Very, Very Old

If the unit has a GE nameplate, you don’t have to decode the serial number to get an answer: very, very old, at least 30+ years. General Electric sold their division that manufactured central heating and air conditioning equipment to Trane and ceased production in the 1980s. We have not come across a GE condenser in the last five years, but occasionally see a corroded gas or electric furnace still in chugging along—like this one we inspected yesterday.

    General Electric used several different letter and number formats over the years, but the all-numerical versions had one thing in common. A single number indicated the last digit of the year of manufacture, which forces you to guess the decade by looking at the condition of the equipment.

    The serial number format for the furnace data plate shown above uses the last three digits of the serial number for the year and week of manufacture, with the third from last being the year and final two numbers are the week. So “740” means this unit was produced in the 40th week of 1967, 1977, or 1987. We suspect it was 1977 because the home was built in 1978 and the furnace appears to be original equipment; but, either way, our all-purpose answer of “very, very old if it’s GE” still holds true.

    For the age of another brand or manufacturer, go to our blog post How do I determine the age of my air conditioner?

    To determine other key specs of your HVAC system, see one of these other blog posts: 

• How can I find out the SEER of my air conditioner?

• How can I tell whether the condenser (outdoor unit) is an air conditioner or heat pump? 

• How can I find out the size of my air conditioner? 

    To find the age of other home components, go to How can I find out the age of a roof? and How do I determine the age of an electrical panel? and How do I determine the age of my water heater? For life expectancies, visit What is the average life expectancy of the components of a house? 

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Field Guide for Home Inspectors, a quick reference for finding the age of 154 brands of HVAC systems, water heaters, and electrical panels, plus 210 code standards for site-built and manufactured homes, and the life expectancy rating of 195 home components. Available at amazon.com for $19.95.
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  To learn more about heating and air conditioning systems, see these other blog posts: 

• My air conditioner won't turn on. What's wrong? 

• Where is the air filter for my central air conditioner and furnace? I can’t find it? 

• What is wrong with an air conditioner when the air flow out of the vents is low?

• Why has the thermostat screen gone blank? 

• Why does it take so long to cool a house when an air conditioner has been off for a while? 

• Why is my air conditioner not cooling enough? 

• What are the most common problems with wall/window air conditioners?  

• Will closing doors reduce my heating and cooling costs? 

   Visit our HEATING AND AIR CONDITIONING page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.