A rattling sound from your furnace can have a couple of different causes. It could be as harmless as a loose bolt in the access hatch, which can be fixed by simply tightening the bolt. On the other hand, it could also be a sign of a crack in your heat exchanger, blower fan motor, or burner.
If that were my furnace, and I wanted to do a quick and dirty repair on it, I would find the loose joint, crumple up some aluminum foil, and stuff it firmly into the gap that is rattling, using as little material as possible to force apart the parts that are rattling. You don't want to impede air flow.
If the heat exchanger is cracked, you'll likely notice rattling sounds as the system starts up. A cracked heat exchanger can cause a carbon monoxide leak. To fix this issue, it is important to call a professional HVAC technician to come and inspect your furnace and heat exchanger.
Lubricate the Blower Motor
If it becomes dry or dirty, it can generate rattling sounds. To fix this issue, turn off the furnace, locate the blower motor, and apply a few drops of lubricating oil to the oil ports (if applicable). Refer to your furnace's manual for specific instructions on lubricating the blower motor.
There could be a few reasons why heaters make this sound, like dirty burners that need cleaning, or an excessive amount of gas inside the chambers. If you hear a banging or popping sound when the heater shuts off, it could mean your ductwork is contracting as the metal cools down.
Most frequently, the cause of a noisy radiator is air being trapped inside the system. If this is the case, it is recommended to fix this issue as soon as you can. If you find you can hear noisy pipes (especially during colder weather) this could be down to a frozen condensate pipe.
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.
If your heating system has been running well for a while but has recently developed a rattle, the first port of call is to bleed the radiators. Over time, your central heating system may induct air through the cold water feed in the loft or possibly even from a leak in the piping, pump, radiators or valves.
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.
This type of noise can also occur when you have a supply register that has come loose. In this case, tightening the register can stop this rattling sound. If you have items inside your vents, having professional duct cleaning done can solve this problem.
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.
Ask twenty professional HVAC contractors the question, “How Much Does A New Furnace Cost?” and you'll probably get the same answer... “It depends.” On average, the cost of a new furnace can range from $2,000 - $14,2001. However, factors like furnace efficiency, type, size, and much more can impact this range.
Shake, Rattle, and Roll: Causes of HVAC Rattling Sounds
Screws securing your condenser or evaporator are subject to vibration. Over time, the vibration can loosen screws, creating a rattling sound. For this problem, the solution is very simple: just tighten.
If your furnace sounds like a train grinding and scraping away on tracks, then you probably have an issue with the blower wheel. The wheel may have become unmoored and is grinding or scraping against metal it shouldn't be, or another piece has become loose or stuck in the blower.
The most common causes of a loud or noisy blower fan are worn-out bearings, an out-of-balance blower wheel, a loose motor mount, a defective capacitor, a bent blower wheel, or debris buildup on the wheel.
Clogged burners: If the rattling is coming from the burner compartment, it could be due to clogged burners. This can cause the burners to vibrate and make a rattling noise. Dirty air filter: A dirty air filter can cause the furnace to work harder than it needs to, which can lead to vibrations and rattling.
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.
Rattling (Inside the House), Clanking or Banging
Like “thwapping,” these sounds could be related to the furnace's blower assembly or motor, and are likely due to something being either loose or broken. If you hear louder banging sounds when the blower is running, shut the system off until you can get help.
This could be caused by high water pressure or, in older houses, flooded air chambers in your plumbing system. Rattling noises can also be caused by poorly secured pipes. Regardless, to prevent further damage, call a plumber to solve the issue before the damage becomes more expensive to fix.
If you're hearing a rattling sound as the pipes heat up, it's likely caused by them being loose and unsecured. 🧰 How to Fix It: To fix this problem, you'll need to simply secure any loose pipes back in their brackets.
A vibrating sound in your heating system can be caused by poorly secured pipework, trapped air, or issues with the boiler pump. Identifying and fixing the root cause will ensure the system operates smoothly.
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.
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).
If you feel like your furnace is struggling to maintain the temperature you have set on the thermostat, you're probably right–and there's likely a deeper problem at play within your heating system. Keep in mind that this isn't necessarily limited to furnaces that have totally stopped working.