7 Furnace Replacement Warning Signs

On average, a furnace will last you around 15 years, but this depends on many factors including how and who installed it to begin with, how often you have scheduled professional maintenance, and whether or not you have been replacing your filters on time.


Here are the most common furnace warning signs that your furnace has reached its limit and should be replaced:

1. AGE

According to the U.S. Department of Energy, the life expectancy of a furnace is 15-30 years. Other studies have shown the average lifespan to be more like 16-20 years.

If you have a furnace that is over 15 years old, it’s time to consider a replacement. Speak with your trusted HVAC technician to discuss options of replacement. Replacing your aging furnace with a high-efficiency unit can save you around 15-30% on your annual heating bill.

Your technician will be able to compare the efficiency levels of your current system with a new high-efficiency unit. Depending on your energy savings, you might be better off waiting a few years, but the conversation is well worth it.

Here are some common signs of an aging furnace:

Frequent Repairs
Damaged Pipes and Venting Systems


If you start noticing that your home isn’t maintaining a consistent temperature and you start to feel hot and cold flashes, it may be time for a replacement.

Other furnace replacement sigs include comfort and airflow problems. If you are having a difficult time staying comfortable, you may have a deeper problem that is affecting your safety and savings as well.

Change your air filter to see if this improves your airflow problems. If that doesn’t fix the problem, call your local HVAC technician to have a look. You may have a problem with your air ducts, ventilation, or another aspect of your HVAC system.


Take a look at your latest energy bill and compare it with years before. Is it higher than normal? Has there been a sharp spike in heating costs?

If your utility bill seems to be rising for no reason, it might be your aging furnace. Speak with your HVAC technician about the energy efficiency of your current unit. You may have originally purchased the furnace with a high AFUE (annual fuel efficiency rating) of 90% or higher, but over time this rating will go down. AFUE ratings measure the amount of fuel that is used to heat the home versus the amount that is lost through the combustion process (up the flue or elsewhere). If a gas furnace uses all of the fuel to provide heat for the home, it would have an AFUE rating of 100%.

Your HVAC technician will be able to tell you what the current AFUE rating is for your furnace. According to the U.S. Department of Energy, if your AFUE rating drops below 80%, it’s probably a wise financial and comfort decision to replace your unit with a high-efficiency one.

Older, lower-efficiency units have AFUE ratings in the 56-70% range.
Mid-efficiency heating units have AFUE ratings around 80-83%.
High-efficiency systems have AFUE ratings at 90% or above.

If your furnace is in the low-efficiency range, it’s highly recommended that you replace your furnace with a high-efficiency unit.

If your furnace isn’t that old, but you have a low AFUE rating, there is a possibility of increasing the rating with a retrofit. The only way to tell if this is a viable option for you and your heating system is to call a professional HVAC technician.


Just like a car, if you are spending more money on repairs than what you would spend on a new vehicle, it’s time for a replacement. If you have had a major repair in the last year and find yourself needing another one, it might be better to replace the entire unit.

Sometimes older units have parts that are very expensive to replace. Speak with your HVAC technician about how furnace repair costs compare with a furnace replacement.


If you see condensation near your furnace and ventilation system, this can indicate a major malfunction. If you have leaky ductwork, humidification problems, and an aging furnace, you can solve all of those problems with a professional HVAC replacement.


If you smell rotten eggs or sulfur in your home, respond immediately. Since natural gas is naturally odorless, colorless, and tasteless, manufacturers are required to add a chemical called mercaptan to give it a distinctive smell that resembles “rotten eggs.” If there is a gas leak, evacuate the home and call 911 from a safe distance.

“Rotten egg” smell can also indicate a dangerous electrical problem. When plastic components inside your outlets and switches begin to burn, they can emit a sulfur-like odor. If you suspect the smell is coming from an electrical component, turn off power to the circuit at the breaker box and call a professional electrician right away.


Pay attention to any strange sounds or smells in your home. You may have a gas leak, an improperly sized unit, malfunctioning blower fans, burner issues, or other problems.

If you hear squealing and screeching, you could have a blower motor that is in need of lubrication or repair. Loud bands and pops in your ductwork can indicate a sizing issue. Unfamiliar furnace sounds should always be addressed as soon as possible to avoid any further damage to your system.

Learn more about scary furnace sounds and what they mean here.

The best way to tell if you need a furnace replacement is to schedule an appointment with a professional HVAC technician.

Once you decide on a new heating system, you’ll want to pick the right HVAC company to perform the installation. This is even more important than choosing the replacement heating system itself. HVAC systems are often improperly installed, which can drastically reduce the effectiveness and energy efficiency of your HVAC system.

Don’t go with the lowest quote! Use this Bid Installation Checklist to vet the HVAC companies vying for the job. That will help ensure that your HVAC system is properly sized and installed.

Company: Gold Medal Service

About Gold Medal Service:

With generations of experience delivering the highest quality service available to over 100,000 customers, Gold Medal Service has become a leader in the industry with its A+ rating with the BBB. Gold Medal Service is the trusted and reliable provider for plumbing, heating, cooling, electric, and drain & sewer cleaning services in New Jersey.


Categories: Heating.