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How Old is Your Furnace? Here’s How to Tell

A furnace should last between 15 and 20 years. If you don’t know your HVAC system’s age, you might be in for an unpleasant surprise when the heating goes out this winter.

Newer units likely have a date of manufacture stamped somewhere on the furnace. Older systems, however, require a little detective work. Here’s how to determine your furnace’s age.

Find the Serial Number

The serial number should be on a rating plate inside the service panel door on the furnace cabinet’s front. Not there? Check the is blower deck: it’s the small horizontal surface right above the blower component.

Here’s what to do if the label still alludes you: Turn off the furnace's power by either flipping off the unit’s switch or cutting its power at the circuit breaker. DO NOT SKIP THIS STEP because you’ll need to inspect the fan blades. Some older models have the serial number stamped on the fan.

Decode the Serial Number

If you know how to read it, the serial number can tell you when the unit rolled off the factory floor. Often, the first four digits of the serial number signify the date of manufacture. Let’s say the serial number reads 1013CA5465. In this case, 1013 can be interpreted to mean the unit was manufactured on the 10th week of 2013. That would mean this seven-year-old furnace has at least 13 years ahead of it with routine maintenance.

You can also get a close approximation of the furnace’s age by looking at its service record. Gas furnaces often have a sheet affixed to the unit where a technician can note the service date. This might also contain the date the unit was installed.

Consult a Pro

If the serial number is indecipherable, you may need to consult an expert. An HVAC technician might be able to give you the exact date the furnace was made. At the very least, they can thoroughly assess your heating system to give you a good idea of its condition and remaining useful life. To schedule an appointment with AAA Service Plumbing, Heating & Electric call (303) 622-3449.