Anyone have any experience with "water hammer"?

We have an oil heat forced hot water heating system. And once it kicks in the pipes bang.

Sometimes it's a lot and last a few minutes, other times it's just once or twice.

Super annoying and will wake us up out of a deep sleep at night, plus I don't want to cause any damage, been reading a lot about it.

Thanks.

http://www.doityourself.com/forum/boilers-home-heating-steam-hot-water-systems/513379-my-expansion-tank-bad.html
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Your forced hot water loop is basically a close system you will have an auto feed that's located on the cold water feed at the boiler.this will keep the pressure range from 12-15 psi.

The noise you are hearing is the expansion of the pipes when they are heating up and rubbing on the wood or the hangers.

Water hammer is usually on the cold water line public water pressure will normally range from 55-90 psi anything higher you'll need a pressure reducing valve that would get installed just after the water meter.
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Air in the lines, needs bleeding

http://www.thisoldhouse.com/toh/video/0,,20353316,00.html

Radiators or baseboard?
https://www.youtube.com/watch?v=r1ecdBTzbRE
http://www.thisoldhouse.com/toh/video/0,,20503995,00.html

A really loud bang? I say it's this

Air in the lines, needs bleeding

Ross, we have both, most rooms have radiators but a couple have baseboard
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Three videos there covering what to look for in different systems. Eliminate the expansion/rubbing possibilities and move on from there. I think one of the videos covers one way system steam, but not bleeding

I was thinking expansion tank and or air vent, air purger...hmm
http://www.stevejenkins.com/blog/2013/12/testing-and-replacing-a-hot-water-expansion-tank/Posted from my iPhone/Mobile device