Resonance (jack hammering) at main shutoff when toilet tank starts filling

[rest_in_pasta]

Observed the phenomenon after new HE washing machine was installed in 2018. Had no instances of jack hammering at the main water shutoff valve with previous washing machine.

-House built in 1988
-all polybutylene piping was replaced in the mid-90s with 1/2" copper
-water shut off (in the house) is a CPVC ball valve (replaced in 2008; original valve was a gate valve)
-replaced water heater in 2019 and no thermal expansion tank was installed
-Sioux Chief water hammer arresters at the washing machine inlet and Wal-rich high capacity rubber inlet hoses
-recently replaced toilet fill valve and supply stop (Korky 528X and Dahl 1/4-turn copper compression) in the master bath

The resonance/"jack hammering" only occurs when after flushing the toilet in the master bath (when the tank is filling). "Jack hammering" goes away when turning on any bathtub faucet and turning it off. Can hear the water flow "pulsing" (turbulence) at the shutoff when any faucet is turned on.

 

[Terry]

Often I will get hammering from a part way opened shutoff on a toilet if the rubber seal is loose. I open them all the way and then back it in just a little. Normally to align the handle up and down.
Sometimes the fix is to replace the shutoff. I like the 1/4 turn shutoffs, not so much the multi-turn.

 

[Sponsor]

 

[rest_in_pasta]

Often I will get hammering from a part way opened shutoff on a toilet if the rubber seal is loose. I open them all the way and then back it in just a little.

Exactly what I did after installing the new Dahl 1/4-turn supply stop and performing the first flush. Fully opened the supply stop > flushed the toilet > water hammer started > slightly turned the supply stop lever clockwise > water hammer stopped

It's odd that the water hammer/"pipe knocking noise" only occurs when flushing the toilet in the master bath.

 

[Terry]

Exactly what I did after installing the new Dahl 1/4-turn supply stop and performing the first flush. Fully opened the supply stop > flushed the toilet > water hammer started > slightly turned the supply stop lever clockwise > water hammer stopped

It's odd that the water hammer/"pipe knocking noise" only occurs when flushing the toilet in the master bath.

What fill valve do you have in the tank? I would think about changing that too.

 

[rest_in_pasta]

What fill valve do you have in the tank? I would think about changing that too.

Korky 528X (recently installed) for master bath toilet.

 

[rest_in_pasta]

According to Fluidmaster, I am hearing a resonance or "jack hammering" whenever the toilet in the master bath starts filling. A new Korky 528X fill valve replaced a >10-year old defective Fluidmaster 400A fill valve. A new Dahl 1/4-turn supply valve replaced a >10-year old defective Keeney 1/4-turn valve.

The toilet in the hallway bath has a Korky 528 that was installed six years ago and no resonance issues (still has the 32-year old Brasscraft multi-turn supply valve and toilet supply hose is not too old).

Recently, a Toto Eco UltraMax was installed in the powder room. No resonance was observed (installed a new Brasscraft 1/4-turn valve- KTC19 series and not the crappy G2 series valves from the Homer Depot).

Any suggestions?

 

[rest_in_pasta]

Follow up:

The pressure reducing valve was the culprit. Pressure readings at the hose hibs were at ~90 psi and the needle on pressure gauge was bouncing a bit. 30 year-old Watts PRV was removed.

Hopefully the new Cash Acme EB45 w/ SharkBite fittings will hold the water pressure steady @ ~59 psi for the next two decades.

No more jack hammering/water hammering from the toilet in the master bath so far.