Deciding whether to repair or replace your furnace can be tough. Replacements are expensive, but repairing a failing system may cost you more in the long run. In order to ensure you don’t wind up throwing good money after bad, you’ll need to know the difference between a furnace that’s merely broken and one that’s circling the drain.

Signs Your Furnace Needs to Be Repaired

Like any other machine, furnaces require regular maintenance. While no one likes their heating disrupted, especially in winter, most of the problems you’ll encounter can be fixed without too much trouble, such as:

  1. No Heat. The problem is likely a faulty thermostat. Most of the time, it simply needs new batteries. Or it’s clogged with dust. If neither of those work, try resetting the breaker. If that doesn’t work, then your furnace’s starter might need to be replaced.
  2. Not Enough Heat. Clogged filters prevent warm air from circulating. Pull them out and shine a light through them. If you can’t see anything on the other side, it’s time for some new ones.
  3. Dust. Depending on their thickness, filters have to be replaced every 3-12 months. If you’re replacing them more often than recommended, you’ve got a dust buildup inside your furnace. Your local HVAC person can clear it out.
  4. Noise. A lot of noise from your furnace is actually due to poor ducts. Adding some insulation might solve the problem. Or it might be time to oil the gears. Sometimes, adjusting the pilot light will fix things.
  5. Rapid Cycling. When a furnace rapidly cycles on and off, the culprit might be clogged filters or a dirty flame sensor. Bad filters cause the furnace to overheat while a blocked flame sensor tricks your furnace into thinking the pilot’s gone out. 
  6. Yellow Flames. Furnace flames should be blue. If they aren’t, it means your burners need to be cleaned or the furnace isn’t producing the right mix of gas and oxygen. Either way, call a professional and have them take a look.
  7. Gas Leak. Anytime you smell gas coming from your furnace, leave and get a service technician right away. The problem is serious but fixable.

Signs Your Furnace Needs to Be Replaced

With proper maintenance, your furnace can last decades. But eventually, there comes a time when repairs are no longer worth it and the unit has to be replaced. You’ll know you’ve reached this point when:

  1. Maintenance Becomes More Frequent. If you’re calling for repairs more than once or twice a year, and the cost of repairs is steadily going up, odds are you need a new unit.
  2. Your Furnace is More Than 15 Years Old. A furnace can last for up to 30 years, but if it’s older than 15 and you’re starting to see problems, replacing it is generally more cost-effective.
  3. The Repair Cost is Over Half the Replacement Cost. If it’s going to cost thousands of dollars to fix your furnace, you’re better off buying a new one. 
  4. Your Heating Bills Are Going Up. Rising heating costs mean your furnace is struggling to produce enough heat. Replace it before it wears out entirely.
  5. It Can’t Heat Your House Evenly. If half your house is warm and the other half is cold, your furnace is not working efficiently anymore. Old parts can’t be fixed; they have to be replaced. 
  6. The Furnace Makes Noise When You Turn It On. When the furnace starts to hum, rattle, pop, or screech after you activate it, its components have begun to deteriorate. Sometimes they can be repaired or re-aligned, but if your furnace is old, replacement may be the only option.
  7. It Emits Carbon Monoxide. No matter how old it is, any furnace that produces carbon monoxide is unsafe and needs to be replaced as soon as possible.