HVACDirect.com Equipment Guide

How to Read a Furnace Model Number

Your furnace model number can reveal its heating input, efficiency family, blower size, cabinet width, airflow direction, and more. Use this updated guide to identify common codes from major furnace brands before you shop for a replacement.

Find the model number
Estimate input BTU
Identify airflow capacity

Use the model number, not the serial number. The model identifies the furnace configuration. The serial number generally identifies the individual unit and production date. Never select a replacement furnace from model-number decoding alone; a licensed HVAC professional should verify the load, venting, fuel, electrical supply, cabinet fit, ductwork, and matched indoor/outdoor equipment.

First, Find the Furnace Data Plate

Turn the furnace off

Switch off power before removing an access panel. Do not open sealed burner or electrical compartments.

Look inside the front panel

The rating plate is commonly on an inside cabinet wall, the blower deck, or the back of a removable access door.

Photograph the full label

Capture the model, serial, input BTU, output BTU, fuel, AFUE, voltage, and any factory suffixes.

Codes You Will See Most Often

Manufacturers do not use one universal format, but these numeric groups appear frequently in residential furnace model numbers.

Code	Often means	Important note
`040` or `045`	About 40,000-45,000 BTU/h input	Some legacy families list output instead of input.
`060` or `070`	About 60,000-70,000 BTU/h input	Always confirm the rating plate.
`080` or `090`	About 80,000-90,000 BTU/h input	Actual published input may be slightly different.
`100`, `110`, `120`	About 100,000-120,000 BTU/h input	Input is not the same as delivered heat output.
`08`, `12`, `16`, `20`	Often 800, 1,200, 1,600, or 2,000 CFM	Roughly 2, 3, 4, or 5 tons at 400 CFM per ton.
`3`, `4`, `5`	Often nominal cooling airflow in tons	This is blower capability, not furnace heat output.
`80`, `96`, `97`	Often the AFUE product class	Verify the exact certified efficiency for the full model.

Output example: an 80,000 BTU/h input furnace rated at 96% AFUE has a nominal steady-state relationship of about 80,000 × .96 = 76,800 BTU/h. AFUE is a seasonal efficiency metric, so use the manufacturer’s rated output when available.

Shop Furnaces by Heating BTU

Select the heating input capacity and AFUE efficiency you found in your current furnace's model number to view matching furnaces.

Current furnace heating input Choose the input BTU rating identified using the model-number guide above.

Current furnace efficiency Match the AFUE percentage shown for your current furnace.

Select BTU & AFUE

Furnace Model Numbers by Brand

Most visitors using this guide will be identifying an older furnace, so each brand combines legacy examples with newer model families. Start with the example that most closely resembles the beginning of your model number. Product families change, so always verify the complete model against its rating plate or manufacturer literature.

Goodman & Amana

Older examples: GMNT0403, GUID045CA30
GMNT0403 identifies a multi-position Goodman gas furnace with 40,000 BTU/h input and 3-ton airflow. GUID045CA30 identifies an Amana upflow induced-draft furnace with a 45,000 BTU/h input class and 3-ton airflow.

Newer families: GM9C96, AM9C96

G / A - Goodman or Amana brand family
M - multi-position furnace family
9 - condensing / 90%+ class
C - two-stage family designation
96 - up to 96% AFUE product class
Full model groups such as 060, 080, 100 commonly indicate input MBH; the following digit commonly indicates nominal cooling tonnage.

Daikin

Common modern example: DM97MC0603BNAA
Daikin-branded residential furnace model numbers are newer than many of the legacy examples elsewhere in this guide.

DM97MC - modulating, variable-speed, communicating, multi-position gas furnace family
060 - 60,000 BTU/h input
3 - up to 3 tons nominal add-on cooling
B - 17.5-inch cabinet class
AA - engineering revision

Carrier, Bryant & Payne

Older example: 58WAV04515008
58WAV identifies the furnace series; 045 represents approximately 44,000 BTU/h input and 08 represents 800 CFM.

Newer Carrier families: 59MN7, 59TN7, 59TN6

59 - Carrier residential gas furnace product category
MN7 - Infinity 98 modulating family
TN7 - Infinity 97 two-stage family
A three-digit group such as 060 commonly identifies nominal input BTU/h in thousands.
Bryant and Payne use related platforms but different family prefixes; decode against the exact brand literature.

ICP Brands

Older example: N9MP2075F12A#
This pattern identifies a condensing, multi-position furnace with a 75 MBH input class and 1,200 CFM airflow.

Brands include: Heil, Tempstar, Comfortmaker, Day & Night, Arcoaire and KeepRite

Current family examples include formats such as F97CMN.
97 commonly indicates the 97% AFUE class.
M commonly identifies modulating heat; N commonly indicates natural gas.
In full models, groups such as 060, 17, and 14 commonly identify input, cabinet width, and nominal airflow class.

Lennox & Allied Air

Older example: G40UH24A045X
G indicates gas furnace, 40 identifies the Merit 80% series, UH is upflow/horizontal, 24 is 2-ton nominal cooling capacity, A is the cabinet width class, 045 is 44,000 BTU/h input, and X indicates the applicable California NOx standard.

Newer example: ML296DF070XV48BK

ML - Merit Series; other prefixes identify other product tiers
2 - two-stage heating; 96 - 96% AFUE class
DF - downflow; 070 - 66,000 BTU/h published input
V - variable-speed blower; 48 - nominal 2.5-to-4-ton cooling range; B - 17.5-inch cabinet
K - refrigerant-detection-ready designation on applicable 2025/2026-era furnace models
Armstrong Air, AirEase and Concord are Allied Air brands; their family codes differ from Lennox retail models.

Trane & American Standard

Older example: TUY080R9V3V0
This is a legacy Trane direct-vent condensing furnace pattern with an 80 MBH input class and variable-speed airflow.

Newer example family: S9V2B080U4

S - S-Series furnace platform; 9 - condensing / 90%+ class
V2 - variable-speed blower with two-stage heat
B - cabinet width class
080 - 80,000 BTU/h nominal input
U - upflow/horizontal configuration; 4 - nominal 4-ton airflow class

Rheem & Ruud

Older example: RGPJ07EAUER
This is a legacy Rheem non-condensing natural-gas furnace pattern. In this family, 07 identifies the 75,000 BTU/h input class.

Newer family example: R802V

R / U - Rheem or Ruud brand identifier in many families
80 - 80% AFUE class
2 - two-stage heat family
V - constant-CFM / variable-speed blower family designation
Full-model groups identify heating input, airflow, cabinet, voltage, orientation and factory options. New Endeavor models use longer suffixes, so retain every character.

York / Johnson Controls Brands

Older example: P4HUA12N03201
HU identifies upflow/horizontal, A is the 14.5-inch cabinet class, 12 represents 1,200 CFM, and 032 represents 32,000 BTU/h output.

Newer family examples: TM9V, TM9E, TM8E

T - residential furnace platform family
M - multi-position configuration
9 / 8 - 90%+ condensing or 80% non-condensing class
V commonly identifies variable-speed; E commonly identifies an ECM blower family.
Related brands include Coleman, Luxaire, Champion, Evcon, Guardian and Fraser-Johnston. Prefixes can vary by brand and generation.

Nortek Global HVAC Brands

Older Nordyne example: G6RA144C20C
This residential gas-furnace pattern identifies a 144,000 BTU/h input class, 2,000 CFM nominal airflow, and the C cabinet-width class.

Formerly commonly grouped as: Nordyne

Brands and labels have included Maytag, Frigidaire, Gibson, Broan, NuTone, Intertherm and Miller.
Manufactured-home furnace families can follow different formats from residential split-system furnaces.
Codes may identify fuel, upflow/downflow, condensing type, heating input, airflow and cabinet width.
Because names and product families have changed, use the exact rating plate and current Nortek literature rather than assuming an older Nordyne table applies.

Bosch

Common modern examples: BGH96M060B3B, BGH97
Bosch residential gas-furnace families are newer than many legacy models covered in this guide.

BGH - Bosch gas heating / furnace family
96 / 97 - 96% or 97% AFUE product class
060 / 080 - nominal heating input group
3 - nominal cooling airflow class in the example
BGH96 revisions now distinguish R-410A-compatible and newer R-454B safety-control generations. Verify the revision and full model before matching a coil.

Furnace Terms to Know

Input BTU/h: The fuel energy entering the furnace each hour.
Output BTU/h: The rated heat delivered after combustion losses.
AFUE: Annual Fuel Utilization Efficiency, a seasonal efficiency measure.
CFM: Cubic feet of air moved per minute by the blower.
Upflow: Return air enters low and supply air exits the top.
Downflow: Return air enters high and supply air exits the bottom.
Multi-position: Approved for more than one listed airflow orientation.
ECM / variable speed: Electronically controlled blower technology; exact capability varies by model.

Still Not Sure What Your Model Number Means?

Have the complete rating-plate photo ready and let an HVACDirect.com equipment specialist help you verify the furnace specifications.

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