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Radiator Making Noise With the Heating Off? Top 6 Reasons

Radiators are excellent appliances for heating and regulating your house’s temperature. They’re built to last, but that doesn’t mean they’re without faults. If your radiator is making noises when it’s not heating the home, you might have a bigger problem on your hands.

Your radiator is making noise with the heating off because one of the following reasons:

  • Unlevel pipes
  • Metal expanding
  • Clogs in the pipes and boiler
  • Warped components
  • Radiator leaks
  • Trapped bubbles

Throughout this article, we’ll discuss what causes your radiator to make strange noises when it’s not heating and what you can do about it. Enjoy!

Pipe Leveling Issues

Radiators are aided by a series of pipes. These pipes carry water or steam to and from the boiler and radiator to generate heat. New York Times claims that if the pipes are flat or tilted in the wrong direction, the steam will have problems getting to the radiator. The resulting knock sounds are quite common in older homes with foundation problems.

How to Fix

Unfortunately, leveling the radiator’s pipes typically calls for professional assistance. The tools needed include metal saws, soldering equipment, the appropriate pipes, and potentially raising or lowering the boiler and radiator. If you think your radiator’s pipes are slightly off, the best thing you can do is look for obstacles.

Debris, loose screws, and other items can lift or move the pipes. If you can tighten the pipes, you might be able to prevent or eliminate the rattling sounds.

Radiator Metal Expansion

Radiators are made out of metal since it’s durable and heat-treated. However, extreme temperature fluctuations can cause the metal to expand and contract. According to Home Serve, you’ll hear sounds ranging from creaks and knocks to ticks and banging noises. Metal expansion can damage the radiator, so it’s important to fix it as soon as possible.

How to Fix

Much like repairing pipe issues, radiator metal expansion often calls for replacements. You can get a new radiator or locate the parts that are warped or expanded.

Every radiator has an outer layer designed to prevent burns and steam from escaping. If this layer is bent or expanded, it needs to be replaced. Contact the manufacturer for the correct part numbers. In most cases, you’ll need a professional to loosen, replace, and tighten the radiator. Metal expansion is irreversible and usually demands a new unit.

Clogged Pipes or Boilers

Clogs caused by trapped dust, calcification, mold, and other blockages can make the radiator thump and bang. The steam or water pushes through the clogs, causing the radiator to knock around from the excess pressure. The thumping sound occurs each time the pressure is released from the blockage.

How to Fix

Follow this process to remove clogs from your radiator:

  1. Turn off the power to the unit.
  2. Shut off the water supply to prevent moisture and steam from leaking.
  3. Connect the proper hose size to the radiator’s drain valve (the manufacturer should list the size in the guidelines).
  4. Open the drain valve to let water flow through the hose to drain it into buckets.
  5. Once the water is thoroughly drained, unscrew the hose, close the valve, and open the water supply to refill the radiator and boiler.

Warped Metal Fins

A radiator’s metal fins can warp from pressure buildup, excessively high or low temperatures, blunt force, and many other occurrences. If your radiator has warped, bent, or otherwise damaged fins, there’s no doubt you’ll hear strange noises. These sounds push the fins against the pipes, causing them to tick or bang around.

How to Fix

Anything that warps or expands parts of the radiator should be dealt with immediately.

Here’s a list of suggestions:

  • Bleed the radiator by opening the air bleed valve to let excess hot air escape.
  • Keep your radiator at a constant temperature when it’s freezing outside to stop excessive temperature changes.
  • Don’t place anything on, in, or around the radiator that might bump or scrape it.

If the fins are bent, the only thing you can do is hire a professional to replace them. Most home warranties are voided by DIY radiator repairs since they involve steam, gas, and foundational concerns. We recommend hiring a pro and getting a warranty for the installation or repair.

Valve Leaks

A leaky radiator will hiss or scream as the steam escapes from the hole. The higher the pressure, the louder the sound gets. There could be a leak in the fins, pipes, boiler, or anywhere else along the assembly. Locating the leak is essential if you want to prevent yourself from losing money and potentially causing permanent damage to the unit.

How to Fix

Repairing a leak can be quite simple. Try these suggestions before hiring a professional:

  • Tighten all of the couplings on the radiator, pipes, and boiler.
  • Use Rescue Tape to wrap around the pipes. It naturally bonds with the pipes, preventing leaks and pressure from escaping. One roll includes twelve feet of tape, providing more than enough for most at-home radiator leaks.
  • Ensure the air bleed valve is sealed completely. If it’s slightly open, air and steam will leak and cause hissing noises.

Trapped Air Bubbles

Is your radiator making strange gurgling sounds? There’s a good chance they’re caused by trapped air bubbles in the pipes. A Good Plumber explains these air bubbles come from pipe leveling issues, leaks, clogs, or unavoidable settling. Old pipes settle as the wood and metal around them expand, which can trap air in the system.

How to Fix

Follow this method:

  1. Locate and open the air bleed valve on top of the radiator or boiler.
  2. Once water or steam comes out of the valve, close it immediately.
  3. Let the pressure rebuild, then listen for the sounds to ensure the air bubbles are removed.

If this process doesn’t get rid of the air bubbles, there’s an air leak somewhere along the line, or the pipes aren’t leveled. Both of these scenarios prevent the steam and air from escaping when you use the bleed valve, so they need to be dealt with as quickly as possible.


  • Steve Rajeckas

    Steve Rajeckas is an HVAC hobbyist with an avid interest in learning innovative ways to keep rooms, buildings, and everything else at the optimal temperature. When he's not working on new posts for Temperature Master, he can be found reading books or exploring the outdoors.

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