How old is my furnace?
The build date is coded into the serial number on the rating plate inside the furnace cabinet. Choose the brand on the cabinet and type the serial to get the month and year.
Find the age from the serial number
Choose the brand for its date-code chart
- Amana1 serial format
- American Standard5 serial formats
- Armstrong Air2 serial formats
- Bryant1 serial format
- Carrier1 serial format
- Coleman4 serial formats
- Comfortmaker1 serial format
- Daikin1 serial format
- Ducane2 serial formats
- Goodman1 serial format
- Heil1 serial format
- Lennox1 serial format
- Luxaire2 serial formats
- Nordyne1 serial format
- Payne1 serial format
- Rheem1 serial format
- Ruud1 serial format
- Tempstar1 serial format
- Trane5 serial formats
- York2 serial formats
Where is the serial number?
On a gas furnace the rating plate is inside the cabinet. Switch the furnace off at its service switch, lift off the upper front door and look on the inner side wall, on the top of the burner compartment or on the inside of the door.
On an electric furnace or an air handler the label is on the outside of the cabinet or just inside the front panel.
An oil furnace has two plates: one for the furnace and one on the burner, which is usually made by a different company. Use the furnace plate.
No readable serial number?
- Some rating plates print the manufacture date in plain text. When it is there, use it.
- The furnace and the air conditioner have separate serial numbers and are often different ages. Decode each one.
- A service sticker, an installation invoice or a mechanical permit gives the installation date, which is usually within a year of manufacture.
- The manufacturer or a dealer for the brand can read the date from the model and serial numbers.
What the age means
| Equipment | Typical service life |
|---|---|
| Furnace | 15 to 22 years |
What size is it?
The model number on the same rating plate gives the size: the tonnage of an air conditioner or heat pump, or the heating input of a furnace. The model number decoder reads it for 14 brands.
Questions and answers
How long does a furnace last?
Typical service life: furnace 15 to 22 years. Water quality, maintenance and how hard the equipment works move a given unit above or below the range.
Is the furnace the same age as the air conditioner?
Not necessarily. They are separate machines with separate serial numbers, and one is often replaced without the other. Decode the serial on each unit.
Do furnaces, air conditioners and heat pumps from one brand use the same serial format?
Usually, yes. Most manufacturers use one serial system across their heating and cooling equipment, so the brand page covers all of them and notes the exceptions.
Other equipment
- How old is my water heater?Tank and tankless, by serial number
- How old is my AC unit or heat pump?Central air conditioners and heat pumps
- How old is my refrigerator?Refrigerators and freezers
- How old is my appliance?Washers, dryers, dishwashers, ranges
Page last reviewed on October 5, 2026. Method and sources.