Banging pipes: air or pressure regulator or ?

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I have a loud banging noise in my water pipes when the toilet is done flushing and when the spinkler system turns off. That loud banging noise is followed by what sounds like rattling pipes. I recently had some plumbing done in the kitchen: moved the hot and cold water pipes to move the sink over, ran a water line for my ice maker and water dispenser on my fridge. Also, just started up our sprinkler system for the summer. The guy at home improvement says it's the pressure regulator. I can't find one connected to the main water line, I may have to dig under my lawn to find it (if I have one). My water pressure is registering around 95 psi. Could I add a second (or first?) water pressure regulator by the main valve if I don"t find it?
I read a lot on line that the lines need to be drained.
Please help. What is going on? And how do I solve this?
Char t
 
The PRV should be on the main line inside the home before any fixture branches. If you don't have one with 95 P.S.I. you should install one. If your getting a 95# reading during the day it's probably a lot higher during times when there is less usage.

John
 
PRV's (pressure reducing valves) are not plumb under ground, they are plumb inside the house just after the service entrance valve usually. If you do not have one, you need one to reduce your pressure, 95psi is too high - should be in the range of 65-80psi. You may also need an expansion tank. Find the water service(the main water line that enters your home).Look in your basement , mechanical room to see if you have one. If you drain the lines and remove the air - Your water pressure is still too high.
 
You can also get a prv that when the pressure exceeds the set psi it releases the pressure back to the main. Eliminating the expansion tank. I dont know how others feel about this setup though.
 
I haven't tried draining the pipes yet. Should I try that first?
I don't have a basement. Could the prv be under the house? I don't see anything in the house that looks like a prv. This house was built in the 60's. It must have one somewhere, right? We've been here 9 years and never heard the banging before.
 
Its gonna be outside where the water enters the home.
 
Hi all. I have a 15 year old house with all original plumbing, heating, etc.

Several months ago I noticed a banging noise which was made randomly - perhaps i have a toilet flap that needs replacing. I did some online research and tried draining the pipes. This did not work.

I had a freelance plumber come by who looked in my utility room where the main valve and PRV are located. He didn't look at anything closely and said i need a new PRV which he would charge 350 to replace and this would solve everything. I have lost trust in this guy after a couple of incidents...

So now, my questions are do i really need a new PRV? Or should i try adjusting the PRV to reduce the water pressure?
 
Do you have a pressure gauge? If not I believe that you can get one that will attach to a hose Bibb and give you a reading. That's what I would do to check your pressure. Sounds like water hammer to me possibly. If pressure is increased (failed PRV) water hammer could worsen. When does the sound happen? It's kinda hard to diagnose unless you can re create the sound.
 
it just happens at any time throughout the day and night. the plumber asked if i had a loose flap in one of my toilets. i do have a toilet that goes "swoosh" every so often.

John, after i check the pressure and it shows it as being too high, must i replace the whole thing or can i lower the pressure?
 
Ok well in my opinion a flapper won't cause that. And try lowering it, run some water and see if the pressure remains at what you set it at. If it goes higher its seeping and you'll wanna replace it. Once you check the pressure then post back with the details
 
ok thanks. i will go to home depot tonight to buy a water pressure test gauage and see what i get.

do i just screw it on to the faucet and turn it on? i have one in my garage, also one in my back yard - they are at about the same ground level.
 
From what I've gathered yes. Never used one yet because high water pressure isn't usually an issue here. But yeah screw it on and open the valve. Should be instructions with it
 
If you are having a hammer problem with no one using water , then your toilet could very well be phantom flushing , mean the tank is loosing water then refilling. If this is the case (hammering with no one using water) the fill valve and/or the shutoff valve to the toilet could be the culprit. I only mention this because you said it happens throughout the day & night.
 
IFIXH20 said:
If you are having a hammer problem with no one using water , then your toilet could very well be phantom flushing , mean the tank is loosing water then refilling. If this is the case (hammering with no one using water) the fill valve and/or the shutoff valve to the toilet could be the culprit. I only mention this because you said it happens throughout the day & night.
Click to expand...

true...it happens whenever it wants even when no one is turning on the water. what exactly should i try? turning off the water supply to that particular toilet and see if the noise occurs?
 
stevemachine said:
From what I've gathered yes. Never used one yet because high water pressure isn't usually an issue here. But yeah screw it on and open the valve. Should be instructions with it
Click to expand...

well, i tried it. the pressure read 70 on the black needle. 120 on the red. i think 70 is the one i should read.

so this is not a water pressure issue? unless the gauge is faulty. should i try reducing the pressure reducing valve setting anyway?
 
Sorry I meant not an issue in my area which is why I haven't used that style of gauge before. Does the manual say anything about what needle means what? Maybe one of the other guys will know, but you could post a pic and it'll make it easier for us if we can see the gauge
 
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