Furnace System GuideA failing furnace often gives warning before it quits, and a few signs point to a safety problem rather than a comfort one. The statements below come from dated ENERGY STAR and EPA sources. Anything that could not be verified against a live source is left out.
Rising Bills and Weak Performance
When a furnace starts to fail, it often works harder to deliver the same heat. ENERGY STAR notes that a dirty air filter causes the system to work harder to distribute air, which can increase energy costs. A furnace that runs longer and costs more may be struggling.
ENERGY STAR also states that airflow problems can reduce a system's efficiency by up to 15 percent. Uneven heat or a system that cannot keep up can trace back to airflow trouble.
Start by checking the simple causes. If a fresh filter and a clear return do not fix weak performance, the equipment itself may be wearing out.
Dirt and Neglect Lead to Failure
ENERGY STAR states that dirt and neglect are the top causes of heating and cooling system failure and inefficiency. A furnace that has gone years without service is more likely to break down.
ENERGY STAR also warns that a dirty air filter can damage the equipment, leading to early failure. Repeated short cycling, overheating, and strain shorten a furnace's life.
If your furnace has a history of skipped maintenance, treat new noises, weak heat, or frequent cycling as signals to have it inspected before the season peaks.
Electrical and Combustion Warning Signs
Some failure signs are safety issues. ENERGY STAR warns that faulty electrical connections can cause unsafe operation of the system and reduce the life of major components. Burning smells or tripped breakers are worth immediate attention.
ENERGY STAR also states that improper gas or oil connections are a fire hazard and can contribute to health problems. Problems with the burner, gas pressure, or heat exchanger are on the safety side of the ledger.
These are not do-it-yourself items. If you suspect an electrical or combustion fault, shut the unit down and call a licensed professional.
Carbon Monoxide: The Sign You Cannot Ignore
A failing furnace can become a carbon monoxide source. The EPA lists leaking chimneys and furnaces, and back-drafting from furnaces, gas water heaters, wood stoves, and fireplaces among the sources of carbon monoxide in the home.
The EPA describes symptoms that rise with exposure, including headaches, dizziness, confusion, nausea, and flu-like symptoms that clear up after leaving the home. At very high concentrations, carbon monoxide can be fatal.
If you have any carbon monoxide concern or notice these symptoms, leave the area and call for help. The EPA recommends keeping gas appliances properly adjusted and having a trained professional inspect, clean, and tune up the central heating system annually.