Lennox model numbers are the most readable in the industry: the series name, efficiency and capacity are written almost in plain language. The trap is the capacity code on furnaces, which is the gas input rounded up, not the exact rating. This guide decodes Lennox furnace and air-conditioner model numbers position by position, using the key Lennox prints on its own product data sheets.
Lennox builds three tiers, and the first two letters of every model number tell you which one you have: ML = Merit, EL = Elite, SL = Dave Lennox Signature Collection.
Where to Find the Lennox Model Number
On a furnace, the rating plate is inside the front door or on the side of the cabinet, usually a foil or paper label with the model (M/N) and serial (S/N) side by side. On an outdoor AC or heat pump it is on the side of the condenser near the refrigerant line connections. Copy the model number exactly as printed, including dashes: the position of each character is what carries the meaning.
Lennox Furnace Model Number Format
A typical Lennox furnace model number looks like: ML196UH070XE36B. Use the table to split it up:
| Position | Characters | Meaning | Example |
|---|---|---|---|
| Series | ML | ML = Merit; EL = Elite; SL = Signature Collection | ML (Merit) |
| Stages | 1 | 1 = single-stage; 2 = two-stage; P or V on Signature models = modulating / variable | 1 (single-stage) |
| AFUE | 96 | Nominal AFUE: 80, 93, 95, 96, 97, 98 | 96% AFUE |
| Configuration | UH | UH = upflow / horizontal; DF = downflow | UH |
| Gas heat input | 070 | Nominal input code: 030 = 30,000; 045 = 44,000; 070 = 66,000; 090 = 88,000; 110 = 110,000; 135 = 132,000 BTU/h | 66,000 BTU/h |
| Low NOx | X | X = meets California 40 ng/J NOx standard (omitted on standard units) | X |
| Blower | E | E = high-efficiency constant-torque motor; V = variable-speed; P = PSC on older units | E |
| Add-on cooling | 36 | Nominal cooling the blower supports, thousands of BTU/h: 36 = 1.5-3 tons; 48 = 2.5-4 tons; 60 = 3-5 tons | Up to 3 tons |
| Cabinet width | B | B = 17.5 in.; C = 21 in.; D = 24.5 in. | 17.5 in. wide |
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Common Lennox Furnace Families
The first few characters identify the family, and the family tells you the tier, staging and blower before you read a single digit of capacity.
| Model prefix | Family | Stages | Blower | Efficiency |
|---|---|---|---|---|
| SLP99V / SLP98V | Signature Collection | Modulating | Variable-speed | Up to 99% AFUE |
| EL297V / EL296V | Elite | Two-stage | Variable-speed | 96-97% AFUE |
| EL296E | Elite | Single-stage | Constant-torque | 96% AFUE |
| ML196E / ML193 | Merit | Single-stage | Constant-torque / PSC | 93-96% AFUE |
| ML180 / EL280 | 80% families | Single- or two-stage | Varies | 80% AFUE |
Lennox AC and Heat Pump Model Numbers
Outdoor units use a different string. A typical Lennox air conditioner model number looks like: EL16XC1-036-230.
| Position | Characters | Meaning | Example |
|---|---|---|---|
| Series | EL | ML = Merit; EL = Elite; SL = Signature Collection; XC / XP alone on older Signature units | EL (Elite) |
| Nominal SEER | 16 | Written out: 13, 14, 16, 17, 18, 20, 21, 25 | 16 SEER |
| Refrigerant | X | X = R-410A | X |
| Unit type | C | C = air conditioner (condenser); P = heat pump | C (AC) |
| Cooling stages | 1 | 1 = single-stage; 2 = two-stage; V = variable-capacity | 1 |
| Regional standard | - | Dash = all regions; S = Southeast and North regions | All regions |
| Cooling capacity | 036 | Thousands of BTU/h; divide by 12 for tons (041 / 047 are alternate 3.5- and 4-ton sizes) | 36,000 BTU/h = 3 tons |
| Voltage | 230 | 230 = 208/230 V single-phase 60 Hz | 208/230-1 |
| Revision | A01 | Design and ratings revision (often not printed on the nameplate) | A01 |
Lennox Tonnage by Model Number
Every Lennox outdoor unit carries its cooling capacity as a two- or three-digit BTU code. Divide by 12 to get tons (1 ton = 12,000 BTU/h). Furnace numbers carry the gas input instead, so a "080" on a furnace means 80,000 BTU/h of heating, not 80,000 BTU/h of cooling.
| Model code | Size | Cooling capacity |
|---|---|---|
| 018 | 1.5 ton | 18,000 BTU/h |
| 024 | 2 ton | 24,000 BTU/h |
| 030 | 2.5 ton | 30,000 BTU/h |
| 036 | 3 ton | 36,000 BTU/h |
| 042 | 3.5 ton | 42,000 BTU/h |
| 048 | 4 ton | 48,000 BTU/h |
| 060 | 5 ton | 60,000 BTU/h |
Common Lennox outdoor families and where they sit:
| Model prefix | Family | Efficiency |
|---|---|---|
| ML14XC1 / ML17XC1 | Merit | 14-17 SEER |
| EL16XC1 / EL18XCV | Elite | 16-18 SEER |
| SL18XC1 / SL28XCV | Signature Collection | 18-28 SEER |
| ML14XP1 / EL16XP1 / SL25XPV | Heat pumps by tier | 14-25 SEER |
What the Lennox Model Number Does Not Tell You
The model number says nothing about the unit's age. That is in the serial number, and Lennox has changed its serial date format more than once. Use the Lennox serial number lookup to turn a serial into a manufacture date, or the HVAC serial number decoder hub for any other brand. The model number also does not tell you whether the unit was installed and charged correctly, which matters as much as the SEER digit for what it actually costs to run.
Decoded Your Lennox? Here Is What to Do With It
If the unit is under 10 years old and the model number shows a mid- or high-efficiency family, it is usually worth repairing. If the serial dates it past 12 to 15 years for an AC or 15 to 20 years for a furnace, the capacity and cabinet width you just decoded are exactly what you need to size a replacement. A new system at the same tonnage and input will drop straight into the same duct and gas connections.
Related: Goodman vs Lennox AC comparison · how to read any furnace data label · Goodman model number decoder.
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