With proper care, a gas furnace can sometimes last for 20 or even 30 years. Still, HVAC professionals recommend replacing furnaces once they reach 15 years or sooner, in some cases. As a furnace ages, efficiency drops, heating costs rise, and it becomes harder to keep the house warm. It can also fail without warning, leaving you without heat in the middle of winter.
Why Furnace Efficiency and Performance Decline With Age
The extreme heat inside a furnace puts major strain on certain components and leads to them continually experiencing increased wear and tear. One of the main reasons why efficiency and performance decline over time is that the strain causes the blower to no longer work as effectively.
The blower is responsible for drawing air into the furnace through the return air ductwork and circulating the heated air around the house through the supply ducts. Once it begins wearing out, it has more issues with circulating sufficient air. The result of this is that the furnace can’t heat the house as quickly or effectively, leading to it staying on for longer and using more energy. If the blower isn’t circulating enough air, it can also lead to some rooms never getting fully warm. This is especially common for rooms that are further away from the furnace and toward the end of the supply ducts.
Older furnaces tend to have more issues with incomplete combustion. Burners can become dirty, misaligned, or restricted, which disrupts the air-to-fuel mix and leads to incomplete combustion (soot, cooler flames, CO risk). When natural gas fully combusts, it burns cleanly and produces an extreme amount of heat. Incomplete combustion results in the flames not giving off nearly as much heat, which results in the air the furnace puts out not being as hot. Incomplete combustion is also a major safety hazard, as it can lead to carbon monoxide being produced. This is why every home with fuel-burning appliances should have working CO detectors on each level.
Yet another concern with incomplete combustion is that it can lead to soot buildup inside the furnace’s heat exchanger. Soot can interfere with the heat exchanger’s ability to absorb heat and transfer the heat to the air flowing through the furnace, further decreasing the unit’s performance.
Older furnaces often run 70%–80% AFUE. Modern condensing models reach 95%–98% AFUE, so more heat reaches your rooms per dollar. If you have an old conventional furnace with a pilot light, replacing it with a new condensing furnace could save you several hundred dollars a year. If you opt for a two-stage furnace or a modulating furnace, your savings can be even higher.
Signs You Should Replace Your Old Furnace
Having a certified HVAC technician inspect and service your furnace yearly can sometimes allow you to get more than 15 years of life out of it without a significant drop in efficiency or performance. However, you still run the risk of your equipment needing a major, costly repair. When it comes to repairing an old furnace, HVAC technicians usually recommend adhering to the rule of 5,000. This rule simply states that if the age of the furnace multiplied by the estimated cost of repairing it is equal to or higher than 5,000, a furnace replacement is a better option.
Another time when it’s not worth repairing your furnace is if you keep needing to have various issues repaired. You can usually expect a heating system will need a few repairs over its lifetime. If you’re frequently needing to have different components replaced, it’s a good indication that your HVAC equipment is wearing out and will just need to be repaired more often.
Your gas bills can obviously fluctuate from month to month and year to year due to changes in your rates. How long your furnace runs also affects usage. If you notice that your gas usage keeps increasing and that your heating system runs longer regardless of how cold it is, it’s another sign that your furnace can no longer perform effectively. This doesn’t necessarily mean it’s going to suddenly die, but it does mean you’ll have to deal with increasingly high energy bills until you finally decide to replace it.
Contact the Trusted Experts
Since 1950, Waterbury Heating & Cooling, Inc. has been a trusted source for furnace installation, repair and maintenance in Sioux Falls, SD. We’re a Lennox Premier Dealer and offer a wide selection of efficient furnaces to meet your needs. We offer financing for new furnace installations on approved credit, and our team is available 24/7 to handle any emergencies.
To schedule a furnace inspection or a replacement consultation, contact Waterbury Heating & Cooling, Inc. today.
