How to Know If Your Furnace Needs Replacing

Steps

1. 1

   Find the data plate

   Open the furnace cabinet door. The data plate is a sticker or metal tag listing the manufacturer, model, AFUE, and (sometimes) install date.

2. 2

   Calculate the age

   If the plate doesn't show install date, the serial number usually encodes year of manufacture. Add 1-2 years for typical install lag. Furnaces over 15 years are in 'replacement window'.

3. 3

   Note the AFUE

   If AFUE is 80% or below, the unit is mid-efficiency — they haven't been manufactured for new residential use here in years. Operating cost is 15-20% higher than a modern 96% unit.

4. 4

   Count the repair calls

   Two or more service calls in the last 2 heating seasons = repair money is now replacement money. Add up the repair bills; if they exceed 50% of replacement cost, replace.

5. 5

   Watch the flame

   Open the burner viewing window with the unit running. Flame should be sharp and blue. Yellow or flickering = incomplete combustion, CO risk, replacement consideration.

6. 6

   Look for soot or rust

   Around the flue collar and combustion chamber. Soot = combustion problem; rust = water from a cracked heat exchanger. Both = stop running it and call us.

7. 7

   Check the rooms

   Walk every room. Are some 4-5°F colder than others? That's a duct/static-pressure problem the furnace alone won't fix — but if it's combined with an old unit, you'll address both on the replacement.