Grohe shower valves

Ken C.

I hate to ask a plumbing question in a heating forum, but figure it's worth a shot. I'm a plumber who has been asked to install a Grohe shower valve (I've installed a ton of Symmons valves, but never a Grohe). This is a complex install, with a thermostatic mixing valve, four volume controls, a waterfall shower head and multiple body sprays.
Even if no one here has ever installed a Grohe valve, I'm hoping that maybe a Wallie can at least refer me to someone who has experience in this type of install, or point me to some other resource. I've already tried the Grohe website, but didn't find it helpful. The instruction with the rough-in valves contain no piping diagrams, which is what I'm looking for help with. Thanks.

shawn_5

grohe

make sure the valve is big enough for all those shower heads I think the biggest they go is a 3/4 inch valve which I think is 8 gallons per minute. I have got grohe pamphlets at my supply house which has diagrams in there good luck
shawn

rich pickering

Be real careful with the rough in dimensions. Best thing is to take the rough-in and the trim to double check the dimensions.

b young

Grohe valves

We have installed a few of the 3 wall and ceiling systems. Grohe makes a book for roughing it in which should be availble through your wholesaler. Hint. You need to go through your mixing valves first and then to your volume controls. If you have body sprays you need to build a loop to keep equal pressure at all times. Get a hold of the book before you go any farther. It is a snap with the diagram, but they do take some time.

jesse the great

valve rough ins

use the 3/4 inch thermostic mixing valves. on these know your finish thickness, on the valves plastic cover they show you where they line up with the finish walljust set it to that .on the divirter valves make sure that the stem is 3/8" beyond the finich wall. ohh and plan for a full day for piping 100% no bull

Mike T., Swampeast MO

The main thing about piping a big shower system is to use pressure-balanced loops just like used in irrigation systems. These loops ensure that pressure remains constant at any point in the loop regardless of the volume of water being delivered.

Your first loop encompasses all of the volume controls served by that thermostatic mixer. Then use additional loops for any volume control serving more than one output--e.g. those body sprays. If using more than 1 body spray on a volume control, I suggest the ¾" version; ½" is fine for a single output.

Photo shows the loop I used. Don't get the idea that you can increase flow by using both of the outputs on the mixing valve--it won't work. Use only one (believe it's always the bottom or tub outlet with all Grohe ¾" bodies.)

This ¾" valve serves one shower head (on "champagne"), five body sprays and one hand-held simultaneously with only slight drop in delivery pressure.

The valves all come with "plaster shields" to aid in making your holes the proper size. Make CERTAIN you use them. The instructions with each valve give allowable dimensions regarding setback from the wall--quite generous by the way.

The body sprays (at least the model I used) are another matter... Use UTTER precision. I highly recommend diamond hole saw bits. Use them in a drill press and get some florist's clay. Make a dam around the hole with the clay, fill with water and drill away. Plan carefully--do your utmost to avoid locating a body spray over a grout line. I used a good plumber's epoxy to secure the male adapters for the body sprays to the cement board. You do get a bit of "in-out" adjustment with the body sprays, but no lateral adjustment whatsoever.

Weezbo

Ithink they are indeed fine valves....

they are sorta PITA to deal with however, the rough in is important as the finish trim aint all that forgiving.........same goes for their whirlpool jetted tub lash ups. are you having Plenty of hot water at theright flow rate making it there? is big deal.

Ken C.

A few more questions, Mike

Thanks for responding to my plea for help. You did a great job on your install.

Most Grohe valves are installed in a custom-tiled shower stall, but my application is unusual - I will be installing one in a three-piece fiberglass tub-shower unit (a cheap $300 unit, no less - I kid you not!)

1. My install will likely include a tub spout. I assume that will need its own volume control. The rough-in instructions mention something about a bypass or a twin ell when using a tub spout, but I have no idea what they mean. Can you shed any light on that?

2. My body sprays are different from the ones you used. I will be installing one externally-mounted bar, with inlets at each end. The bar has five spray outlets. I guess the bar will act as a loop, no? Also, I will need to use 3/8" drop-ear 90s, but cannot attach them to the thin fiberglass. I guess I'm in for a lot of wooden bracing.

3. Why does the Grohe valve have two outlet ports, when it is recommended that only one of the ports be used? Or, should I use the top outlet for the shower head and body spray bar, and the bottom outlet for the tub spout? Should the tub spout be part of the primary loop around the mixing valve?

Mike T., Swampeast MO

Use only ONE outlet. Two are provided to give some latitude in piping. Make utterly certain that you connect "hot to hot" and "cold to cold" (the valve body has the letters "H" and "C" in the casting on one side and the German initial for "hot" and "cold" on the other.) Don't get confused!

The "twin el" is a freaky little piece that installs right behind a DIVERTER-TYPE tub spout--it allows you to use both a filler and a shower head with a single volume control.

In your instance, I'd use a plain (non diverter) tub spout with its own dedicated volume control. Just consider it another outlet off of the loop.

Haven't used that type of body spray bar. If it has only one inlet, then it likely has a built-in loop. If there are inlets at top and bottom, then I'd bring them together through a tee and run the branch to the volume control.

Have done one simple Grohe install (mixing valve, volume control, shower head, hand-held and diverter) in a fiberglass shower only. Yes, LOTS of bracing, straps, etc. Hopefully you have easy access to everything!

I enjoy working with Grohe but you DO have to be very careful with your measurements and plan things thoroughly.

One other thing: all mixing valves may not have this, but if you see a piece of styrofoam that fits inside the cover plate, it is NOT packing material! You'll find a rectangular neoprene strip that fits into a groove around the top and sides--don't forget to install!!!

(Sorry if I seem to be saying the obvious about "hot" and "cold" and that gasket. I had to re-do a Grohe install by the "best plumber in town" and noticed these problems.)

Scott Denny

Extensions

If you do make a mistake (or the tile, stone people float too thickly) on your rough-in depths, Grohe, unlike some manufacturers, makes extensions. One point I try to drive into my guys when they are roughing in body sprays is to set all female adaptors at the same depth. Being off by as little as an 1/8" in depth might be something the HO could notice.

bob young

technical plumbers

1/8 " ?? do they use michrometers ? lol sylvan would be proud,Scott.

rod robbins

I just did a grohe job in my own house and admire the quality.I have all 3/4 and can run most everything at the same time.The only real caution as stated in other post is the rough in depth.Grohe has one 1 1/2 extension if your to short.I found that i had to extend most of the valves because i used granit over 1/2 cement board with heat transfer plates behind the cement board.If you get the vaves and the trim prior to install and asemble a valve you will see were you need to be.

Ken C.

To play it safe,

I will tell my boss that I want all the trim and accessories before I attempt to rough in the valves.

mp1969

Grohemix

Grohemix thermostatic units usually are installed before the individual valves that go to various locations.
Down stream from the mixer is where you install the control valves to the various heads 'spouts etc. We do not use twin ells or diverter spouts. You will want to make certain what the minimum temperature requirements are for the Grohemix! I have run into minimun 140' F valves that will not work as they have limit devices engineered around this temperature.
Labor increases dramatically with the install of these valves and quite frankly this sounds like a miss application. The owner should consider a tile or thicker paneled enclosure for this high end valve (that is why they have plaster caps etc) The thin charecteristics of the fiberglass unit will require even more labor than the normal tile,marble or composite installs.
Unless I had a not to exceed price that was inflated to cover the unknowns I would most certainly do this on a cost plus basis!
We install probaly 4 or 5 of these every couple of weeks and we find them a very well build, well engineered and high quality valve. Grohe has a great product at a premium price but still lacks easy parts availability.
Our supplier claims that the parts are sent via container shipping.(This has resulted in 6-8 week waits for parts)
High end user love the Grohe line but are not the type to wait for parts.
If anyone can enlighten me regarding qicker access to Grohe parts I would make alot of our customers happier!

Great posts!

Thanks for a plumbing question it seems to create further diversity in this already top shelf forum!

MP1969 rkontny@charter.net