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JackP
Plumbing mystery

I hope someone can offer some advice on a problem that has perplexed me for some time. I have knocking water pipes. I'm familiar with water hammer and its causes, none of which apply in my case. Furthermore, the pipes aren't loose. The knocking seems to occur close to where the water line enters the house (basement). Now the mystery is this: it happens almost exclusively in the early morning hours, say from 4-6 a.m. I can turn on any faucet for a few seconds and it stops. Any suggestions would be much appreciated.

JLMCDANIEL
Re: Plumbing mystery

I wonder if it could be water hammer on the main line. 4 to 6 is about the time everyone gets up to start getting read for work and school.
Jack

JackP
Re: Plumbing mystery

The knocking begins before anyone gets up. In fact, the noise often wakes us up. Any running of water stops the noise and we rarely hear it during the day or evening.

Gray Watson
Re: Plumbing mystery

Water pressure at the main at those times might be elevated. Possibly expansion from the water heater?

JLMCDANIEL
Re: Plumbing mystery
JackP wrote:

The knocking begins before anyone gets up. In fact, the noise often wakes us up. Any running of water stops the noise and we rarely hear it during the day or evening.

It may be before you get up, but not necessarily before your neighbors get up or factory and business starts. Water hammer can also occur in a municipal water system especially after the storage towers have been replenished at night and there is more pressure. Opening faucet would have the same effect as a water hammer arrestor.
Jack

JackP
Re: Plumbing mystery

Thanks for the responses. I have a pressure regulator in the main line in the area where I hear the noise. I wonder if the regulator could be the source of the problem? The house is forty years old and most of the plumbing is original.

misfitter
Re: Plumbing mystery

so what i would do to answer this question/problem is to install a water hammer on the main line. I know a prv (pressure reducing valve) might equalized any flucuation in the city water pressure. the water hammer install should take less than 1hour and less than $50 for someone with plumbing skills. the prv is way more expensive and time consuming.

Gray Watson
Re: Plumbing mystery

Check out that pressure regulator. It might need service or adjustment if that checks out then check out your water heating system.

Gray Watson
Re: Plumbing mystery

You might want to check with the city works department ask if they did any repair or maintenance in your area around the time this problem developed could have stirred up and shot a load of sediment and scale through your system restricting screens as in your prv and such or causing your water heater to run longer. You have a closed system so if you are building pressure during a long period of non use that would be first concern.

One more thing. Check with the other members of the family, see if someone is flushing the toilet and returning to bed a few minutes before this knocking starts.

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