Loud hammering noise where water line enters house.

[sleew]

I don't know if "hammering" is the best way to describe the sound but this is a very loud thrumming noise, kind of sounds like a loud, noisy machine running, that emanates from where the water line enters my basement and causes the pipes to shake. It happens off and on at all hours of the day but it seems to happen very frequently just after 10 P.M. Sometimes it lasts for seconds or minutes and then stops. At 10 at night it wakes me up and seems to last forever until I get up and turn on the cold water to make it stop. It usually starts up again after a few minutes and I have to go through the whole process again. At the same time I am getting sediment when I run water into the bathtub, and my water pressure went from 60 psi to above the maximum the gauge could read. That was due to sediment clogging the gaskets in my newly replaced pressure reducer. (Replaced by my plumber several weeks ago after the hammering noise had started.) I am the last house at the end of a small dead end street. There are only two houses on one side of the street and a small, 6-8 unit apartment building on the other side. My town water supervisor has not been any help in finding the problem. Any insight you have would be wonderful!

 

[Reach4]

1. Do you have a thermal expansion tank, probably near the water heater?

2. If you knock on that tank when the pressure is 60, does that tank sound empty of water? It should.

3. When you get the knocking, what does the pressure gauge read?

4. What is the maximum pressure that your pressure gauge reads to-- 100?

5. What does the city say the pressure into your pressure reducing valve is?

Since you got considerable sediment into your PRV previously, you should maybe have a sediment filter before your PRV. That filter would have to be able to accept the high pressure.

 

[Sponsor]

 

[sleew]

1. Do you have a thermal expansion tank, probably near the water heater?

2. If you knock on that tank when the pressure is 60, does that tank sound empty of water? It should.

3. When you get the knocking, what does the pressure gauge read?

4. What is the maximum pressure that your pressure gauge reads to-- 100?

5. What does the city say the pressure into your pressure reducing valve is?

Since you got considerable sediment into your PRV previously, you should maybe have a sediment filter before your PRV. That filter would have to be able to accept the high pressure.

I do have a thermal expansion tank (also newly replaced after the hammering started).
My pressure is at 52 right now and the tank sounds empty when knocked on.
The pressure stayed at 52 just now while hammering was occuring.
My pressure gauge reads to 100.
I don't know what the town pressure is but can try to find out.
I don't think there was a problem with sediment before the hammering started. The previous PRV was there since I bought the house 11 years ago and it only failed (or got clogged) after the hammering started.
Could a leak in the water main underground somewhere cause these symptoms?

 

[LLigetfa]

Under specific conditions, a PRV actively regulating can cause what you describe. It does not have to be your PRV, it could be a neighbor's PRV.

 

[sleew]

Thank you LLigetfa. Can you tell me what those conditions might be?

 

[LLigetfa]

No I cannot. Factors such as input and output pressure, volume, harmonic characteristics of the piping etc. can setup a rhythm.

 

[Reach4]

It's a mystery to me. I would suggest talking to neighbors to see if they have experienced any sounds with a time-pattern like what you have observed.