You are most likely hearing a delayed ignition. When too much gas builds up in the combustion chamber and the ignition is delayed, your furnace experiences a small gas explosion. This can be caused by low gas pressure, clogged burners, and dirty equipment.
Loud Bangs, Rumbles, Knocks, or Booms
Loud noises like this are a sign of a build of gas in a furnace. The noise you hear can mean your heat exchanger is at risk of cracking. Even worse, it's a sign that something dangerous could happen if you continue to use your heater.
Thumps and bumping noises, like an unbalanced washing machine, often indicate an unbalanced blower wheel or motor. This is a serious issue that requires immediate HVAC repair. The blower wheel and motor are major furnace parts and you don't want them bouncing around.
There are a few different answers to the question about why a furnace sounds like it's backfiring, though. The most common answer is that the age of your furnace may mean that worn down parts are causing gas to backup in a way that eventually leads to a sudden release and boom.
If your furnace makes a booming sound when it starts up, this is usually due to what HVAC specialists call “delayed ignition”. Unfortunately, delayed ignition should never be ignored as it can cause severe damage to your furnace and even your family if left unaddressed.
A puff back in a furnace is a volatile explosion that occurs inside your furnace. The result of this explosion is fire and smoke being spewed out from your furnace.
First, know if you have a gas, electric or oil furnace. Electric furnace installation tends to be the least expensive, ranging between $3,000 and $7,000, according to HomeAdvisor. Installing a natural gas furnace falls in the range of $3,800 to $10,000, and an oil furnace ranges $6,750 to $10,0000.
If your furnace suddenly produces loud, sudden banging or booms, you should call an experienced technician as soon as possible. These sounds could indicate stuck ignition, a potentially dangerous situation involving carbon monoxide which is deadly.
Replacing a furnace blower motor costs $560, on average. Depending on the size and type of motor, most people pay $300 to $900. The average blower motor replacement cost is $560, but the final price depends on labor fees, as well as the cost of the parts.
We're here for the long run. So if you hear a squeal, a new click, grinding, or popping when your furnace is at any point in the heating cycle, it's best to have a tech take a look and catch things early.
Popping. If you hear popping sounds and you don't have a bag of popcorn in the microwave, you could be dealing with dirty furnace burners or damaged air ducts. When the burners are dirty, the buildup prevents them from igniting, which causes too much gas to build up, making a popping sound.
If your furnace is making an obnoxious noise, it's likely because the furnace blower motor is turning on and off as part of normal heating furnace cycles. Make sure your thermostat is set properly to the desired temperature and off when you don't need heat (like overnight).
Although it is possible for a gas furnace to either catch fire or explode, it's highly unlikely. If there is a danger of this happening, the furnace will usually simply shut off—as it's designed to. Regular maintenance will further reduce this already unlikely event.
Strange Noises
Many healthy furnaces will maintain a consistent whirring sound, which is handy in letting you know that it's in good working order. If you begin to hear strange noises—banging, rattling, irregular hums, groans, rattles, etc. —then that could mean that there's something wrong with the furnace.
If your furnace isn't working, it's an emergency. Especially during winter. Just because it isn't working doesn't mean that there still aren't things at play within the system that could cause further harm. Get it addressed as quickly as possible so these things aren't allowed to develop into further problems.
If your furnace produces a loud humming or buzzing sound, there could be an issue with the motor. There may also be something wrong with the fan. It can be something as simple as a loose screw, loose door, or improperly installed furnace filter.
Over time, normal wear and tear can cause the furnace motor to start squealing, grinding, buzzing, or whistling sound. Here are some of the most common culprits behind furnace motor noise: Bearings wear out – Bearings allow the blower wheel to spin smoothly.
Instead, you should take immediate action and contact an HVAC professional. A cracked heat exchanger can produce different sounds, including popping, banging, whistling, or scraping.
The Average Furnace Lifespan
A well-maintained furnace can last at least 15 to 20 years, but completing annual maintenance and being diligent with repairs can extend its life even longer.
Your base homeowners policy will cover many types of damage to your furnace. An extra endorsement known as Equipment Breakdown Coverage (EBC) will give you additional coverage for certain types of mechanical or electrical failure.
You'll be looking at a different cost depending on the location of the furnace, the size of your home, and the type of furnace. But the average cost per unit can range anywhere from $2,672 - $6,575. The national average is $4,820 - $9,350 for a full furnace installation.
A furnace explosion is usually the result of ignition and instantaneous combustion of highly flammable gas, vapor, or dust that has accumulated in a boiler. The effect of the force from the explosion is often much greater than the boiler combustion chamber can withstand.
Delayed ignition is when that gas isn't ignited immediately, allowing the gas to build up in the furnace. The gas keeps building until—BOOM—it reaches a flame and finally ignites, causing a small explosion in your furnace.
As reported by the National Fire Protection Association (NFPA), heating systems like furnaces are a leading cause of home fires, causing almost 50,000 blazes, 500 civilian deaths and more than $1 billion in significant property damage every year.