Attribute Schema Library
Attribute schemaHVACR

Air Filters Attributes (HVACR Distribution)

Air filters are the highest-turn consumable in HVACR distribution: pleated panels, rigid cells, bags, HEPA, carbon, and washable metal mesh, sold to mechanical contractors, building engineers, and facility maintenance. Most orders are repeat replacements against a rack that already exists, so the data has one job — prove this filter fits and performs where the last one did.

The category resists clean data for structural reasons. Sizing is nominal: a 20x25x1 actually measures 19-1/2 x 24-1/2 x 7/8, and two suppliers cut different actuals under the same nominal. Efficiency travels on four scales at once: MERV (ASHRAE 52.2), MERV-A (Appendix J), ISO 16890 ePM classes on EU-spec jobs, and the retail-only MPR and FPR numbers customers quote back at you. Airflow and resistance mean nothing without the face velocity behind them, and suppliers rate at 300, 492, or 500 fpm without saying which.

The specs themselves live in PDF grids, one page covering 60 sizes by 3 depths by 5 MERV grades, while the item feed carries a size, a MERV number, and a price.

Core

Every SKU needs these. Without them the record is not a product, it is a row.

Filter Type
enum
Pleated Panel (also: Rigid Cell, Bag/Pocket, HEPA, Carbon, Washable Mesh)

First cut on every filter rail. Determines rack compatibility and whether the buyer is shopping a panel, a cell, or a bank.

Nominal Filter Size (W x H x D)
text · in
20x25x1

How every buyer searches and how racks are specified. Rounded up to the nearest inch by convention, not a real measurement.

Actual Filter Size (W x H x D)
text · in
19-1/2 x 24-1/2 x 7/8

The dimension that decides fit or no-fit. Industry tolerance is roughly ±1/8 in; two suppliers differ under one nominal.

MERV Rating
number
10

Per ANSI/ASHRAE 52.2. The efficiency number every spec, submittal, and reorder is written against.

Media Type
enum
Synthetic electret (100% polyolefin)

Electret media fades in service; mechanical media does not. Drives moisture tolerance and whether MERV-A matters.

Frame Material
enum
Coated beverage board with galvanized expanded metal support

Governs humidity tolerance and rack handling. Board frames sag in wet returns; metal frames go in rooftop and industrial units.

Pack Quantity (Filters per Case)
number
12

Filters ship 2, 4, 6, or 12 to a case. Without it the buyer cannot tell if the price is each or per carton.

Manufacturer Part Number
identifier
ZLP20251 (Glasfloss Z-Line, 20x25x1, MERV 10)

The reorder key. Contractors buy by MPN, not description, and the MPN usually encodes size and series.

GTIN / UPC
identifier
Each-level UPC-A plus a distinct case GTIN-14

Required for marketplace listing and GDSN sync. Each-level and case-level identifiers are different numbers.

Country of Origin
enum
United States

Drives duty, Buy American clauses on federal and school jobs, and customs paperwork on cross-border shipments.

Differentiating

What buyers actually compare on. This is where catalogs win or lose the filter.

Rated Airflow
number · CFM
1042 CFM @ 300 fpm (20x25 nominal face)

Sizing math for the air handler. Useless unless the face velocity it was measured at travels with it.

Initial Resistance
number · in. w.g.
0.21 in. w.g. @ 300 fpm

Clean-filter pressure drop. Engineers compare this directly when a MERV upgrade is on the table.

Recommended Final Resistance
number · in. w.g.
1.0 in. w.g. (1 in. pleat)

Sets the changeout trigger and the service interval. ASHRAE 52.2 loads to at least twice initial resistance.

Dust Holding Capacity
number · g
~95 g (2 in. pleat, ASHRAE 52.2 loading dust)

How standard vs high-capacity constructions actually differ. Comparative only; it does not predict field life.

Effective Media Area
number · ft²
5.16 ft² (20x25x1, 14 pleats/linear ft)

The real driver of capacity and pressure drop. Pairs with pleats per linear foot to separate standard from high-cap.

Maximum Operating Temperature
number · °F
180 °F (82 °C)

Gates rooftop, kitchen, and process air use. Board-frame pleats top out where high-temp constructions start.

Compliance & identifiers

Standards, regulatory data, and the identifiers channels reject you for missing.

UL 900 Classification
boolean
Yes — UL 900 Classified (Class 1/2 designations removed in 2010)

Named in most commercial mechanical specs and code-driven jobs. Missing it fails the submittal outright.

ISO 16890 Class
enum
ISO ePM1 50%

Required on EU and global-spec jobs; ISO 16890 replaced EN 779. Not a clean MERV conversion.

The fields that aren't in the schema at all

What most air filters catalogs are missing.

The table above is the schema most catalogs already have. These are the attributes that usually aren't in it — each one surfaced by a signal from the live market rather than by an audit of what's already there. This is what Anglera's Schema Foundry does on a real catalog, in this category.

Search signal
+ Actual Filter Size (W x H x D)

Buyers type exact dimensions like '19-1/2 x 24-1/2' or '21-1/2 x 23-5/16' into site search and get zero results. Manufacturer PDFs carry actuals; the item feed carries only nominal.

Wrong-size filter shipped against a nominal that matched. Return, restock, and a contractor who reorders from whoever lists the real dimension.

Supplier signal
+ MERV-A (ASHRAE 52.2 Appendix J)

Manufacturers publish dual values on electret lines — AAF lists PREpleat M13 as MERV 13/11A. Distributor catalogs carry a single MERV field with nowhere to put the conditioned number.

Spec engineers who require Appendix J data cannot qualify the SKU from the page and go to the manufacturer site instead. RFQ lost before quoting.

Competitor signal
+ Rated Face Velocity behind airflow and resistance

Suppliers rate at 300, 492, or 500 fpm. Catalogs publish '0.21 in. w.g.' and '1042 CFM' as bare numbers, so SKUs tested at different velocities look comparable on the same rail.

Filters compared on numbers never measured the same way. A MERV upgrade gets sold, static pressure climbs, and the coil starves.

Marketplace signal
+ Selling UOM vs Case Quantity

One pleat appears as 'Case of 12', 'Box of 6', and 'sold per filter (12/ctn)' across supplier feeds. Listings inherit whichever phrasing arrived, with no structured pack field underneath.

Customer expecting a case receives one filter, or vice versa. Marketplace suppression for pack-quantity mismatch, and price-per-filter cannot be computed.

Search signal
+ OEM Cross-Reference / Fits Model

Odd-size media filters are searched by the equipment they sit in, not by dimension — Carrier and Bryant racks take a 21-1/2 x 23-5/16 x 1. Catalogs have no field linking filter to OEM cabinet.

Replacement demand for OEM media cabinets routes to the equipment brand instead of the distributor holding equivalent stock.

How Schema Foundry finds these

Messy in, governed out.

The same value, spelled every way HVACR suppliers spell it. A filter only works once they agree.

Nominal Filter Size
20x25x120 x 25 x 120" x 25" x 1"25x20x1508 x 635 x 25 mm20X25X1 in.
20x25x1 in

Width and height get transposed between suppliers, so faceting on a raw string splits one SKU pool into several dead ends.

Efficiency Rating
MERV 13MERV-13Merv13MPR 1900FPR 10ISO ePM1 50%
MERV 13 (ASHRAE 52.2)

MPR is 3M's scale, FPR is Home Depot's. Both approximate MERV 13. Store MERV as the governed axis and keep the rest as aliases.

Frame Material
beverage boardbev boardclay-coated chipboardwet-strength boardkraft boardchipboard
Coated Beverage Board

Six spellings for one frame. Unnormalized, the frame facet fragments and buyers cannot separate board from galvanized steel.

UL Classification
UL 900 Class 1UL 900 Class 2U.L. 900UL 900 ClassifiedMeets UL 900
UL 900 Classified

UL removed the Class 1/2 split effective May 2010, but legacy supplier copy still ships Class 1 language into the feed.

What buyers ask

Every one of these should be answerable from the attributes above. If it isn't, that's a gap.

  • What does this 20x25x1 actually measure? My rack is tight.
  • Will a MERV 13 fit the same slot as the MERV 8 I'm running now?
  • How much static pressure does this add clean, and at what face velocity?
  • Is that price for one filter or for the case, and how many are in a case?
  • What's the MERV-A? My spec requires Appendix J conditioned data.
  • Is it UL 900 Classified? The mechanical spec calls it out by name.
  • Can this take 180°F on a rooftop unit, or do I need a high-temp frame?
  • Which filter fits the Carrier media cabinet — the odd 23-5/16 size?

What channels require

The same SKU, different mandatory fields per destination.

Distributor's own site and filter rail
Filter TypeNominal Filter SizeActual Filter SizeMERV RatingMedia TypePack Quantity
Amazon Business
GTIN / UPCBrandManufacturer Part NumberNominal Filter SizeMERV RatingPack Quantity
GDSN sync (1WorldSync / Syndigo) for HVACR items
GTIN / UPCBrand Owner GLNGPC Brick CodeNet ContentPack HierarchyCountry of Origin
Contractor submittal and RFQ packages
MERV Rating (ASHRAE 52.2)Initial ResistanceRated AirflowDust Holding CapacityUL 900 ClassificationFrame Material

Air Filters data, in practice

Why carry both nominal and actual filter size?

They answer different questions. Nominal is the search and spec term: racks are called out as 20x25x1 and that is what a buyer types. Actual is the fit test — the same filter measures roughly 19-1/2 x 24-1/2 x 7/8, and industry tolerance runs about ±1/8 in on width and height. Two suppliers can cut different actuals under one nominal, so a nominal match is not a fit guarantee. Odd OEM sizes make this sharper: a Carrier or Bryant media cabinet takes a 21-1/2 x 23-5/16 x 1, which has no clean nominal at all. Carry both fields, index both for search, and expose actual on the PDP.

MERV, MERV-A, ISO 16890, MPR, FPR — which belongs in the schema?

MERV under ANSI/ASHRAE 52.2 is the governed axis for North American HVACR. MERV-A is the same filter conditioned per Appendix J, which strips electrostatic charge to show the efficiency an electret filter settles into; manufacturers publish it as a dual value such as MERV 13/11A. Carry it as its own field, not a note. ISO 16890 (ePM1, ePM2.5, ePM10, Coarse) replaced EN 779 and is required on EU and global-spec work; it is not a clean MERV conversion, so store the tested class rather than a mapped one. MPR is 3M's scale and FPR is Home Depot's. Neither is a test standard. Keep them as searchable aliases only.

Why does face velocity have to travel with airflow and resistance?

Because resistance is a function of it. Suppliers rate at different velocities — the Glasfloss Z-Line pleat is rated at 300 fpm, much of the commercial pleat market at 492 or 500 fpm, and ASHRAE 52.2 permits seven test airflows from 118 to 748 fpm. A 0.21 in. w.g. initial resistance at 300 fpm and a 0.30 in. w.g. at 500 fpm are not two points on the same curve. Publishing bare numbers on a comparison rail invites an apples-to-oranges MERV upgrade that raises system static and starves the coil. Store velocity as a qualifier on both rated airflow and initial resistance.

Is UL 900 Class 1 still a valid attribute value?

No. UL revised ANSI/UL 900 in November 2009 to remove the Class 1 and Class 2 distinction, effective May 31, 2010. Filters that pass are now simply UL 900 Classified, against what were the Class 2 requirements. Legacy supplier copy still ships Class 1 language, and buyers whose specs were written before 2010 still ask for it. Normalize every variant to a single UL 900 Classified boolean and keep Class 1 and Class 2 as retired aliases so the search still lands. Do not create a class field that has not existed for over fifteen years.

More HVACR schemas

Air HandlersCondensing UnitsDuct & FittingsHeat ExchangersRefrigerant Line SetsThermostats & Controls

Run this against your own air filters.

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