Banging pipes, even though everything is pitched properly

Gen

Our fuel company has come to our house twice in the past 2 days and still can not figure out why our pipes are making a really loud banging noise. We have a very old steam heat system with radiators. We have verified that all the radiators are pitched properly, and that the pipes in the basement are pitched properly. The heating company even replaced the pressure regulator (set it to .5 with a differential of 1) and the banging is still as bad as before. Last year we had no banging whatsoever, and this year it is extremely loud, especially for the first hour and a half that the heat is turned on.

This is a total mystery to me, and our heating company apparently! The only other suggestion I've read and not yet tried is to empty water in the boiler, because it could have accumulated gunk. I know which valve adds water, but I'm not quite sure which valve drains the water.

Any and all suggestions are appreciated!

JohnNY

My money's on...

...clogged returns.

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Gen

Can you clarify?

Hi,

I apologize for my ignorance. Can you clarify what you mean by "clogged returns" and how can I fix this?

Thanks!!

bob young

run a new return line would be your best bet

especially if existing is below grade

nicholas bonham-carter

clogged returns??

don't know whats wrong without some more information.
1. does the banging come at the beginning of the heating cycle or at the end?
2.can you feel which pipe is banging-supply or return?
3.do you have the boiler mfgs. manual?
3.can you see clean water in your sight-glass?
4.is this 1-pipe or 2-pipe steam?
5.does the boiler sometimes run short of water in mid-cycle [because of a restriction in the returns]?
the more information and observations you can gather the better.you should certainly buy one of the steam books from this site to be better able to diagnose these problems.--nbc

Gen

1. The banging typically starts about 15 minutes after we turn on the heat, and goes on for about 1 hour. The banging will then happen periodically thereafter.

2. I believe we have a 1-pipe steam system. I have isolated a few pipe sections in the basement where the exact banging seems to be coming from (although it is so loud you can hear it on the 2nd floor). I have confirmed these are pitched properly.

3. I found the manual for the boiler. Looks to be over 20 years old. It is an American Standard A-3 Oil Boiler. Anything in particular I should be looking at in it?

3. The water in the little tube next to the boiler looks generally clean (no visible dirt or gunk).

4. 1-pipe

5. We do have to manually turn to the knob to refill the water. We typically only have to do this once every 2-3 weeks. I think more often in the really cold weather.

nicholas bonham-carter

banging pipes

when the water-hammer begins, can you feel it in the pipes?when i had the same problem, i had to observe the pipes, and touch them to feel the hammering several times during several cycles.
when you checked the pitch, did you use a level? the slope is very close to horizontal, so you can be mislead by appearance alone. sometimes the pipes double back on them selves so make sure you always keep straight which it the direction of flow towards and away from the boiler
obviously you will be looking for something which has changed since the last time it operated silently. some sort of pipe restriction, which prevents the water coming back in an orderly fashion could be responsible. are any of the returns under the floor?under floor piping is a prime candidate for rotting out. would you have noticed that the boiler water is returning slowly, so that the low water cutoff interupts the firing cycle waiting for more water? although this rotting often comes with water loss, frequent topping up etc.
another thing which may have changed is the firing pattern of the burner, but i presume your oil co. tech would have checked that. suddenly increasing the flame in the boiler could cause more water to be carried up into the pipes.
another change could be pressure but without an accurate low pressure gauge rated in ounces, [gaugestore.com ] you really cannot tell if that has changes due to dirt in the pigtail.
can you observe your main air vents operating properly?
perhaps some pictures of your boiler piping would show somw installation flaw, which has now become critical.--nbc

Unknown

If you don't have them already I'd suggest you get Dan's books on steam heating.(See "A Steamy Deal" at the bottom of this page) They're well written, easy reading and will give you an understanding of just how your steam system works.
There are 3 books in the package. Start with "We got Steam Heat".

You might also post some pictures of the piping around your boiler so that it will give us a better idea of your system.

Phil_17

Hartford loop or check valve??

A couple of years ago I had a similar problem where one of my mains suddenly stopped heating. The other developed hammering and spitting vents, etc.

In our case a knucklehead had piped the boiler with a check valve where the hartford loop should have been (we have since replaced the boiler and had the piping redone as the dead men intended), and some junk had found its way into the check, holding it open. When the check is open (we didn't have an equalizer either) the pressure in the boiler was forcing water up the returns into one of my mains (the lowest one) and that was killing the performance of that main.

If you have a similar configuration, you can wind up with water in the mains and hammering like you describe.

When this happened to me I was able to open the check and pull out the junk (had to drain the boiler first), which resulted in things working as well as ever.

A properly configured equalizer with hartford loop will avoid problems like this from happening, but lot's of systems were reconfigured in the 60's and 70's with the "new and improved" check valve setup. All this stuff is covered in Dan's book TLAOSH, but sometimes it doesn't make sense until you see it for yourself

-Phil