A common complaint that I get with owners of steam boiler systems is a loud banging sound at times. 

So, you are fast asleep, warm and cozy under your blankets in your bed right beside your decorative steam radiator dreaming of swimming in a pool full of hundred dollar bills when suddenly you hear gunfire and begin dodging bullets like you are Keanu Reeves in the matrix when you wake up. That was a crazy dream! Lucky you! Not so lucky for you, you then hear that same noise and realize it’s not a gunshot, and your sweet dream is now a nightmare… its your steam boiler. 

  • So, what is this loud banging noise?

When a steam boiler cools down, the steam is cooled and condensed back into water and returns back to the boiler to be reheated again and air takes the place of the steam till the boiler is called for heat once again. When the boiler heats back up and creates steam again, the steam begins to flow back up the pipes, on its way to the radiators. Now if that steam encounters any water along the way, it slams into it like a locomotive blasting through a car stuck on the tracks, BANG!!! 

  • What causes this loud banging noise?

Generally, you can contribute this noise to 2 possibilities. The first option is that the boiler could be over-filled. When this happens, there is just not enough room for the steam and it just slams the water constantly. Check your water level in the sight glass and adjust accordingly. The second, would be a low spot or “belly” in the piping somewhere. This creates a spot for water to pool up and just sit there waiting for that steam locomotive to come through and slam right into it. If this is an issue that you are dealing with, I would advise having an HVAC company out that specializes in steam boilers so that they can accurately locate the issue and remedy it for you. This could be as simple as adding a hangar to add support to the pipe in the location that it is sagging or as complex as replacing an entire section of pipe.

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