Water hammer

Brad White_9

You probably should post this as a New Topic to recieve your own replies and so this does not get lost. As posted, this is piggy-backing on another thread regarding a steam system.

But a short answer is, it sounds like thermal expansion. Try outdoor reset if available so that you greatly lessen cycles and rate of expansion, not to mention save money!

Cheers,

Brad

Joe_86

Pipe Banging

I've read the FAQ's but I'm not quite sure their answers could solve my problem. I had serious bangng from pipes near the boiler, but since turning down the pressure, it has subsided considerably. But now I am experiencing banging in one of the radiadors on the first floor. All my rad's are pitched correctly. When my boiler was installed near the end of last season, I guess I never mentioned to the plumber that several rad's in the house are disconnected. Could it be that or do I just need to adjust that rad somehow?

Unknown

Joe,

One pipe system or 2 pipe?

arthur_3

noisey pipes ?

hi, we have a tap,tap,tap, noise i cant locate where its coming from every morning when central heating comes on all we can hear is tap,tap,tap!!!! its driving me mad, we have normal combi boiler a sime i think. please help british gas havent a clue? regards arthur.its more prevalent in the bedroom.

Unknown

arther,

Not much info to go by. Is the system hot water or steam? are the rads fin-tube or cast-iron? If you can better describe your system details to us, we can better help you. OK?

Dave Stockhoff

Similar problem

Brad, I have a problem similar to Arthur's. Can you explain "outdoor reset"?

I have a 2-pipe steam system. I have thermal expansion noise in 1 rad. It's loudest when the unit is warm and the system is heating up (but also cooling).

The unit sections heat in the order A, E, B/D, C, if A is the section on the inflow end and E on the outflow end. I suspect either water or sediment is semi-blocking steam from the center sections. I'm going to replace the vent just for kicks---it never hisses.

Anyway, whatever helps Arthur might help me.

thanks!



I just realized "outdoor reset" might be a thing rather than a process, so I googled it and see it is indeed something you can add to your system.

I'm guessing it would not help me, since steam is always the same temperature. I don't see how it would help Arthur either, but what do I know . . . .

Steamhead (in transit)

Dave, most 2-pipe steam systems

should not have air vents on the radiators. The exception is if it dates back to about 1902 or earlier. This was the 2-pipe, air-vent system and each rad had shutoffs on both supply and return.

If you're not sure what you have, take pics of several rads and post them here.

Outdoor reset on steam generally varies the quantity of steam produced, rather than its temperature. There have been systems that controlled the steam pressure or vacuum by outdoor temperature, but these were mostly used in commercial or public buildings.

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Brad White_149

Outdoor Reset

At the risk of hijacking this thread, outdoor reset as I am using it, applies to hot water. It is a control strategy (as a verb, "to do outdoor reset") and the controls to make it happen (as a noun).

Essentially, the water supplied to the radiators varies from near room temperature when the outdoor temperature indicates heat in any form is required. This water temperature increases to what the design maximum when the outside temperature is at the coldest design minuimum.

The changes occur very gradually as does the temperature change outdoors (one hopes!). With constant circulation, you will see temperature changes of a degree to a few degress per hour.

Compare this to an on-off system where the water supplied runs from room temperature to limit (68 to 180) within ten minutes. Heck of a way to run a plant, but all too common. Imagine the stresses imposed in such a short amount of time.

Dave Stockhoff

Ah, I see. Yep, that sounds like something for a hot-water system.