shower mixing valves intentionally restricted?

[jadnashua]

If the flow is even between hot/cold, then the likely place, if there is any, to find debris would be the common point...the diverter.

As was mentioned earlier, you can BUY things that are not up to code, but you are not ALLOWED to install them. Seems kind of weird, but true. The plumbing code requires anti-scald technology in a shower on any new or replacement situations. You can keep an old one, only when repairing it, not when replacing it. That you've not had a situation where you needed the anti-scald feature isn't the point. Just like you can't buy a car without airbags, you may have trouble selling the house without anti-scald valves.

1/2" Pex (each line) is good for up to about 6gpm at typical pressures...more than that and you've exceeded the maximum recommended fluid velocity in the pipe which can cause problems. Tie both the hot and cold into the valve, and you may get more than 6, since you've got both hot and cold feeding into it (but you may not based on internal design of the valve).

There are numerous tub/shower valves that give you both volume and temperature adjustment that do meet codes.

[butleraudio]

Thanks for your input "j", If I sell the home, I will bring all items up to code...including the plumbing.

It would be highly unlikely that any 1 pex or poly line in my home (except for the 3/4" trunk line) would have any more than 6gpm (most likely 3.5gpm) since both hot and cold were on during the test that resulted in 7gpm. I could test the hot and cold lines separately, but as I mentioned, both are equal in flow rate. And I assume (there I go again) that even HUD code requires the heater tank have a direct feed from the main trunk.

FYI, it takes 15-18 minutes to fill my new tub to my liking (water amount and temp considered) ....that's just plain toooooo long

WOW, 12gpm would be nice!!!! fill it in 5 min!

Im just gonna get out the drill....and I will keep an eye out for the anti-scald police

butleraudio

[LLigetfa]

Im just gonna get out the drill....and I will keep an eye out for the anti-scald police

It's not just the anti-scald police you have to watch out for. It's also the water conservation guerrillas. The first thing I do when the fixture comes out of the box is to disassemble it to find the EPA mandated flow restrictors and figure out how I can defeat them.

[butleraudio]

I did a re test and here is what I got...should be a bit more accurate:
In my existing 1994 bath, with both hot and cold wide open and tank pressure at 65psi:
tub fill: aprox 8 gpm
shower pipe(no head) aprox 5.8 gpm

In my new bath, same conditions:
tub fill aprox 4.6
shower pipe aprox 3.9 gpm

and yes, I did confirm that both hot and cold are equal; 3.3gpm for either by itself (4.6 for both) with the new tub fill, where as in my old tub the flow rate of either single line is aprox 4.5gpm. So with a diverter that does nothing but divert, I would expect at least 6 gpm with the new rig.

so if I pull the diverter stem out, cap the hole, and replace the tub spout with one that has a shower diverter built in...(I assume that is only a shut off for the tub spout?)...I should get 6gpm......hmmm, that's still not enough. And it looks like the shower pressure is 15% of the tub fill and 25% in my old bath (which uses a tub fill diverter)....I did not expect that.

All I am asking is to enjoy the same shower pressure and the same tub fill rate as I did before renovation.
butleraudio

[jadnashua]

As you've found, not all valves are created equal. Then, you used pex, which in itself is not necessarily bad (I've got it in my bath and my 6' soaking tub takes about 8-minutes to fill), but if it uses the insert and crimp style, each connection creates a moderate restriction. The ID of 1/2" pex is closer to 3/8" copper, especially after you throw a connector or two in the water stream. If you want max flow from what you have, then copper would have been a better choice, or larger diameter pex, or pex that uses the expansion system to make connections (the fitting ID is larger) or a 3/4" valve, some of which are rated at 17-18gpm. the area of the pipe opening is pi*r^2, so a little increase in diameter makes a big difference in the amount of flow available and less restriction to maintain the pressure during flow (static pressure is the same regardless of the diameter).

[butleraudio]

Problem solved, I hope. I have purchased a Kohler K-303-K-NA valve and the appropriate handles. This is a three handle 1/2" mix T, 1/4 turn ceramic stems, and push pull diverter. This unit is rated at 10gpm. So we'll see. I will post a follow up once installed.
thanks all, butleraudio

[hj]

1/4 turn ceramic stems are a flow restriction, by design.

[butleraudio]

Kohler SAYS that this valve will do 10 gpm at 45psi, however, my local plumber does not like Kohler valves...says they wear out to fast and are expensive to replace parts. The second issue I can maybe live with.

So far, I have not found a 3 handled 1/2" valve (mixT) with that kind of gpm rating in another brand. Do any of you have an opinion of Kohler valves?

Also, what should be the going rate to remove existing valve and cut in the new one...valve only (tub fill and shower riser remain). It's all 1/2" and the holes line up. And yes, there is an access panel.
Thanks, butleraudio

[jadnashua]

A plumber is ethically required to do this to code...a three-handle device is not to code. WIll you find someone that will do it, probably, there are a bunch of them whose ethics may not meet standards. You'll find lots more choices in code approved valves. With good access, it's probably not more than a couple hour job...depending on local rates, you should be able to make a guess yourself.

Kohler makes some nice stuff, but they are IMHO, saturated with NIH syndrom and I can do it better freaks. As a result, their parts book is HUGE, since many things don't stick around for long. This can make it difficult to find the proper part, and may be impossible if you didn't save the original instructions and diagrams with part numbers. This, as opposed to say Delta, that uses a few internal designs and parts are readily available both OEM and aftermarket (since there's such a large quantity out there it makes it reasonable for an aftermarket supplier to take notice and provide parts).