Steam pipes generating banging noise

Old 01-18-10, 05:33 PM
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Exclamation Steam pipes generating banging noise

I have a steam heating system, and we just had a brand new boiler installed not too long ago. Right after it was installed, the pipes began generating a very loud banging noise (water hammer), so we called the contractor who installed the boiler, and he "flushed out the system," which made the very loud banging go away. However, although the pipes do not bang as loudly as they used to, it is still noticeable. Lately what I have discovered is that the pattern of banging is completely random. There is no telling when the pipes will make noise. Sometimes when the heat turns on one of the pipes leading to a radiator in the living room will make on large "bang!" and then be silent for the rest of the heating cycle, and sometimes when the heat turns on that same pipe won't make any noise. As I said earlier, it's completely random. Every single day I wake up at around 5:30 in the morning when the heat goes on, and cannot fall back asleep until school starts at 7. So if I go to bed at 11, then instead of sleeping 8 hours like I should, I only sleep 6 1/2 If I weren't so sensitive to noises while asleep then it wouldn't be a problem in the first place. A contractor said he can redo the pipework so that the pipes are pitched properly for $1800, but my dad doesn't want to pay such a large sum of money. Any suggestions as to what I should do?
Old 01-18-10, 06:13 PM
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Hello, and welcome to DIY...

The main reason steam will cause banging is from dirt, or steam and water mixing. Believe it or not, they don't like each other. You mentioned that the system is fairly new. By flushing the system, does that mean he just drained it down a few times, because that will not work. I installed one last winter for a customer and everything was pre-cut so I assumed I did not introduce any foreign materials into the heating system. I was very wrong. What MUST be done at the completion of a steam boiler is what is called Skimming and should be done with a special chemical made for this purpose as well as done at high temps ( just as the water begins to turn to steam). This "skimming" is done by pouring the special chemical into the boiler and bringing the water in the boiler up to steam temp, then opening a port someplace above the water line and SKIMMING the oils and dirt off the top until it is clean. I have seen this take several attempts before the system is finally clean. A sure sign of contaminated water is if the water level in the glass keeps rising and falling a lot. This is known as "Surging".
There are other things to look for such as improper piping, causing "wet steam" or piping and/or radiators not pitched correctly, causing the water and steam to mix. This will always cause a banging noise.
I would start with proper skimming of the boiler and checking the pipes and radiators for improper pitch. Improper piping will take more time to explain.

Steam is a great way to heat but if not done properly it can be a horror show.

good luck.

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