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  • Writer's pictureCronin Plumbing and Heating

What Makes Radiators Bang So Loudly?

If you're a homeowner, you've probably experienced a noisy radiator. If so, don't worry—it's not something to panic about. The problem is most often due to trapped air in the system that cannot get out. Here is a helpful video we've found that will help explain this phenomenon.

What exactly is a radiator?

Radiators are used in both steam and hot-water heating systems. Regardless of your heating system, the radiators that are used are basically similar and fall into two broad categories: cast iron radiators with hollow sections through which the hot water or steam flows, or tube-and-fin convector radiators consisting of copper tubes with metal fins around the outside to provide increased radiating efficiency when hot water flows through the pipes and heats them. The newer convection type or fin-type radiators are not normally used in steam systems, but cast iron radiators are used in both steam and hot-water systems.

What causes noisy radiators?

The reason for the banging is simple: there's only one pipe connected to the radiator, and steam enters through this single pipe to heat the radiator. In the process the steam condenses (it loses its heat to the metal) and forms water, which then runs back out through the same pipe and inlet valve until it finally runs all the way back to the boiler. There it is reheated and the whole process starts over again.

That is why all steam pipes must slope downward toward the boiler; if they don't, water will be trapped in the pipe and this can result in banging or hammering noises every time the steam comes up - the incoming steam tries to force its way past the trapped water and this causes the water to bang around or ''hammer'' against the walls of the pipe.

The solution...?

To cure this, radiators in a hot-water heating system have to be bled periodically - trapped air must be eliminated by opening special vents or tiny valves provided for this purpose. Call our professionals today if you suspect any issues with your heating systems - we can quickly diagnose these problems and come up with a plan to promptly fix it!

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