements of commercial air handlers, industrial ventilation systems, and HVAC applications with elevated supply air temperatures where standard foam or electrostatic filters would be damaged or degraded
- All-Aluminum Frame Construction: .030” thick aluminum frame with precision-mitered corners, pop-rivet construction, and drain holes in three corners provides structural rigidity and corrosion resistance across years of washing cycles and HVAC service. The all-aluminum construction maintains the critical 27.0” × 35.0” face dimensions within ±1/8” tolerance throughout the filter’s service lifetime
- Flexible Installation — Vertical or Horizontal: The HFAS100950-1-27x35x0.875 may be installed vertically or horizontally without any orientation restriction, simplifying installation in diverse HVAC housing configurations. Unlike moisture separator filters requiring strict upright mounting, the HF Series MERV 4 foam air filter delivers full filtration performance in either orientation
- No Adhesive Coating Needed or Recommended: The two-stage foam and aluminum mesh construction provides effective particulate capture without adhesive coating. AMFCO specifically states that coating the HF Series filter with adhesive is not advisable—no Filter Coat, tackifier, or other adhesive treatment should be applied
- Made in USA by AMFCO — UL Classified 900: Manufactured by American Metal Filter Company with precision quality control ensuring consistent dimensional accuracy, proper fitment in standard HVAC housings, and reliable MERV 4 filtration performance throughout years of commercial and industrial service
Technical Specifications
The HFAS100950-1-27x35x0.875 27x35x0.875 MERV 4 foam air filter delivers verified performance specifications for particulate filtration in commercial, residential, and light industrial HVAC applications. All specifications conform to the authoritative AMFCO HF Series Tech Sheet and independent test report. The comprehensive data below covers every dimension, material, and performance parameter required for HVAC system design, procurement specifications, facility maintenance documentation, and regulatory compliance records.
| Specifications: | Details: |
|---|---|
| Model Number | HFAS100950-1-27x35x0.875 (HF Series — Two-Stage washable MERV 4 foam air filter) |
| Nominal Size | 27” × 35” × 0.875” |
| Actual Dimensions | 27.0” H × 35.0” W × 7/8″ D (±1/8” H&W, ±1/16” depth) |
| Frame Material | .030” thick aluminum |
| Frame Construction | Precision-mitered corners secured with pop rivets; drain holes in three corners |
| Stage 1 Media | Expanded aluminum grid (corrugated) + corrugated aluminum screen wire (criss-cross) — captures large airborne particulate |
| Stage 2 Media | 25 ppi open-cell polyurethane filter foam — captures fine airborne particulate |
| Foam Porosity Tolerance | ±5 ppi (nominal 25 ppi) |
| Exit Support Grid | Expanded aluminum support grid on air-exit side |
| Filter Type | Two-stage impingement type washable foam and aluminum panel filter |
| MERV Rating | MERV 4 |
| Dust Arrestance | 75% at rated airflow (300 fpm) (ASHRAE 52.1) |
| Dust Holding Capacity | 24 grams per square foot |
| Rated Airflow | 300 fpm face velocity |
| Recommended Airflow Range | 250–350 fpm |
| Maximum Operating Temperature | 250°F continuous |
| Recommended Final Resistance | 0.50 inches W.G. before cleaning |
| Cleaning Method | Rinse with moderate-to-heavy stream of warm water; air dry before reinstalling |
| Adhesive Coating | NOT advisable — do not coat this filter with any adhesive coating |
| UV / Sunlight Warning | DO NOT place in direct sunlight or UV light — degrades polyurethane foam media |
| Installation Orientation | Vertical or horizontal — no orientation restriction |
| Drain Holes | In three corners of frame (structural drainage — not for moisture separation) |
| Washability | Frequent and moderate |
| Filter Weight | 3.02 lbs |
| Compliance & Certifications | UL Classified 900 |
| UPC Code | 840373523214 |
| GTIN Code | 00840373523214 |
| Country of Origin | Made in USA |
Commercial & Residential Applications
The HFAS100950-1-27x35x0.875 27x35x0.875 MERV 4 foam air filter delivers reliable particulate filtration across residential, commercial, and light industrial environments where permanent washable filtration is preferred over disposable media replacement. The two-stage aluminum mesh and foam construction, 250°F temperature rating, low air resistance, and all-aluminum corrosion resistance make this filter suitable for a broad range of HVAC applications where MERV 4 efficiency, washability, and long service life are required.
General HVAC Filtration — Residential and Light Commercial
Standard residential and light commercial HVAC systems benefit from the HFAS100950-1-27x35x0.875’s combination of MERV 4 particulate efficiency, low static pressure drop, and permanent washable construction. Installed in standard 27x35x0.875 nominal filter positions in residential air handlers, heat pumps, package units, and light commercial rooftop systems, the HFAS100950-1-27x35x0.875 captures household dust, pet dander, pollen, lint, and larger airborne particulate at 75% or 85.4% arrestance efficiency (depending on depth) while maintaining the low resistance that residential blower motors require for energy efficiency and airflow balance. The permanent design eliminates monthly or quarterly filter replacement costs that accumulate over years of HVAC operation—washing the HFAS100950-1-27x35x0.875 with warm water restores full filtration performance without replacement media expense. Buildings with occupants who prefer a maintenance-focused approach to HVAC filtration rather than disposable filter replacement programs find the HF Series foam filter an economical long-term alternative to monthly throwaway filters.
Electronics Cooling and Computer Room Applications
Electronic equipment cooling systems, server rooms, computer labs, and data processing facilities often use forced-air cooling with HVAC-style panel filters to capture dust that can accumulate on circuit boards, heat sinks, and cooling fans over time. Dust accumulation on electronics causes thermal resistance that leads to overheating, premature component failure, and data loss in critical systems. The HFAS100950-1-27x35x0.875’s HF Series foam filter design is explicitly recognized by AMFCO as suited for “computers and electronic equipment requiring dust particle filtration” and “low airflow HVAC applications.” The low static pressure drop maintains cooling airflow volume essential for electronics thermal management, and the mechanical particulate capture mechanism requires no adhesive (adhesive-coated filters are not recommended for the HF Series). The washable and reusable washable foam air filter design simplifies filter maintenance in data center environments where filter replacement logistics create operational burden. Installed in standard 27x35x0.875 nominal positions in computer room air conditioning (CRAC) units, precision cooling units, or supplemental cooling systems, the HFAS100950-1-27x35x0.875 provides effective long-term dust protection without the recurring cost of disposable filter replacement programs.
Commercial Air Handlers and Mechanical Rooms
Commercial HVAC systems in office buildings, retail facilities, healthcare outpatient spaces, and institutional buildings use standard-sized panel filters as pre-filters or primary filtration in air handling units. The HFAS100950-1-27x35x0.875 installs in standard 27x35x0.875 nominal filter banks in air handling unit filter sections, providing MERV 4 primary filtration that captures visible dust, lint, and larger particulate before it can load downstream coils, fan blades, and ductwork. Commercial building operators who prefer permanent washable filters over disposable media programs find the HFAS100950-1-27x35x0.875 provides a consistent MERV 4 filtration solution with no recurring replacement media cost—quarterly filter inspection and washing when loaded restores full performance. The 250°F temperature rating accommodates commercial air handlers that supply heated air to building spaces, and the all-aluminum construction maintains dimensional accuracy and corrosion resistance through years of commercial service with frequent washing cycles.
Light Industrial and Process Ventilation
Light industrial facilities with general manufacturing ventilation, assembly area air quality control, machinery cooling ventilation, and clean room pre-filtration applications benefit from the HFAS100950-1-27x35x0.875’s combination of washable construction, mechanical particulate capture, and resistance to industrial cleaning procedures. AMFCO lists “machinery ventilation foam air filter” and “air cleaners requiring a permanent MERV 4 dust filtration foam filter solution” as primary HF Series applications. The HFAS100950-1-27x35x0.875’s aluminum construction resists corrosion from elevated humidity in industrial environments, and the washable foam and mesh design handles the frequent cleaning cycles required by high-particulate industrial operations. Unlike adhesive-coated metal filters that lose effectiveness after each cleaning and require recoating, the HFAS100950-1-27x35x0.875 foam media restores full mechanical capture efficiency with each warm-water rinse without any re-treatment. The 250°F temperature rating accommodates heat-generating industrial processes where inlet air temperatures exceed residential HVAC ranges.
Construction Features
The HFAS100950-1-27x35x0.875 27x35x0.875 MERV 4 foam air filter represents engineered construction optimized for decades of reliable MERV 4 particulate filtration foam air filter performance across thousands of wash cycles. Every component is specified to deliver consistent two-stage MERV 4 foam and aluminum mesh filtration, structural durability, corrosion resistance, and complete washability—from the precision-mitered aluminum frame to the progressive density two-stage media pack and expanded aluminum exit support grid.
Aluminum Frame with Mitered Corners
The precision-formed .030” thick aluminum perimeter frame provides structural rigidity for the 27x35x0.875 filter while maintaining the critical 27.0” × 35.0” face dimensions within ±1/8” tolerance across years of service. Pop-rivet corner construction at precision-mitered 45-degree joints creates true square corners essential for proper fitment in standard HVAC MERV 4 foam air filter housings without air bypass gaps around the frame perimeter. The all-aluminum construction resists corrosion from humidity, condensation, and the warm-water washing procedure without the frame degradation that affects lower-quality steel or cardboard-framed alternatives. Drain holes in three corners of the frame provide drainage for residual wash water during the cleaning procedure and any condensation that may accumulate in the filter section during HVAC operation. Note that these drain holes are structural drainage features—the HF Series foam filter is not a moisture separator and does not require drainage orientation during installation.
Stage 1: Aluminum Mesh Prefilter
The first stage of the HF Series two-stage media pack consists of an expanded aluminum grid corrugated to increase surface area, combined with layers of corrugated aluminum screen wire assembled in a criss-cross pattern for structural strength. This aluminum mesh prefilter stage captures larger airborne particulate—dust, lint, pet hair, pollen, coarse dust particles—before the airstream reaches the second foam stage. By removing larger particles in stage 1, the aluminum mesh protects the 25 ppi open-cell polyurethane foam from rapid loading with coarse material that would otherwise quickly increase static resistance and reduce filter service life between wash cycles. The corrugated aluminum screen wire in the criss-cross configuration provides mechanical strength that maintains filter geometry under the airflow forces experienced at rated 300 fpm, preventing media collapse or shifting that would create bypass channels. The aluminum wire construction resists corrosion from humidity and washing, maintaining structural integrity throughout the filter’s service life.
Stage 2: 25 ppi Polyurethane Filter Foam
The second stage of the HF Series media pack is open-cell polyurethane foam with a nominal porosity of 25 pores per inch (ppi), with ±5 ppi manufacturing tolerance. This 25 ppi foam grade provides the combination of particle capture efficiency and low air resistance that characterizes the HF Series filter. The open-cell foam structure captures airborne particulate through mechanical interception and inertial impaction as particles in the pre-filtered airstream attempt to navigate the foam cell geometry at rated 300 fpm velocity—particles larger than the cell openings are intercepted; smaller particles that change direction at foam cell surfaces are captured by impaction. The 25 ppi foam density achieves the MERV 4 rated efficiency (75% arrestance for 7/8″ depth) while maintaining low static pressure drop essential for electronics and airflow-sensitive applications.
Critical Care: Do NOT coat the foam stage with any adhesive. AMFCO explicitly states that coating the HF Series filter with adhesive is not advisable. Additionally, do NOT expose the filter to direct sunlight or ultraviolet light, which degrades polyurethane foam media over time. Store and install the HFAS100950-1-27x35x0.875 away from UV sources including skylights and windows with direct sun exposure.
Exit Support Grid
An expanded aluminum support grid on the air-exit side of the HFAS100950-1-27x35x0.875 supports the two-stage media pack against airflow pressure forces at rated 300 fpm, preventing media deflection or downstream displacement during HVAC operation. The expanded metal grid pattern allows unrestricted airflow through the filter face while providing distributed support points across the entire filter area. Aluminum construction matches the frame and stage 1 mesh materials for consistent corrosion resistance and dimensional stability through years of washing cycles and HVAC service.
Maintenance & Cleaning
The HFAS100950-1-27x35x0.875 27x35x0.875 MERV 4 foam air filter requires periodic washing to maintain optimal particulate filtration performance and restore the two-stage aluminum mesh and 25 ppi foam media pack’s capture efficiency. The washing process is straightforward—requiring only access to warm running water—and the AMFCO tech sheet specifies “frequent and moderate” washability for the HFA foam model. Regular washing removes accumulated dust and particulate from both the aluminum mesh prefilter stage and the foam stage, restoring the open-cell foam structure’s particle capture efficiency and maintaining low static pressure drop.
Washing Procedure
Remove the HFAS100950-1-27x35x0.875 filter from your HVAC system by sliding it out of the filter housing or releasing any retention hardware. Take the filter to a utility sink, hose bib, or outdoor washing area with access to warm running water. Hold the filter with the dirty (air-inlet) face directed away from you and rinse with a moderate-to-heavy stream of warm water from the clean side through to the dirty side, allowing water pressure to carry accumulated dust and particulate out through the loaded face. Continue rinsing until water runs completely clear through the foam media. For particularly loaded filters, allow a brief soak period with warm water before rinsing.
Important: High-powered steam cleaning is unnecessary and not recommended. Chemical dips are unnecessary and not recommended. Vigorous scrubbing that deforms the aluminum mesh stage should be avoided. After washing, shake off excess water and allow the filter to air dry completely before reinstalling in moisture-sensitive HVAC applications, or reinstall with residual moisture in systems where some initial moisture is acceptable.
Critical Care Reminders
Do NOT apply adhesive coating to the HFAS100950-1-27x35x0.875 after washing or at any time during service. AMFCO explicitly states that adhesive coating is not advisable for the HF Series foam filter. The mechanical capture mechanism of the two-stage media does not require adhesive enhancement, and adhesive coating can clog the 25 ppi foam cell structure, increase static resistance, and impede subsequent washing.
Do NOT expose to UV light or sunlight. After washing, dry and store the HFAS100950-1-27x35x0.875 away from direct sunlight and UV light sources. Ultraviolet light degrades the polyurethane foam media over time, causing foam breakdown, reduced filter efficiency, and potential media fragmentation. Indoor storage away from windows and UV sources preserves the foam media’s filtration performance throughout its service life.
Washing Frequency Guidelines
The HFA is rated for “frequent and moderate” washing. Washing frequency depends on your application, particulate loading, and observed filter condition. General HVAC applications in normal residential or commercial environments typically require washing every 1–3 months. Electronics and computer room cooling applications with lower dust loads may require washing every 3–6 months. Industrial and machinery ventilation applications with higher particulate loads may require monthly or more frequent washing. Visual inspection is the most reliable indicator: when the aluminum mesh prefilter stage appears visibly loaded with dust or the foam stage appears discolored and compressed, washing is warranted regardless of elapsed time. Systems with differential pressure monitoring can use filter pressure drop rise above clean-filter baseline as an objective washing trigger.
Installation
Installing the HFAS100950-1-27x35x0.875 27x35x0.875 MERV 4 foam air filter follows standard HVAC panel filter installation procedures. Unlike moisture separator filters that require specific orientation for drainage, the HFAS100950-1-27x35x0.875 may be installed vertically or horizontally in any orientation that fits your housing configuration—no directional label must face a specific direction.
Pre-Installation Checklist
Before installing the HFAS100950-1-27x35x0.875, verify that your filter housing accepts 27x35x0.875 nominal size filters with actual interior dimensions accommodating the 27.0” H × 35.0” W × 7/8″ D filter within ±1/8” tolerance. Confirm your HVAC system operating temperature does not exceed 250°F at the filter location. Confirm the filter housing location is not exposed to direct sunlight or UV light—if the housing is in a location with UV exposure (near a skylight, window, or outdoor installation), take steps to shield the filter from UV radiation. Verify the filter housing is not in a location with adhesive overspray or chemical vapor that could contact the foam media. Clean the filter housing interior of accumulated dust and debris from previous filter service.
Installation Steps
Shut down your HVAC system before accessing the filter compartment. Remove any existing filter from the housing. Clean the filter housing interior using a vacuum or damp cloth. Insert the HFAS100950-1-27x35x0.875 into the housing in either vertical or horizontal orientation—no TOP label or directional orientation is required. Press the filter firmly into place ensuring all four edges of the aluminum frame seat properly against the housing walls with no air bypass gaps around the frame perimeter. Secure the filter using the housing’s retention mechanism per your specific system design. Close and secure the filter access door or panel. Restore power and restart the HVAC system. Record the installation date in your maintenance log for tracking wash intervals.
UV Exposure Caution
If your filter housing or filter storage location is subject to any direct sunlight or UV light exposure, take measures to shield the HFAS100950-1-27x35x0.875 from UV radiation. This includes filter housings near skylights, air handling units with transparent panels, outdoor equipment with sun-exposed filter sections, and storage locations near windows. UV light degrades the polyurethane foam media over time even when the filter is not in service—store unused filters indoors away from UV sources.
Complementary Products
Metal Air Filters offers a complete range of washable and permanent washable foam air filter solutions for applications with different performance requirements, temperature ratings, and filtration strategies. The HFAS100950-1-27x35x0.875 delivers MERV 4 particulate filtration with low air resistance; the following products address adjacent application requirements.
HM Series Aluminum Mist Eliminator Filters
For applications requiring moisture separation, water droplet capture, or oil mist elimination rather than dust filtration—such as outside air intakes, chilled water coil protection, and coolant mist applications:
• 12x24x1 Aluminum Mist Eliminator Filter (HMA101224) — 99%+ efficient on 3-micron water droplets; 500 fpm rated; 275°F max; impingement-type moisture separator with passive gravity drainage
• 20x20x2 Aluminum Mist Eliminator Filter (HMA202020) — HM Series 2-inch aluminum moisture separator for commercial HVAC chilled water coil and humidifier protection applications
Washable Electrostatic Air Filters — EC Series
For applications requiring higher particulate efficiency with MERV 6 passive electrostatic technology:
• 12x24x1 Washable Electrostatic Air Filter (ECA101224) — MERV 6 passive electrostatic filter for standard residential and commercial HVAC particulate control where higher efficiency than MERV 4 is needed
• 20x20x1 Washable Electrostatic Air Filter (ECA102020) — Popular commercial electrostatic filter for building HVAC systems requiring MERV 6 particulate capture
Media Pad Holding Frames — HPG Series
For applications where replaceable filter media pads are preferred over permanent washable filters:
• 12x24x1 Media Pad Holding Frame (HPG101224) — Galvanized steel holding frame for filter media pad replacement strategy in standard commercial HVAC applications
Frequently Asked Questions
How does the HFAS100950-1-27x35x0.875 two-stage washable MERV 4 foam air filter work?
The HFAS100950-1-27x35x0.875 uses two sequential filtration stages. Stage 1 is an aluminum mesh prefilter (expanded aluminum grid plus corrugated aluminum screen wire in a criss-cross pattern) that captures larger airborne particles—dust, lint, pollen, pet hair—before the airstream reaches stage 2. Stage 2 is 25 ppi open-cell polyurethane foam that captures smaller particles through mechanical interception and impaction. The two-stage progressive density approach extends time between wash cycles by keeping large particles out of the foam stage.
How do I clean the HFAS100950-1-27x35x0.875?
Remove the filter and rinse with a moderate-to-heavy stream of warm water from the clean side through to the dirty side until water runs completely clear. High-powered steam cleaning and chemical dips are unnecessary and not recommended. Shake off excess water and air dry before reinstalling. Do NOT apply adhesive coating after washing—this is specifically not advisable for the HF Series foam filter.
Can I apply adhesive coating to the HFAS100950-1-27x35x0.875?
No. AMFCO explicitly states that coating the HF Series filter with any adhesive is not advisable. The two-stage foam and aluminum mesh construction provides effective mechanical particulate capture without adhesive. Adhesive coating can clog the 25 ppi foam cell structure, increase static resistance, and impede subsequent washing.
Can the HFAS100950-1-27x35x0.875 be exposed to sunlight or UV light?
No. Do NOT place the HFAS100950-1-27x35x0.875 in direct sunlight or ultraviolet light. UV radiation degrades the polyurethane foam media over time, causing foam breakdown and reduced filtration performance. Store and install the filter away from UV sources including direct sunlight through windows, skylights, and outdoor UV exposure.
What is the maximum operating temperature of the HFAS100950-1-27x35x0.875?
The HFAS100950-1-27x35x0.875 HFA aluminum model is rated for continuous operation at 250°F. This is lower than the HM Series mist eliminators (HMA 275°F, HMG 325°F, HMS 900°F), which use all-metal media rather than polyurethane foam. The 250°F rating covers the requirements of most commercial and residential HVAC applications.
What are the actual dimensions of the HFAS100950-1-27x35x0.875?
The HFAS100950-1-27x35x0.875 has actual dimensions of 27.0” H × 35.0” W × 7/8″ D (±1/8” on H and W, ±1/16” on depth). The nominal size is 27x35x0.875. HF Series filters use a 1/2” undercut on height and width—actual height = nominal H minus 1/2”, actual width = nominal W minus 1/2”.
Can the HFAS100950-1-27x35x0.875 be installed vertically or horizontally?
Yes—the HFAS100950-1-27x35x0.875 may be installed either vertically or horizontally in your HVAC system without any orientation restriction. Unlike moisture separator filters (HM Series) that must be installed with the TOP label facing upward for moisture drainage, the HF Series foam air filter delivers full MERV 4 filtration performance in either mounting orientation.
What is the MERV rating and dust arrestance of the HFAS100950-1-27x35x0.875?
The HFAS100950-1-27x35x0.875 is rated MERV 4. Rated MERV 4, the HFAS100950-1-27x35x0.875 delivers 75% at rated airflow (300 fpm) dust arrestance efficiency with 24 grams per square foot dust holding capacity at rated 300 fpm airflow per the AMFCO HF Series independent test report. This efficiency level is appropriate for general residential and commercial HVAC applications, electronics cooling, machinery ventilation, and air cleaner applications requiring greater arrestance than traditional all-metal washable filters.
How often should I wash the HFAS100950-1-27x35x0.875?
Washing frequency depends on application: general residential and commercial HVAC applications typically every 1–3 months; electronics cooling with lower dust loads every 3–6 months; industrial or machinery ventilation with higher loading may require monthly washing. Visual inspection is the most reliable indicator—wash when the aluminum mesh prefilter stage appears loaded with visible dust or when system airflow noticeably decreases.
How does the HF Series foam filter compare to HM Series mist eliminators?
These are different products for different applications. The HF Series (HFA) is a MERV 4 two-stage foam and aluminum mesh and foam air filter designed for dust and particulate filtration at 300 fpm, with low air resistance suitable for electronics and HVAC air quality. The HM Series (HMA/HMG/HMS) are impingement-type moisture separators designed to capture water droplets and oil mist at 500 fpm, not primarily for dry particulate filtration. Do not substitute HM Series filters for HF Series in dust filtration applications.
Why Choose the HFAS100950-1-27x35x0.875 27x35x0.875 MERV 4 Foam Air Filter?
The HFAS100950-1-27x35x0.875 HF Series MERV 4 foam air filter provides a compelling permanent alternative to disposable panel filter programs for residential, commercial, electronics, and light industrial HVAC applications. With MERV 4 rated efficiency achieved through a two-stage progressive density media pack—aluminum mesh prefilter stage followed by 25 ppi foam stage—the HFAS100950-1-27x35x0.875 delivers effective dust and particulate capture while maintaining the low static pressure drop essential for electronics cooling, residential air handlers, and airflow-sensitive ventilation systems. Rated MERV 4, the HFAS100950-1-27x35x0.875 delivers 75% at rated airflow (300 fpm) dust arrestance efficiency with 24 grams per square foot dust holding capacity at rated 300 fpm airflow per the AMFCO HF Series independent test report.
Built with .030” thick precision-mitered aluminum framing, pop-rivet corner construction, and a two-stage media pack backed by an expanded aluminum exit support grid, the HFAS100950-1-27x35x0.875 combines structural durability with all-aluminum corrosion resistance. Actual dimensions of 27.0” H × 35.0” W × 7/8″ D install precisely in standard 27x35x0.875 nominal HVAC housings. Vertical or horizontal installation flexibility simplifies fitment in diverse housing configurations without orientation restrictions. The simple warm-water washing procedure restores full MERV 4 filtration performance throughout years of service without replacement media cost.
Choosing the HFAS100950-1-27x35x0.875 permanent washable foam air filter eliminates recurring disposable filter replacement costs while providing consistent MERV 4 particulate protection. The combination of two-stage filtration efficiency, low air resistance suitable for electronics, 250°F temperature capability, and decades of aluminum durability make the HFAS100950-1-27x35x0.875 the practical engineering choice for HVAC applications where permanent washable MERV 4 filtration in a standard 27x35x0.875 nominal footprint is the right solution. Remember: no adhesive coating (specifically not recommended for foam), no UV/sunlight exposure (degrades foam), and wash with warm water for lasting performance.
