So I have a single handle shower made by Kohler that is only 2 years old. I have regular water pressure from the tub faucet but the shower when turned up hot has a diminished flow. When you turn the sink or flush the toilet in the same bathroom the pressure is actually much better. I adjusted the temperature control counter clockwise and it helped somewhat. I also cleaned out the shower head. I keep reading about shower valve cartridges - what are these? Where would I find one? Does anyone have any other suggestions that I could check on my own before calling a plumber?

Moonpie803 - Seeing as how you don't know where the cartridges are at I think that you need to call a plumber, if you take the faucet apart to repair it you will have trouble in getting it back togreather, I'm afread, more then likely you have some trash in side from your hot water tank . One thing that might help is to hook a water hose to the drain at the bottom of your hot water tank and flush it out, getting out rust a other stuff trapped in it , its good to do this about every 6 months. Before YOU START <( DO TURN THE POWER OFF TO THE TANK TO KEEP FROM BLOWING THE HEATING ELEMENTS ) Let the tank drain then turn water back on to the tank and flush more NOTE ( NOW when you are filling the tank again ,turn the faucet on in the kitchen sink and have someone watch it to tell you when you have a good flow comeing out ,then you can turn the power back on . Good Luck & GOD BLESS ::: F.B.E.

Hey Moonpie:

One easy check is to remove the shower head and look inside and see if there is a black o-ring with plastic sleeve inside. This o-ring is there to reduce the volume flow to 2.5 gallons. If you remove it, you may see an increase in volume that you are looking for... Of course, you may not... ;)
To remove o-ring take a sharp knife and pry it out at edges.. then re-install and see if that helped (can't really hurt to remove this... most of my customers ask me to remove it and never had a complaint).

Now, if that does not do it for you... you can check out the kohler site. I typed in coralais faucet (most popular kohler valve for years) at the site and the valve and valve body parts popped up. That may help you or the plumber if you need him.

Check the link below... let us know what you decide... good luck... Mark

Kohler Plumbing (http://www.kohlerserviceparts.kohler.com/ServicePartsPage.aspx?DocumentID=1dbf521bacbf415f9 8717ef71561f66e&ModelID=0179e7cc8e18446cb03e0bf25c3bcdb4)

Use the zoom feature and orange arrows to move around the interactive page.
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Ok I figured it out. I have single laver kohler shower. Same problem I didn't have hot water pressure. So turn of the water. Unscrew the handle. Once the handle is off u will see mixing valve. It is attached by 2 screws. Unscrew it and pull , it should pop right out. Next you will see a (usualy black) PBU unit. It is right behind the valve. It has two holles. Just pull it out no screws holding that thing. That is your problem. PBU= pressure balancing unit. I took it a part. Its simple, inside there is a sort of a round metal disk with rober on top edges. The disc and robbery substance are all corroded. And that's why its not working. And u can't change the rubber, its not oval ring its attached to it perm. Or until it's corroded. The new PBU unit costs between 30 and 47 dollars. I tried to locate just a disk, with no luck. Home depod does not have it! I have ordered new PBU unit and in Maine time I took disk out of it. So it works, water kind of goes from colder to wormer but its good enough to take a shower, till I get new unit. Good Luck. Sorry for the english, I am russian =)