A low hum is normal while the furnace runs, but if the noise is loud during a cycle or comes on when it wasn't present before, there could be an issue with the fan or capacitor.
It's normal if it's the gas jets. Go down to your furnace and open the access panel, then turn the heat up and see if the sound comes from the jets.
The most important noise that you may want to hear is the whoosh of warm air flowing from your heater and into your home. Aside from this, there are some other sounds that may be normal to hear, such as a brief amount of clicking at the start of the heating cycle or a small amount of crackling after the cycle ends.
Secondly, you may hear a hissing noise. This would happen in the event of a cracked fitting or connection. If outside, it may be a cut or broken line (Note: A gas meter does make a noise when it is operating. This is normal.).
Normally that only occurs when gas is being fed to a furnace or pilot light, but it also sounds when gas is escaping from a joint, seam, or hole. If you suspect a leak, either from a gas alarm, foul smell, or loud hissing, shut off your gas main line and consult a professional for repair.
It's often said that you shouldn't be able to hear a central heating system that's running well and efficiently. Your heating should come on and off seamlessly with little to no noise.
Normal Furnace Noises
Sometimes there is a little bit of a pop or click as the furnace fires up, then the heating system settles into a dull hum as it runs. Think of it like the click you hear when you turn on the burner on a gas stove.
On a normal day, your home's furnace might make a little noise as it starts up, when it's turning on, and then when it turns off. You can always expect to hear some noise from the furnace. The thing about this noise is that it should never be disruptive.
However, most gas furnaces typically last between 15 to 20 years before efficiency declines and repair costs increase, so it's wise to consider replacement around the 15-year mark to ensure optimal performance and safety.
If your furnace turns on but no heat is produced, there may be a problem with the fuel supply or the ignition system. If something is stopping your furnace from receiving gas, there is no fuel to combust so the furnace will not create any heat. The furnace turns on but no heat comes out.
If you've lived with a gas furnace at any time in your life—and most people have—you'll know what sounds to expect from it: the whoosh of the burners igniting, the clicking of the ignition as it comes on, the whir of the blower fan, the movement of air through the vents, and an occasional rattle as the metal vents ...
Unusual sounds from your gas heater can indicate underlying issues. Whistling or Hissing: Clogged or dirty air filters may cause whistling or hissing sounds. Popping or Banging: Delayed ignition can lead to popping or banging noises and requires prompt attention.
It's normal to hear a noise as your furnace starts, especially in old furnaces. This noise could be a product of your furnace igniting and working correctly. An initial pop or click as your furnace turns on is entirely normal, as your furnace should then settle into a dull thrum as it kicks into gear.
Popping or banging: These noises are often caused by the expansion and contraction of metal components as the heater heats up or cools down. While some level of this noise is normal, excessive or sudden popping and banging could signal an issue.
Bump the temperature up 3-4 degrees above the room temperature so the heat will come on. Watch the thermostat for a minute or two and make sure “aux” or “emergency” heat doesn't come on yet. Check outside and make sure the condenser unit started up successfully and you don't hear any unusual noises.
There are a variety of problems that can cause your furnace to produce loud noises. Types of noises such as scraping, banging, whistling, and popping may be a sign of a loose part, cracked heat exchanger, or dirty gas burners.
Any odd noise coming from a furnace, boiler, or heat pump could mean something in the system has malfunctioned and is in need of repair. While low humming sound is typical when heating systems operate, any sound that is not common coming from the furnace or heat pump could mean a problem is present.
2) Turn on your boiler/programmer and central heating, making sure your hot water is turned off. 3) Turn up your room thermostat or boiler thermostat, and make sure the boiler fires up. 4) Wait for 5-10 minutes, and feel the top and bottom of you radiators in each room, make sure they warm up evenly.
If there are cracks in the exchanger, it can make a rattling noise when it first turns on. Your heat exchanger is constructed of metal, so the noise you're hearing is the sound of the crack in the exchanger expanding as it begins to heat up. One of the main reasons for a cracked heat exchanger is a lack of airflow.
Key points about carbon monoxide poisoning
Most CO exposures happen in the winter. A common source is unvented space heaters. Symptoms of CO poisoning include headache, dizziness, weakness, nausea and vomiting, rapid heartbeat, shortness of breath, seizures, chest pain, disorientation, and loss of consciousness.
Here's what you should DO if you smell gas: DO leave the home, building, or area of the suspected leak. Get to a safe area as quickly as possible. After leaving your home, DO call the 24-hour emergency number for Peoples at 1-800-400-4271, or call your local emergency response number.