CPVC pipes violently vibrating

[tucsonhouse]

Recently bought a home in AZ and had the PRV, irrigation line backflow preventer and a leaky hose bib replaced. A water softener was removed and the piping re-routed back into the system. And a thermal expansion tank was installed at the water heater.
The pipes in the home are CPVC and the temperature is currently near 35F low and 65F high. But the ticking noise is consistent no matter the time of day or night. The pipes are not strapped down.

When the hot water at the faucets are turned on, I get a slow tapping that ramps up to a rapid, machine gun ticking in the ceiling and walls in the room close to the water heater. The ticking is not as consistent near the rooms farthest away from the water heater but it does happen. The ticking does slow down and does, for the most part disappear after a few minutes.

The pressure at the hose bib near the PRV is consistently near 60psi with a random max of 80psi when left for 48 hours or more.

A plumber cut a hole is in the ceiling of the room at the noisiest point. My plumber says that he can feel the pipes vibrate when the hot water is turned on. He tried to cushion the pipe but the noise persists.

The previous owners said they never had any pipe noise issues.
The problem started in Nov and after an uncapped y-pipe was sealed off on the sewer line. And has gotten worse with colder weather and with the PRV and other replacements and attempted fixes. It started with a slow tick. Then rapid ticking. Then multiple ticking locations. And now with some light water hammering.

Can there be another reason for the ticking besides CPVC expansion?
If it is CPVC expansion and contraction, wouldn't this be a well-known and well-documented issue?
Wouldn't the expansion tank stop any water hammering?

Strapping down the pipes may stop the noise but concerned the noise may just move further down the line and am very concerned that the contraction/expansion will cause pipes to break in future and would prefer to find the source of the issue, if there is one.

Any help is greatly appreciated.
Had three plumbers over. They have been in AZ for years, know the climate, worked with CPVC and have not come experienced an issue this rapid and loud.

 

[frodo]

pipes are going to jump when you turn the water on, just the way it is.

physics thing, above my pay grade.

you mentioned you installed a prv for the whole house. what is the pressure on both sides of the prv?

 

[ExtraMilePlumbing]

an expansion tank is not meant for stoping vibrations in the pipe . I would first start off by draining the whole house to return air to the water hammer arestors if there's even any

 

[tucsonhouse]

Thank you for your replies.

The pressure on the "house" side of the PRV is just below 60psi.
I do not know the pressure on the "city" side of the PRV. I am not able to install the pressure gauge to measure that.
I hope I understood that correctly.

The expansion tank was installed to address the water hammering noises and as a preventive measure due to the max pressure of 80psi being measured by the pressure gauge.
No water hammer arresters installed. My understanding is that the expansion tank and the arrestor both address water hammering and pressure fluctuations.

So, can there be another reason for the ticking besides CPVC expansion? Could it be the water heater in some way? Something stuck in the CPVC piping?
And if it is CPVC expansion and contraction, wouldn't this be a well-known and well-documented issue?
The ticking and pipe vibrating is my main concern.
The water hammering is secondary and something I thought the expansion tank would address. But maybe not...

 

[tucsonhouse]

pipes are going to jump when you turn the water on, just the way it is.

physics thing, above my pay grade.

you mentioned you installed a prv for the whole house. what is the pressure on both sides of the prv?

Thank you for your repy.

The pressure on the "house" side of the PRV is just below 60psi.
I do not know the pressure on the "city" side of the PRV. I am not able to install the pressure gauge to measure that.
I hope I understood that correctly.

 

[frodo]

if your pipes are not tied down. or are loosely strapped. that is the noise.

also, ticking, can be, not saying it is. a pebble, or a piece of solder in the pipe rolling around

that said. a water heater makes noise, they tick, gurgle, rumble,

just the way it is, it IS a tank full of hot water that is moving.

my advice. insulate your piping, and strap it down

turn the pressure down at the prv, try 50 psi, see if it helps

 

[KULTULZ]

1) PVC/CPVC piping not properly secured in runs is going to move with varying water pressure.

2) The piping does expand/contract with differences in water temp.

3) A Thermal Expansion Tank is designed to absorb WH thermal expansion.

4) The PRV purpose is to limit supply pressure.

5) To control water hammer, water hammer arrestors are used.

6) Your WH nipples may be heat traps, and they can cause/transmit noise(s).

- CLICK HERE - Thermal Expansion & Contraction Explained - CLICK HERE-

 

[frodo]

what type of main water valve do you have before the water softner ?

I am thinking it is not a ball valve but a globe valve with a faulty washer, or, installed backwards

 

[tucsonhouse]

if your pipes are not tied down. or are loosely strapped. that is the noise.

also, ticking, can be, not saying it is. a pebble, or a piece of solder in the pipe rolling around

that said. a water heater makes noise, they tick, gurgle, rumble,

just the way it is, it IS a tank full of hot water that is moving.

my advice. insulate your piping, and strap it down

turn the pressure down at the prv, try 50 psi, see if it helps

Thank you again for your response.

The more I read all the responses, the more resigned I am to believe that the pipe vibrations are due solely to thermal expansion and unstrapped CPVC piping tapping against wood framing causing the ticking noise.
My only concern about insulating and strapping the piping is if that would restrict the pipe expansion and somehow increase the likelyhood of a break in the line.

 

[tucsonhouse]

what type of main water valve do you have before the water softner ?

I am thinking it is not a ball valve but a globe valve with a faulty washer, or, installed backwards

The main water shutoff valve is a ball valve. I assume you are talking about that one since that is the only valve I know of that is between the PRV/city line and where the water softener was (before it was removed).

The order as I understand it is city line, PRV, T line to irrigation backflow preventer, shutoff valve, where the water softener use to be, then the water heater and the cold water line.

 

[tucsonhouse]

1) PVC/CPVC piping not properly secured in runs is going to move with varying water pressure.

2) The piping does expand/contract with differences in water temp.

3) A Thermal Expansion Tank is designed to absorb WH thermal expansion.

4) The PRV purpose is to limit supply pressure.

5) To control water hammer, water hammer arrestors are used.

6) Your WH nipples may be heat traps, and they can cause/transmit noise(s).

- CLICK HERE - Thermal Expansion & Contraction Explained - CLICK HERE-

This information was very helpful. Thank you.

I will definitely look into the link more carefully as it will take some time to decipher some of the math.

The expansion/contraction of the CPVC pipes seems likely to be the main cause of the vibrating pipes but I just don't understand why this is not as well documented of an issue if this is a common problem... at least here in AZ.

Do you have an opinion on a hot water recirculating system such as this one Watts-500800-Recirculating-System-Built-In?
Will it decrease the CPVC life expectancy if the CPVC is constantly hot? (Can't be worse than the expansion contraction of the CPVC, I would guess.)
How about PEX piping? Is this type of piping more accepting of temp variations?

Insulating the pipes and strapping them down may stop most of the noise but I worry about the extreme vibrating of the pipes from expansion/contraction. I can't imagine the CPVC is made for such extreme variations in temp to make them expand so much to make them vibrate violently.

I am also concerned that re-piping the house with PEX may not solve the pipe expansion/contraction issues.

 

[KULTULZ]

(IMO)- (See Disclaimer Below)

Unless there is something in the install we don't see or realize yet, secure the piping where it vibrates badly (maybe use clamps that allow the tubing to slightly slide) and see what the results are.

In the referring URL I gave, there are formulas/charts that show the expansion/contraction rate of the piping within a continuous straight run and if you have to make allowances.

If only one (or more) faucets cause the vibration(s), maybe a shock absorber install at that fixture?

Keep us posted as this is a learning thread...