Should I Repair or Replace my Gas Furnace?


Is your current furnace keeping up the indoor temperature when the outdoor temperatures are falling? Do you find yourself snuggled under blankets to keep warm in your home?  If you are not getting the results you expect from your gas furnace, you may want to have a discussion with your independent HVAC contractor on whether to repair or replace your gas furnace.

Whether your furnace is in need of repairs or you are just looking to increase the energy-efficiency of heating your home, the repair or replace decision may not be an easy one! Unless your furnace is a hazard or damaged beyond repair, there are hardly any specific rules for determining whether it’s time to repair or replace your gas furnace. However, below are a few concepts that may help.

Is Your Gas Furnace Acting its Age?

According to Energystar, your older heating system may be less efficient and have an AFUE (Annual Fuel Utilization Efficiency) rating less than 70%.1 New energy-efficient furnaces are now required to have a minimum of 80% AFUE, meaning more energy is converted into usable heat – potentially helping to lower the cost of your monthly energy bills.

As a furnace ages, it may require more than average repairs or maintenance service. The estimated cost to keep the furnace running, as provided by your local HVAC dealer, will give you more concrete reasons to replace or repair.  However, age isn’t everything.

Repair vs. Replacement Cost

Homeowners should decide a limit for the cost of repairs. How expensive does a furnace repair need to be before you decide to replace it?    At some point the cost of repairing a gas furnace could be more expensive than replacing it. A good reference point could be when the cost to repair a gas furnace is roughly 50% of the cost of a new gas furnace.  This is offered as an illustrative example. You should confirm it with your local HVAC dealer.

For example, if your furnace has a cracked heat exchanger that is not covered by a limited warranty, the equipment replacement in addition to labor costs may exceed up to the 50% threshold.  At that point, it may be time to replace. Additionally, the long-term energy bill savings of purchasing a high-efficient furnace may outweigh the price of a series of costly repairs.  On the contrary, if the problem is an inexpensive fix that restores peak efficiency, a repair may be the best approach.

To get a more specific, cost vs. benefit assessment, a homeowner should discuss repair vs. replace cost benefit with their licensed gas furnace dealer.

What’s your AFUE?

Today’s systems can have an AFUE as high as 98.5%, meaning nearly all the energy purchased is used for heating your home. An 80% AFUE gas furnace means that 80 cents of every energy dollar warms your home.1

Energy efficiency standards vary by region. To determine the minimum energy efficiency standard where you live, check with your local gas furnace dealer. 

Technology and Temperature Consistency

For some homeowners, their older gas furnace operates in either 100% ON or OFF. Historically, when the indoor temperature falls, the furnace kicks on at full capacity until the desired temperature is reached. This ON/OFF cycle means that the indoor temperatures may fluctuate as the system turns cycles. 

Advanced technology enables your gas furnace to reduce temperature swings while quietly running more efficiently. For example, a furnace with a variable speed indoor blower motor can operate at different capacities to more accurately control the heated air flow to your home. This energy-saving feature can save you money on utility bills compared to single stage furnaces because the system doesn’t have to run at full capacity to reach the set temperature. 

Duration of Home Ownership

Typically, the longer you plan to live in your house, the longer you have to recover the cost of a new gas furnace. When determining to repair or replace your current unit, homeowners should evaluate their anticipated length of home ownership by asking themselves the following questions:

  • Are you living in your forever home”?
  • How long do you expect your current home to fit your lifestyle? (getting married, having children, etc.)
  • Would a job change force you to relocate?
  • In how many years to you plan to sell your home?

While there are many of variables to examine when determining whether to repair or replace your furnace, the best source of information can come from your licensed professional HVAC contractor.  Because these local professionals can evaluate the details associated with your particular heating system, they are the most qualified to provide repair or replace guidance.  


1 Furnaces. (n.d.). Retrieved from Energy Star:
2 Should you repair or replace that product? (2014, January). Retrieved from Consumer Reports: