Clunk Sound From Grohe Grotherm Triple Function Shower Valve

[PGB1]

Hello All!
I installed Grohe Grotherm Triple Function Thermostatic shower valve (Part 29142000). The water is turned on & off with push buttons.
There is a "Clunk" when any of the three buttons are pushed to turn off the water. The "clunk" is louder the higher the outlet's flow. If the supply to the valve is off, there is no clunk. (Plumbing is all Type M copper tubing 1/2", pressure is 48 psi-g)

I tried installing size AA water hammer arresters on the supply lines at 5-1/2" from the valve. The "clunk" sound didn't change. I verified that there is no movement from hammer in any pipe or the valve body with dial indicators.

Grohe telephone support first told me no water hammer arresters were needed. Next phone tech said they are yes needed. Next tech said to clean the cratridges because of lime build up. (I skipped this as the valve is brand new.) To me, the phone people are "winging it". (None asked the model of the valve.)

My guess is that this might be normal since it is push button, but that is only a guess based on the "Tried everything else" method.

Do any of you have experience with Grohe push-button type valves? Do they make noise?

Thanks For Helping me solve this mystery!
Paul

 

[Tuttles Revenge]

What you are describing sounds like a classic Water Hammer. The water has momentum as its flowing through the valve and out of the shower fixtures. Then when you push a button, the water movement stops and that momentum carries through the piping to the walls and makes noise. The cure for this is water hammer arrestors at the source of the quick closing valve.. ie the grohtherm. Or as close to it as possible with degrading results the further away it is from the valve.

 

[Sponsor]

 

[Reach4]

If you turn off one stop (hot or cold) and adjust the temperature to hottest or lowest, as appropriate, does the bang differ much? I am wondering if one of the arrestors is defective.

 

[Jeff H Young]

possibly nothing wrong with the valve or the hammer arrestors . just gotta work through the possibilitys is the shower head installede or just an open pipe right now? you left the flow restrictor in the head (that actually helps reduce hammer )

 

[PGB1]

Thank You all for taking time to reply.

I did try different water hammer arresters, thinking one might be bad. No change in sound.
Using only hot or cold, the sound is the same. (I can only test it quickly on Hot because the thermostatic shuts the flow off.)
The shower head is installed with flow restrictor (2.5 gpm), but the tub is an open pipe with a boiler drain temporarily on it, as is the side shower fitting.

Since the valve has 3 buttons, I can test each one item-by-item or all open at once. The clunk is different on each. Shower head is the quietest. The side shower and tub pipe are loudest. Turning the water flow way down, instead of pushing to turn off, on each will also cause the clunk. I even turned off the supplies, removed pressure and tried again with water on. Same clunk.

I 'm pretty convinced water hammer is solved because I got a little over-kill on and put dial indicators on the inlet pipes to look for movement. They're on the valve housing and the pipes to each item. None showed movement. Removing the water hammer arresters and capping the tees gave movement in the supply pipes, indicating hammer. Putting the arresters back in showed no movement in the pipes.

Is it at all possible that this sound is normal due to springs or something in the push button valves? (No exploded view of inside the valves is available to study.) They certainly are fast closing when the button is pushed.

Thank You All Again for helping and for ideas. I very much appreciate it.
Paul

 

[Jeff H Young]

hmmm sounds like it could be that valve by nature how bout your pld one? or this is a new build?

 

[PGB1]

Thanks for writing Jeff H Young.
It's a new installation. The old valve was a 3-handle Central Brass adjustable spread faucet from the 50's.

Since Grohe can't give me a definitive answer, I tried an experiment:

The supply tubing has ball valves & sweat unions about 12 pipe-feet away in the basement. I turned them off, drained water from the piping. While listening upstairs, with my hands on the valve body, someone slammed the ball valves on as fast as possible-one at a time. There was a slight sound, I assume when the water hit the closed shower valves. There was no movement or "hit" felt in the pipes.

So, at this point, I think your mention of the nature of the valve is probably spot-on.
It's too bad Grohe can't give me a definitive answer. (I think I'm at the "phone answerer" level of tech support. Maybe if I ask for warranty parts, I'll get bumped up to someone who knows the valve.)

 

[Tuttles Revenge]

We've only installed one of these type of valves in a condo.. If it was endemic to the valve itself we would have heard about it..

Where are your hammer arresters located in relation to the shower valve?

 

[PGB1]

Thanks for replying Tuttles Revenge.
The arresters are 7 inches below where the supply lines enter the Rapido smart box. A drawing is attached.
Thanks Again,
Paul

 

[Tuttles Revenge]

That seems like they should work! They're as close to the fast closing valve as possible. So then I'd be looking a what your static water pressure is set at?

 

[PGB1]

From Tuttles Revenge: So then I'd be looking a what your static water pressure is set at?
Our water pressure is 48 psi-g when nothing is running in the house. At the shower outlet, it's 46 to 48 when the tub spout is running from it's outlet.

 

[Tuttles Revenge]

ghosts...

 

[PGB1]

I apologize for not replying in a timely manner. For some reason, I don't get e-mail notifications of a reply, although I subscribed to the thread.

I spoke to someone at Grohe technical support who installed this valve in her house. After confirming the water hamer placement & size, she said the "Aquadimmers" are defective (Fifty-dollar marketing word for push buttons).

The parts are on a "5 month minimum back order". The face plate is also defective, but the backorder for it is only 4 months. So much for Grohe's warranty.

Plan B: I ordered a new complete unit and will return this one with the bad Aquadimmers. I'll post the (hopefully good) results. The bright side is that it takes about 5 minutes to change the valve.

Thanks Again for helping & for the helpful diagnostic ideas everyone. I sure appreciate your help.
Paul

 

[Tuttles Revenge]

spoke to someone at Grohe technical support who installed this valve in her house. After confirming the water hamer placement & size, she said the "Aquadimmers" are defective (Fifty-dollar marketing word for push buttons).

So basically the push buttons have some form of slow close feature that has stopped Dimming.

Plan B: I ordered a new complete unit and will return this one with the bad Aquadimmers.

They're still catching up to supply chain issues or they just havent created a well diversified stock for spares. This is exactly what I would do for a customer if we couldn't get parts in a timely manner... We had a shower trim that was back ordered and I scoured the world to buy each component separately until that shower was 100%.

 

[Reach4]

That would be under the warranty, wouldn't it be?

 

[PGB1]

From Tuttles Revenge: So basically the push buttons have some form of slow close feature that has stopped Dimming.
Good point! I never thought of that. It makes sense that they should slow-close, especially since the first person at Grohe with whom I spoke said water hammer arresters are never needed with this valve. It'll be interesting to listen to the new one when it arrives. (Short back order on it. It's due within the next 2 weeks.)

They're still catching up to supply chain issues or they just haven't created a well diversified stock for spares.
Another good point. It seems the world is still catching up from shortages of everything, as evidenced around here by auto plants cutting shifts for lack of parts (and the half empty grocery stores). These Grohe parts come form Lixil's factory in Portugal, so we can add the shipping container ports-of-entry pile up to the mix. When last I saw, the Detroit docks were stacked high with containers still left from before river shipping stopped for ice.
Such is life these days.

From Reach4: That would be under the warranty, wouldn't it be?
Per Grohe, the parts are warranty, the whole unit is not. But the original is still under the return window, so back it will go when the new one arrives & is tested.

Thanks Again to all for helping me figure out this noise problem. I sure appreciate it and will be certain to write back with results when I install the new part.
Paul

 

[Jeff H Young]

Ok I get that "aquadimmer" is a 50 dollar word . I would recomend try changing all the guts . as a wild chance it might fix it
let us know how it comes out.
BTW Depending on how you feel about grohe service , cant you get a valve in a day swap out and return for refund?

 

[Reach4]

I looked for what Aquadimmer might mean. The name implied to me that it would be a slow-close valve. I found nothing to indicate that is the case, and I now suspect that is just a Grohe brand name for a valve cartridge.

 

[Jeff H Young]

Got a kick out of 50 dollar word but PGb1 aint giving away the definition So ill just call it the guts Lol

 

[PGB1]

I'll be sure to post when the new valve arrives. What will be fun is to remove one of the push-button "Aquadimmers" and study it on the bench.