I am having trouble installing a Grohe Grohtherm 1000 mixer at a new property.

Problem is the previous owner has a marble tiled bathroom, and has installed a shower panel (one of those plastic hang on the wall.



The panel is messed up and some of the heads are badly corroded or busted. Once I took off the panel there is a hot and cold connection behind at about 12" or so above the top of the tub. I can imagine at one time there were a valve around there, a line up to the shower, a line down to the tub spout, but no more tub spout connection, there is a shower line up, but the pipe was badly mutilated and out of round. All I saw were hot and cold sticking out connection to the flex connectors to the back of the panel.

Problem is they tiled this with marble, and behind it is the exterior concrete block wall. There is no easy way for me to install the traditional spout and shower configuration. So I compromised and decided to install an exposed shower mixer.



The idea is I will then mount a shower bar, and hand a hand shower on it, they can adjust it up and down the bar, and have volume and thermostatic controls. There won't be a tub spout, but very few people take baths nowadays anyway.

So, I started to make the install. First I found some mosaic stone tiles, and mark a rectangle around the supplies. I cut the rectangle hole with an angle grinder.

Next I soldered the hot and cold and positioned them ending with 1/2" female adapters about flushed with the finished tiled surface.





They have those "S-UNIONS" that are basically offset nipples that screws into the 1/2" female connections. They are supposed to allow some degree of play with the connections. I doped up the S-UNIONS and installed them, turned them until I got the right separation for the mixer and have both of them level.

Here is a pic of this S-UNION. One side threads into the 1/2" FIP at the wall, the other side attaches to the mixer.



NOW I am trying to find two caps for the end of the S-UNIONS so I can test the pipes and fittings to make sure there is no leak. I tried hose caps and they leaked a little at the caps but this could be due to the S-UNIONS are not 3/4" or hose. Note that before connecting the S-UNIONS I already tested the line to the female adapters with 1/2" nipples and caps. No leak.

I think may be Grohe uses different S-UNIONS in different parts of the world? The male threads to the mixer connection may be "special" and the other end may be 1/2" in the US but metric somewhere else. So may be there is no way to test this without actually connecting the mixer?

Second I am concerned about the mixer's weight. It is heavy. It screws onto the two connections. There is no other anchors to the wall. Is this right? Anyone ever installed one of those things?

Here is a link to the mixer.

[www.grohe.com]

I thought German engineering is supposed to make things easy...



Edited 3 times.

quote; I thought German engineering is supposed to make things easy...


WHO ever told you that? The connections WOULD be proprietary so you have to attach the valve in order to test it.

I have mostly Grohe and Hansgrohe products and they have always been easy to install and use. This is the first one I felt it wasn't well designed because these S-UNIONS doesn't make the install easier but instead makes the depth adjustment more tricky and I believe the true purpose of these S-UNIONS are for Grohe to make the same faucet for their worldwide market but use different S-UNIONS to adapt to the different countries.

Well, if I connect the mixer to test, if there is a leak I can't tell what's leaking because the mixer will be obscuring my view all I would see is water misting behind it.

I thought if I capped the unions and it does leak I can tell what's happening. And if it doesn't leak and when I connect the mixer I know for sure the leak would be the mixer-union connections, and not the union-female adapter connections.

the purpose of the 's unions' is to enable a perfectly level installation of the 'shower bar'

the fixture end will be a proprietary thread

try a hose cap with several washers, but, DO NOT FORCE

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

bernabeu,

I will try the hose caps next. I would have tried it but the shutoff is far away and I need someone to yell at me to turn on or off in case there are leaks.

As for the S-UNIONS for leveling the install, I see your point, but it is really tricky.

FIRST, the S-UNIONS have to be threaded in, rotated in such a way, that it is perfectly level, as you said. SECOND, the final separation of the installed unions need to be exactly 6" apart, which means once you get it to be level, they may not be exactly 6" apart. THIRD, these unions have to be screwed in tight to the female adapters, and if you got it tight, further rotation to tweak the separation distance or level must be done by threading in, not backing out.

I find trying to do all three at the same time frustrating.



Edited 1 times.

us actual plumbers find it fun

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Fun? No way that can be fun.

Remember, I was squatting in the bathtub while doing this, just after using a diamond saw blade to cut the hole, with the bathroom still fun of marble dust...

not to restart with hj,

but,

if one counts turns when using NPT there is MINIMAL problem / issue

and

the 'roughing' center - center should be PRECISE so that a little up or down will not affect center significantly

one will not 'see' a little left-right error, but, one WILL see level

again:

PLUMBING IS IN FACT A SKILLED TRADE

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

I see level of the sea level last weekend, and I am not convinced it's rising.