Average Life Expectancies

Here are a few examples from historical data and experience:

Air conditioning compressor – hermetically sealed
12 to 15 years
Air conditioning compressor – water-cooled
20 years
Air conditioning compressor – reciprocating 20 years
Rooftop heating and air conditioning unit 20 years
Copper core boiler – heat exchanger 15 to 20 years
Steel core boiler – heat exchanger 10 to 15 years
New cast iron core boiler – heat exchanger 20 to 25 years
Old cast iron core boiler – heat exchanger 30 to 50 years
Steel tube boiler – heat exchanger 20 to 40 years
Heat exchanger – standard rooftop unit 15 to 20 years
Heat exchanger downstream of a cooling coil (package unit) 10 to 20 years
Heat exchanger – standard indoor system 20 to 25 years
Cooling tower 20 to 25 years
Central chiller 20+ years
Air handler 20 to 30 years
Gas-fired ceiling-mount unit heater 15 to 25 years
Gas-fired ceiling-mount radiant heater 20 to 25 years
Built-up asphalt and gravel roof system 20 to 25 years
Modified bitumen roof system 15 to 20 years
Inverted EPDM rubber or PVC roof system 20 to 25 years
Asphalt paving for car parking 20 years
Asphalt paving for trucks 15 years
Sealed, double glazed windows 20 to 30 years
Plywood overhead doors 15 years
Pre-finished steel overhead doors 20+ years
Electrical transformer 30 years
Electrical switchgear 20 to 40 years