Stumped re water hammer issue

[Jeff H Young]

70 psi alone would not be the cause of a hammer but IMO could be a factor if there is a problem might make it worse.
I just have a preferance for it lower If you told me it was 70 and everything was fine (no Hammer) I wouldnt have a problem with it but personaly I would need some reason to set a regulater that high.
The pressure in all the plumbing fixtures is the same so now the story is you have 75 psi at laundry. Dont know at what point anyone else would say lets try turning pressure down a bit but Im there already
Im not that big on installing arrestors but ill do what ever it takes to fix it and that includes adjusting pressure putting on aresstors , changing fill valves on toilets and sometimes tearing into walls. I try the easier and cheaper things first. also I keep an open mind to trying things that might not be very convincing but sometimes worth a try. Mostly these have been warranty calls as most people will put up with a little noise rather than pay us to rip walls apart and hourly rate to chase this down is not something people will pay .

 

[Stumped789]

Your advice on pressure makes sense to me. There is probably another issue driving the water hammer, but if reducing the pressure could alleviate the issue and doesn't sacrifice performance, why not. We will try that before calling out another plumber. Thank you.

Any thoughts on the hard water possibly being the culprit? If so, what would be some ways to address that? We've already installed a softening system, but as far as previous damage, is there anything we can do?

 

[Sponsor]

 

[Jadnashua]

RIgid pipes tend to use 90-degree fittings. Just like your car doesn't like to do a tight turn, water doesn't either. That's one advantage of using pex, at least if you don't try to treat it like copper and just use a fitting at the beginning and end of the run...it bends around corners quite well. Otherwise, especially when you try to stop the flow with a quick acting valve, it will try to move the pipe when it hits either the end (at the valve) or at any right-angles. Clamps can help, but when they are too tight, you'll often end up with clicking noises when they expand/contract with thermal changes, most common on hot lines.

 

[Jeff H Young]

Stumped 789 you havent givin much helpful info. what kind of pipe in main part of house , how old is that pipe. when exactly did the hammer start. what pipe is in the addition? long runs? any idea what size any of the pipe is? btw I dont suspect water softener is related. does hammer on hot? and cold? Undersized pipe or old galvinized pipe that has started rusting on inside leading to fresh pipes of copper or pex combination can create a water hammer but you wont provide us any clues. Also try to figure out where the noise is coming from

 

[Stumped789]

I wanted to come back with an update and more questions.

I had the water heater company come out to review the installation and talk about possibly adding an expansion tank. They checked the pressure at the water heater and this time it was high (over 100). So on the water heater company's suggestion, I had a plumber come out and replace the regulator. Of course, the hammer issue persists.

So, now I'm wondering if the high pressure at the water heater had nothing to do with the regulator? Maybe I do need an expansion tank? Could the lack of an expansion tank be the source of the hammer issue? We never had an expansion tank with the old water heater.

To answer the questions above by Jeff:
The pipes that are making the noise are probably around 15 years old. The hammering started a few months ago, possibly around the time I replaced the water heater, although this could have been coincidental. Pipes are copper. There are some long runs. I don't know the size of the pipes. The water hammer seems to be only on the hot side. The hammering sound seems to be from the pipes in the attic space, which are within a couple of feet of the water heater in the garage, but pretty far away from the upstairs fixtures which are triggering the hammering when they are turned off.

Thank you very much for your input!

 

[Jeff H Young]

I wanted to come back with an update and more questions.

I had the water heater company come out to review the installation and talk about possibly adding an expansion tank. They checked the pressure at the water heater and this time it was high (over 100). So on the water heater company's suggestion, I had a plumber come out and replace the regulator. Of course, the hammer issue persists.

So, now I'm wondering if the high pressure at the water heater had nothing to do with the regulator? Maybe I do need an expansion tank? Could the lack of an expansion tank be the source of the hammer issue? We never had an expansion tank with the old water heater.

To answer the questions above by Jeff:
The pipes that are making the noise are probably around 15 years old. The hammering started a few months ago, possibly around the time I replaced the water heater, although this could have been coincidental. Pipes are copper. There are some long runs. I don't know the size of the pipes. The water hammer seems to be only on the hot side. The hammering sound seems to be from the pipes in the attic space, which are within a couple of feet of the water heater in the garage, but pretty far away from the upstairs fixtures which are triggering the hammering when they are turned off.

Thank you very much for your input!

Good Info!
Expansion tank could possibly help but Ive never tried one to solve hammer or heard of anyone doing it, but the effect of one I belive could only help and not cause a hammer.
I would get it attic if possible in area of noise have a helper attemp to create noise. and properly strap loose pipes. I have spent many hours tring to solve water hammer issues not always easy
since you have a prv on your house and pressure is known to be exsessive you should install an expansion tank THIS HAS NOTHING TO DO WITH YOUR WATER HAMMER ISSUE .

 

[Reach4]

The hammering sound seems to be from the pipes in the attic space, which are within a couple of feet of the water heater in the garage, but pretty far away from the upstairs fixtures which are triggering the hammering when they are turned off.

Just to confirm, you get a single bang when you turn off certain fixtures, or when they turn off automatically, such as the fill valve on a toilet shuts off. When you turn off a faucet fast, you get a bigger bang than if you turn it off slower.

What is your water pressure after the PRV now?

 

[Stumped789]

Just to confirm, you get a single bang when you turn off certain fixtures, or when they turn off automatically, such as the fill valve on a toilet shuts off. When you turn off a faucet fast, you get a bigger bang than if you turn it off slower.

What is your water pressure after the PRV now?

It is a thud/rattle type sound when the kids turn off the shower or sink faucets upstairs quickly. The toilet upstairs does not seem to cause any issue.

The plumber set the pressure at 70 after the new PRV.

 

[Jeff H Young]

Why in heck 70psi? your not getting it just pay and have it fixed.

 

[Stumped789]

Why in heck 70psi? your not getting it just pay and have it fixed.

I'm not really sure why this is the second plumber who has wanted to keep the pressure at 70. We may turn it down ourselves.

 

[Jeff H Young]

I'm not really sure why this is the second plumber who has wanted to keep the pressure at 70. We may turn it down ourselves.

Hey sorry but Id try down to 50 to see what happens you gotta try some differant things and more pressure not going to help

 

[Reach4]

I'm not really sure why this is the second plumber who has wanted to keep the pressure at 70. We may turn it down ourselves.

Dribble water as you adjust while watching a pressure gauge.

 

[Stumped789]

Dribble water as you adjust while watching a pressure gauge.

We will adjust it tonight.

Does it matter where we dribble water from?

We also have appointment for expansion tank to be installed in the morning. I will update. Thank you for all of the help.

 

[Reach4]

Does it matter where we dribble water from?

Not as long as it is after the PRV. Some have their outdoor hose bibs supplied before the PRV, so that is why I hedged.

You might adjust down to 35 initially. If that quiets the pipe, and you want more pressure, you could try higher.

 

[Stumped789]

Update: We turned the pressure down to 50 and installed an expansion tank. The pipes are much quieter and a shower leak that I had (which I was waiting to repair) is now gone. Thank you for the advice to turn down the pressure.

I'm still hearing a slight rattle in the attic when the kids turn off the shower hard upstairs. We will go up to the attic this weekend to see if we can duplicate the rattle and locate the source. If you have any advance input on that process, please let me know. You have been most helpful about the water pressure. I'm disappointed our plumbers didn't focus on that earlier on.

 

[Reach4]

Did you try 35 psi?

If you keep 35, drop the air precharge in the thermal expansion tank to 35. Air precharge is always set with water pressure zero.

 

[Stumped789]

I can't do anything under 40 because my reverse osmosis system requires a minimum of 40.

 

[Reach4]

I can't do anything under 40 because my reverse osmosis system requires a minimum of 40.

Ah, yes. RO units work better at higher input pressures. That was the motivation for the initial PRV setting I suspect.

They make electric booster pumps for RO units.

Would it be practical run a separate pipe from before the PRV to the RO? Maybe a separate PRV would be needed, and maybe your RO can accept the whole high pressure.

Shower valves by nature tend to be slow closing. Could it be the kids get a kick out the the bang?

 

[Stumped789]

Hmm that's interesting that you said shower valves are slow closing. One of our plumbers also mentioned that. So it is not a likely place for a water hammer.

My kids are not little. Actually the heavy handed one is 19 and they actually can't hear the rattle by the shower. I can only hear it downstairs because the rattle comes from above in the attic. So they are definitely not doing it on purpose. I suspect they are not even turning it off that hard.

I don't think I want to put too much work into the house by running a new pipe, as we are not looking to stay here beyond a couple more years. Just looking to fix things so we don't have a disaster before we sell the house. Thank you again for your help.

 

[Jadnashua]

There are some shower valves that say to install hammer arrestors when installing them, but they are not all that common.

Water has mass, just like a car and you strapped into it. None of them like to hit a brick wall, which is what a valve emulates. The higher your pressure, the faster the water will be going, so the effect is worse. Force=1/2 mass * velocity squared...so a little faster makes a much bigger difference than you might otherwise think.

An expansion tank is required when you have a closed system. Now, your WH T&P valve may not open without one, but that also means that water IS leaking somewhere in the house to relieve the pressure caused by the water expanding. I do not know why people resist putting one in. In the town where I live, it's been mandatory for nearly 30-years, even if you don't have an PRV, as they have been installing check valves in the water meters as they've been updating them. This is often true for anywhere in the USA you might live. If you have a tight system with no leaks, without an ET in a closed system, you WILL cause the T&P valve to open and drain some water off. This is not a good practice. Some people put in a pressure release valve (same idea as part of the T&P valve, but why dump water each time the WH runs unless maybe you use it to prime a floor trap.