Pulsating Pipe Nightmare - Bad PRV?

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I am in need of some advice. I just bought a bank owned house "as is". It had a blown PRV that I had plumber replace before we closed (pressure was 120).
I just moved in and replaced all the toilets with high efficiency "quick fill" models.
Here is my problem:

Every time I flush the toilets (and sometimes when I run the shower) the pipes pulsate in the basement (only while filling) so its not water hammer when the valves close. I can remedy the problem by slowing the flow to the toilets at the supply valves at each of these.
*So I thought maybe the supply valve or washers were bad... replaced them.
didn't work. Next; Lowered the water pressure to the prv (55PSI). The pulsating went away :) . Fully opened all valves and no pulsation. Today it is back again.

A few notes: I have pinpointed the vibration to the PRV or Water Meter right above it. (they both shake violently). 2nd.... If my sprinklers are running this does not happen. :confused: I am going crazy.. any ideas??
Thank you!!!
 
There could be a loose washer, still, somewhere in the meter spread. It could also be debris in the PRV that needs to be cleared. Most companies will allow one free call back on the PRV to clear debris because it is known that within a week or two of installing it, there is the potential for debris to cause this problem. Not all plumbers will do this free of charge, they really aren't responsible for the stuff in your water service, but it never hurts to ask you installer.
I am concerned that you 'lowered the pressure' to the PRV to 55psi. Most domestic PRVs are preset to 50 or 55 psi and don't allow adjustment above 75 psi. Depending on the size and design of your home, you should keep it no higher than 55psi to preserve the integrity of your plumbing fixtures.
Anyways, check or have checked the valves in the meter spread, PRV cleared of debris and make sure the PRV is adjusted with a cold water valve open and then rechecked with all valves closed.
 
I agree with Caduceus. That vibration is always caused by a loose washer or something loose in the pipe. My guess is the PRV. It may be debris or a backpressure issue messing with the PRV. Does the PRV have a bypass built in? Do you have a thermal expansion tank on the water heater? Is there a pressure gauge on the house side of the PRV? Is there a strainer assembly on the PRV? Sorry for all the questions but more info is needed.
 
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check to see if the shut off is on all the way, be sure the PSI is NOT to low (below 55)and the lock nut is secure. also if you have the ball cock style in your toilets, this can also be a problem, not allowing full flow of water into fixture... GL
 
One other suggestion. Try shutting off the washing machine taps and see if the noise still exists. Most people leave them on all the time. If there is a loose washer and the taps are left permanently on , it can vibrate like you mentioned.
 
Thanks for all the suggestions everyone.. I really appreciate it. So.. I shut off the washing machine taps and the problem still exists. I do not have any ball cock type toilets... PRV does not have a bypass, strainer assembly, nor pressure gauge hookup. It is just a pretty simple one and the lock nut is secure. I checked the water pressure with a gauge hooked up to my outside hose bib(65PSI). Some other weird things happened today: Strange vibrating "sonar or UFO" sounding vibrations from the watermeter/prv while the kitchen sink running. 2nd: while my sprinklers were going.. everything was fine until zone 7 of 8 kicked in. Then the jackhammering noise came back (the original problem). I have called the watercompany to come out and look at the water meter on Friday.
 
When cleaning debris from most regulators it involves disassembling the whole thing. The strainer is inside. Not always the easiest of tasks, either.
 
Not saying this is the problem, BUT

I always check the toilets when there is a humming noise involved.

I had a 1-1/2" prv that was squealing on a multi unit bldg. PRV was less than 6 mo old so the boss had me change it out.
The new one started squealing about 2 weeks later. I told the I need to check the toilets inside each unit.
I even told the maint. crew what to look for but after 3 trips trying to get into various units I found the problem.
This video is not the actual culprit but it is the same cause. It was in the 3rd unit from the PRV.

They are not usually this loud but very common with ballcock type fill valves.

[ame="http://www.youtube.com/watch?v=eUp6uke625g"]Hummer[/ame]
 
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I wonder how many times well intended plumbers have installed water hammer arrestors when the culprit is a bargain basement ball cock.
 
Is the sprinkler system connected through a garden hose faucet or is it connected directly to the the water piping? Older frost-free hose faucets are notorious for causing vibrations due to the spring check-valve design that was popular years ago.
 
Thanks again for the help everyone:
Answer your questions. All 3 toilets have fill-valves instead of ball-cocks. (the vibrating wasn't quite as fast.. and definitely located at either the water-meter or PRV. maybe both.. they are less than a foot apart.)
My sprinklers are connected directly to the water piping through a T-joint with a ball-valve shutoff. Interestingly... if this vibrating is going on while the toilets are filling, I can continue the vibration indefinitely by turning on an adjacent faucet. Even more mindboggling: while this is going on, I can stop this vibration by fiddling with the ballvalve shutoff on the irrigation T-joint (this ballvalve was just replaced and it still happens) !!!:p This is like a computer virus!!! I have attached a picture of my meter/Prv assembly for reference. FYI bad quality picture, I only had my phone..

prvmeter.jpg
 
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Update: The watercompany came out to take a look today. Verdict: Bad PRV Shuttle Valve in my Acme EB-45. Hopefully my plumber will come out and replace it. Thanks again for everyones help..
 
Yowza, that is a hell of a Sound to be made from a Wc...

I have not yet encountered this but Will be sure to remember that video....

So, What was the solution Mr David??
 
I am at a loss. My plumber came out yesterday and replaced the PRV. The jackhammering instantly went away when flushing all the toilets. Ran the sprinklers through a cycle.. everything was fine. I thought the problem was fixed. This morning at 6am when my sprinklers were running through their 2nd cycle.. it sounded like a train coming through the station (The problem is back again). I ran down and turned off the irrigation shutoff to stop the jackhammering. So let me ask a question to everyone: What are the chances that I have 2 bad PRV's in a row.. or maybe that this brand (Acme-EB45) isn't suited for the installation. When the water company came out they suggested I get a Wilkins-70 (we have 120PSI street pressure). What are the chances this is related to a bad valve on the sprinkler system? or bad Vacuum Breaker causing this? Should I call a different plumber in at this point? This has been going on for a month now.
 
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Wow. Sorry, diydean. Maybe one way to narrow it down is to shut off the sprinkler system for a few days and see if the problem starts up when other water is used. Process of elimination is sometimes the only way to figure it out.
When you said "my sprinklers were running through their 2nd cycle" did you mean the second zone in the morning program or the 2nd cycle since the new prv was installed. I'm asking because high pressure can be created in the morning by a hot water tank heating overnight and thermal expansion builds up. It's not uncommon to have several issues being related to each other and having to pick away at them one by one.
Your first post listed a number of actions that produced the vibration sound. Have any of those come back?
You also mentioned a vacuum breaker. Do you have a vacuum breaker inline with the sprinkler system? Sometimes a vacuum breaker will make that kind of noise when water downstream becomes restricted.
You may be getting the impression that there is a lot of troubleshooting involved and it could be frustrating for you doing this via the internet and we sympathize with that.
I found a link about irrigation systems that may be useful to you. It's a bit long, but any detail can be important.
Water Hammer and Air in Pipes
 
Do you have any type of backflow preventer installed where your irrigation connects to your domestic water service?
 

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