Kohler Shower valve diverter malfunction mystery

The Problem: Pulling the tub spout diverter up to engage the shower head results in a moderately loud vibrating noise and water is split between both outlets. Vibration is hard enough to rattle the pipes and can be heard throughout the house. Not as bad as a toilet water hammer though.

Long story short discovery: low water pressure at the shower valve causes the problem.

Question: What can I do to correct this problem - given all the solutions already tried (see below).

Longwinded background/info:

I recently remodeled (2014) a standard 8x8 bath - call this the MAIN bath. Cast iron tub with Kohler K-304-K valve and Forte Trim. Half inch copper supplies. The Forte shower head was replaced with a Water-Pik hand held shower handle. The previous valve was a Simmons, with diverter handle on the valve trim. This is the bathroom with the problem. It is on the nearest water line branch from the well tank.

In 2013 I remodeled another standard bath in this house - Call this the KIDS bath. Same specs: Cast iron tub with Kohler K-304-K valve and Forte Trim. Half inch copper supplies. The Forte shower head was replaced with a Water-Pik hand held shower handle. The previous valve was a Simmons, with diverter handle on the valve trim. This bathroom does not have the problem. It is the furthest water line branch from well tank.

The problem happened in the MAIN bath right away. The problem does not happen in the KIDS bath.

Pressure observation: It seems that if the water pressure at the problem valve is below 30# when you try and engage the diverter the vibration problem happens. If the well tank is more on the fully charged side of things it doesn’t happen - works great. So it is just dumb luck whether you get in to shower and the well tank is near the kick-in point.

Pressure tests: Using a screw on pressure gauge on the threaded faucet on the Laundry sink (furthest fixture) I read Kick-in at 20# and Cut-out at 52# with the softener loop on. I get 25# - 50# with the filter by-pass on.
Using the same gauge at the well tank drain valve I get Kick-in at 42# and Cut-out at 62#. The well tank gauge reads 38# - 64#.
(A 5# drop through the softeners does not seem bad to me for a 15 year old system.)

Plumbing system: Starts on far left side of 34’ 2-story house with a well tank (Amtrol WX-203, 1” input, 1” output, 40/60 pressure valve), 90’s up and then double-Ts for Water Softener loop with shutoffs and by-pass, then T’s for ¾” line to tankless hot water coil on a Burnham boiler - and ¾” line to house for cold, 90’s to follow center girt with hot water line, first T up for 2nd floor MAIN bath, 4 feet later- T over for Kitchen, then near end of house- T up for 1st floor Half Bath, then at end of house 90s up to 2nd floor KIDS bath and Laundry Room. The Laundry Room slop sink is the furthest fixture on the line.

Things I have done:
o Called Kohler and they sent me out a new spout (free of charge). I’ve got 3 spouts, so they must have done that twice. No change - all 3 spouts.
o Got Kohler to send me a new Valve Kit and Pressure Control Unit (Again, no charge - great company). No change.
o On advice of my plumber, removed valve and pressure unit, closed the curtain, and turned the water on to blow out the pipes - in case there was any debris in the line. Thought this worked for a bit, but, no change.
o Cleaned (flushed) out the well tank of sediment.
o Replaced the pressure switch and gauge on the well tank.
o Tested the shower with the Kohler shower head instead of the hand held. No change.

I’m out of ideas. Does anyone know what may be going on here?

How much air is in your pressure tank when water is drained off?

Oh, Sorry. Yes I had checked that. It is 30psi drained.

I'd make sure the system has proper hammer arrest installed. Double and triple check the valve is installed properly not upside down or something crazy. Your discription sounds like you've narrowed it down to a pressure issue at that particular fixture, if that's true can you read pressure at fixture when issue is occurring, if it is pressure to a single fixture closest to the supply is it possible a kink in one of the supply lines is limiting pressure to the valve?

Has nothing to do with Kohler. I have a moen and the tub spout diverter sings to me often. I just tap it and it stops.

Thanks for the replies.

The problem has less to do with the vibration and more to do with the failed diverter. When it happens the water does not come out of the shower head normally and can't be used that way.

I mentioned the vibration, and the fact that it is similar to, but not as bad as, a WH in case that helped identify a known problem.

Kaorder59 said:

Your description sounds like you've narrowed it down to a pressure issue at that particular fixture, if that's true can you read pressure at fixture when issue is occurring, if it is pressure to a single fixture closest to the supply is it possible a kink in one of the supply lines is limiting pressure to the valve?

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I built this house and I did the reno/addition so I am very familiar with the condition of the pipes. Everything is straight pipe and fittings, no bends.

We do have high minerals in the water, so a build up of scale could be a problem I guess. But I've never seen so much it choked off a 1/2" pipe. Have you?

Does anyone here know how the Kohler 304 diverter works?
I know that when you pull up on the handle on the spout it blocks off the outlet out of the spout creating a back pressure up the spout supply, which triggers the diverter to run water out of the shower head supply. But I can't see any mechanism in the valve body that handles this chore.
So how does it work?

An exploded view of the valve showing that mechanism would be cool. I've got exploded views of the valve for parts, but that is not what I need here.

This was a 3/4 brass nipple we found in a homes water heater. Customer complained of no water pressure to hot water fixtures. This was not a dielectric and the build up had nothing to catch on, no screen or anything like that, it was just a straight brass nipple. I do remodels myself also and a couple months back I don't know what I was thinking but I plumbed in a shower valve upside down. Didn't find out until I caught it prior to the final, but it was causing similar issue. I don't know what I was thinking obviously jumping from task to task I messed up, luckily it only cost me some sheetrock work in a closet. Ill look deeper into that diverter and see if I can come up with anything.

That is amazing! It looks like sediment. Did you ever determine what it was?

I had my plumber install the valve and the tub. And we know that plumbers never make mistakes!

But when I was replacing the internal parts I was pretty sure everything looked right side up (but you know I'm pulling the trim and checking tonight, don't you!)

I do not know all the nuts and bolts on how the diverter works exactly so I would like to see a more detailed explanation if any one is willing to give us one. In my thought process is the valve limits the water pressure to a certain flow rate say 5gpm. When you activate the diverter which is on your tub spout this blocks the water from coming out of the tub spout, this increase in pressure then follows the path of least resistance to the shower head. The diverter is in the spout and is not a piece inside the valve itself. So if this is true then your diverter in the spout and or completely replacing the spout assembly will solve the issue. The first post said when the diverter is activated water is still coming from the spout this shouldn't be the case if the diverter is creating the proper sill on the the spout stub out. Following that same logic if there is a restriction in the valve body or shower head vertical supply this would cause an increase in pressure that the diverter is not capable of stoping and allowing some water to escape both the diverter and head. Again this is based more on my logic and personal experience and I don't know the true mechanics behind valve design or diverter design and would like to see additions and or corrections to this explanation.

Me too.
I've tried 3 different spouts with no joy. And I've tried my thumb.

I've also switched the shower head, and tried with no head.

I scraped the build up out to see what it was collecting on. I also removed the other nipple which appeared to be matching and had same amount of wear so I assume they where bought and installed together. I didn't find anything in the affected nipple and the other was also just a straight nipple nothing special. That has been some time ago I don't remember if it was on the in or out side but only one nipple was affected. Once fully removed I held it up to light and the hole through the build up was so small you couldn't fit a sewing needle though it, and the build up was rock hard.

As to the shower valve its embarrassing to admit but it did cause similar issues as your describing, and of course it took me three hours of taking every little piece of the valve apart and beating my head against the wall before the idea even crossed my mind, I proceeded to tucking my tail between my legs, swallowing my pride, and explaining it to the GC on the job. I paid for my mistake and learned from the experience. During that three hours of diagnosing the problem I tried flip flopping the internals every which way, I put in the cartridge and all internals in right side up originally changing the orientation did not solve the problem.

Addition: The only difference in my scenario to yours is the property water supply. My property was on city water, so I had no pumps or wells to deal with. I work in a large city so my experience with wells is limited at best, I refer well and pump specific work out.

I'm definitely going to check it out. Thanks.

I believe the valve is installed correctly.

If you look at the spec sheet for the K-304-K you can see an extra hole at 10:30 on the housing cover. My valve has that plastic guide pin in the correct position.

That is correct there is an extra hole in the metal collar that a plastic pin protrudes from the plastic backing plate. Ive never touched this model before so Im going off of Kohlers diagrams and spec sheets. According to the spec sheets this valve can be reversed if used in a stand up shower, so the backing plate would have to be able to go on both ways. If the valve body itself is upside down in the tub configuration you have it that may be the issue. If the gpm per outlet were the same this shouldn't make a difference but again according to kohler the gpm for the spout is 5gpm and the outlet for the shower head is 4gpm, so this difference could be the problem if the valve body is in the stand up shower configuration.

SHEPLMBR said:

I have a moen and the tub spout diverter sings to me often. I just tap it and it stops.

Click to expand...

That's how I stop my wife from singing too!

Originally Posted by SHEPLMBR

I have a moen and the tub spout diverter sings to me often. I just tap it and it stops.

Click to expand...

Matt30 said:

That's how I stop my wife from singing too!

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Whenever I try to tap my wife, she raises HOLY HELL...

Then she starts to giggle... then I start to giggle... then I begin to cry a little...

Here is the best explanation I have found. It is from another forum so I will post the author's name but not website to give credit where due-

Your style diverter is a a TEE DIVERTER (on tub spout);

Author: hj (AZ)

The pressure of the running water keeps the diverter shut. When the water turns off the diverter opens and lets the column of water drain out. (If the column were keeping the diverter closed it would not open until the column drained enough to release the pressure.).

There are many ways to pipe the shower. in the old days, we used a "twin ell" which had three ports, i.e., valve, shower, and spout. Then some companies incorporated the diverter into the valve, but they were fairly short lived, expensive, and time consuming to replace. Now, most valves have the "transfer" port from the diverter to the shower inside the valve with a diverter spout to stop the flow to the tub.

Dynamics dictates that this "transfer port", as it was on the twin ell, be smaller than the one to the tub to control back-flow from pressure variations. This automatically reduces the amount of water going to the shower, so, in a shower only installation, using the tub port for the shower negates the flow through the transfer port, AND gives maximum flow to the shower. If the valve is 180 degrees symmetrical, it can be inverted to do this, otherwise the tub port is piped around the valve up to the shower or combined into the pipe from the shower port to the head.

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Author: m & m (MD)

It's simply the weight of the water column that locks up the gate on the spout to hold it in place. It's not 100% shut-off so that a small trickle of water continues to come out the spout. That way, it maintains the same temperature as what is being used on the shower head to avoid scalding when redirected back to spout use.

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Kaorder59 said:

That is correct there is an extra hole in the metal collar that a plastic pin protrudes from the plastic backing plate. Ive never touched this model before so Im going off of Kohlers diagrams and spec sheets. According to the spec sheets this valve can be reversed if used in a stand up shower, so the backing plate would have to be able to go on both ways. If the valve body itself is upside down in the tub configuration you have it that may be the issue. If the gpm per outlet were the same this shouldn't make a difference but again according to kohler the gpm for the spout is 5gpm and the outlet for the shower head is 4gpm, so this difference could be the problem if the valve body is in the stand up shower configuration.

Click to expand...

So, is there an easy way to tell if the valve is installed right side up? Or is the only way to open up the rear wall?