How old is my Lennox furnace?

1. Find the rating label: Behind the upper front service panel, on the left inside wall of the cabinet or on top of the blower deck; the spot varies with efficiency (80% or 90%) and with how the furnace is installed.
2. Take a photo of the whole label, or note the model and serial numbers.
3. Check it on Appliance Age. It is free, and no account is needed.

Behind the upper front service panel, on the left inside wall of the cabinet or on top of the blower deck; the spot varies with efficiency (80% or 90%) and with how the furnace is installed.

Keep the model, serial and any separate production code or printed date together. Not every serial number contains a publicly decodable date.

Lennox serial number: look beyond the plant code

Lennox HVAC equipment using plant/year/month serials · Sources checked October 12, 2026

In the documented Lennox numbering system, the opening characters identify the manufacturing plant. The next two digits indicate the year, followed by a month character. The first two digits therefore should not be read as the manufacture year.

Keep the full model number, including its suffix. Lennox uses model and serial information together to identify equipment and replacement parts.

This illustration applies to the documented style, not every Lennox product or era. Do not use the date on a replacement component to date the whole system.

• Lennox model and serial nomenclature: serial-numbering diagram

Use the format that belongs to this product family. A printed production date, a supported serial code or manufacturer confirmation can establish the age. Repeating year codes may leave more than one possible year; a model-series introduction date helps narrow the range but does not date your individual unit.

Furnaces typically last 15 to 25 years. Use, water quality and maintenance matter more than the brand. Change the filter every one to three months and have it serviced yearly.

77 Lennox models are currently ENERGY STAR certified, 62 of them sold in Canada. The certified models went on the market between 2025 and 2026. An older Lennox furnace may use more energy than today's certified models.

Source: ENERGY STAR open data, 2026-10-08.

Parts that wear out most often on furnaces:

• Air filter
• Hot surface igniter
• Flame sensor
• Inducer motor
• Pressure switch
• Blower capacitor

Have the model number from the rating label ready so the parts fit.

Every Lennox check is compared with Health Canada, U.S. CPSC and U.S. NHTSA recall notices.

Questions

How do I find out how old my Lennox furnace is?

Find the rating label (Behind the upper front service panel, on the left inside wall of the cabinet or on top of the blower deck; the spot varies with efficiency (80% or 90%) and with how the furnace is installed), then enter the serial number or a photo of the label on Appliance Age. It checks supported serial date codes or a printed date for you, free; some formats need more information.

Where is the serial number on a Lennox furnace?

Behind the upper front service panel, on the left inside wall of the cabinet or on top of the blower deck; the spot varies with efficiency (80% or 90%) and with how the furnace is installed.

Can I tell how old my Lennox furnace is by the model number?

The model number tells you which model it is, not when your unit was made. Look for a manufacture date or a supported date code in the serial number, printed next to the model number on the same label.

Can I decode a Lennox serial number myself?

Some Lennox product families have serial date codes, while others need a printed date or manufacturer confirmation. Repeated year codes can produce multiple candidate years; the model and original documents help resolve them.

How long does a Lennox furnace last?

Furnaces typically last 15 to 25 years with normal use and maintenance.

Where can I get Lennox furnace parts?

From an appliance parts retailer. Have the model number from the rating label ready so the parts fit.

Other Lennox appliances

• Lennox water heater (tank)
• Lennox boiler
• Lennox air conditioner
• Lennox heat pump