Water hammer

[tjcsf07]

LK is this tank in a basement?

I only ask because one time when I changed a water tank in a basement I closed an old stop and drain valve to isolate the water from draining back from upstairs. After the new tank was in I had the same issues.

Cutting out the old stop and drains and replacing them stopped the water hammer issue. I guess they have some kind of rubber washer in them that comes loose when disturbed after years of not being exercised.

[LKJoel]

LK is this tank in a basement?

I only ask because one time when I changed a water tank in a basement I closed an old stop and drain valve to isolate the water from draining back from upstairs. After the new tank was in I had the same issues.

Cutting out the old stop and drains and replacing them stopped the water hammer issue. I guess they have some kind of rubber washer in them that comes loose when disturbed after years of not being exercised.

Interesting. I can't think of any valves I had operated to swap the tank that I were suspect. I just killed the main, drained the house and replaced the tank valves. But I had done that several times. Sometimes the noise does appear to be coming from the meter (installed right at the main shut off). Would have to get the city to shut the house down to replace the valve

Going to try some of these suggestions this weekend. Hopefully with some results that will steer me in the right direction.

Thanks to all for your help. Lots of good suggestions

[HotWaterHeat]

Check the system pressure. If you are getting more than 75 psi from the water meter, you need to install a PRV, just like you would do on your hydronic closed loop systems. Except this one will limit the water pressure to the house to >75 psi. rather than 12 psi for hydronic. Too much pressure causes water hammer, as do improperly secured pipe and supports. You can get a cheapo pressure gauge that hooks up to a hose bib from the big box store or Ferguson, etc. that will read to 100psi. I would start there.

[LKJoel]

Is it better to strap the pipes down nice and tight or just hold them in place?

[HotWaterHeat]

Is it better to strap the pipes down nice and tight or just hold them in place?

Well that could be a double edged sword.

Too tight, especially on hot water piping, and you could get expansion noise. But that can be eliminated if you use straps that allow for thermal expansion. I have always secured them tightly, and allowed for expansion. Talon, when used on pex generally allows for expansion. many other plastic hangers (we are talking residential here, where it commercial, there I use cushion clamps on strut channels) are also suitable. Those copper and steel two hole clamps, when over tightened, tend to bind when too tight, causing noise during thermal expansion.

[pacnw]

to >75 psi.

not harping because I do not use this often enough to remember, but does this mean less than or greater than 75psi?

I thought you read the open part, mouth, as it appears. >=greater than and <=less than.

[pacnw]

You might be surprised to find a PRV on the main line already and it is the cause of the problem, as was stated.

I had one that had similar diagnosis and I did find a failing/stuttering PRV on the main. had customer contact utility and not heard back.

[Peztoy]

Just something to check.
I replaced my hot water tank. Same for same. But I moved it 3 ft closer to the outside basement wall. I then had water hammer after that. I have a 100 ft garden hose outside. I discovered that if I leave the outside faucet for the hose on I get water hammer. Turn off the faucet, noise goes away. I don't know what the science is, but that fixed it.

[LKJoel]

You might be surprised to find a PRV on the main line already and it is the cause of the problem, as was stated.

I had one that had similar diagnosis and I did find a failing/stuttering PRV on the main. had customer contact utility and not heard back.

It wouldn't be built into the meter would it?

[LKJoel]

Just something to check.
I replaced my hot water tank. Same for same. But I moved it 3 ft closer to the outside basement wall. I then had water hammer after that. I have a 100 ft garden hose outside. I discovered that if I leave the outside faucet for the hose on I get water hammer. Turn off the faucet, noise goes away. I don't know what the science is, but that fixed it.

So the full hose is acting like a cushion tank. Interesting

Are long straight runs worse for hammer? The hot and cold mains are 3/4 copper and run the length of the house (the hot starts about half way down, cold goes all the way front to back almost 50')

[ch4man]

not harping because I do not use this often enough to remember, but does this mean less than or greater than 75psi?

I thought you read the open part, mouth, as it appears. >=greater than and <=less than.

i > u. i greater than you

http://despair.com/superioritee.html

[pacnw]

It wouldn't be built into the meter would it?

that I have ZERO knowledge of.

The one I had was very similar to the type use in hydronic systems and was after the meter( both inside the home).

[LKJoel]

that I have ZERO knowledge of.

The one I had was very similar to the type use in hydronic systems and was after the meter( both inside the home).

I'll have to take a closer look