Problem with Grohe Grohmix Thermo valve?

mrvf · Nov 16, 2011

Hello, I have a Grohe Grohmix 19229 shower faucet with a thermostatic valve 34419. It was initially installed in 1996. Gradually, over the past few years the handle became harder and harder to turn. As of the other day it became loose and spins but does not change the water temperature - you can feel that there is no grab. I've taken it apart and cleaned the pieces with a vinegar solution. I cannot remove the cartridge â€“ it is stuck. The shower has no leaks or drips. The pressure is fine. There was no moisture inside the wall when I took the faucet apart.

I checked that the pieces I could remove were intact the teeth on the stop ring are intact no threads stripped, no cracks. When I put the faucet back together the same thing happened and the handle is loose and doesn't change the water temperature. I tightened the handle screw but it becomes loose again after a few turns.

My question is, is this a cartridge issue? Or do I just need to replace the other parts like the plastic thermostat handle?
Thanks

Jadnashua · Nov 16, 2011

Don't know, but I think I'd just call Grohe and see what they think.

Sponsor · 2022-01-29T12:20:58-0800

mrvf · Nov 17, 2011

Thanks - I was able to figure it out, though.
It's fixed now and working fine.

santa608 · Apr 21, 2012

I am desperate!

mrvf said:
Hello, I have a Grohe Grohmix 19229 shower faucet with a Â¾â€ thermostatic valve 34419. It was initially installed in 1996. Gradually, over the past few years the handle became harder and harder to turn. As of the other day it became loose and spins but does not change the water temperature - you can feel that there is no grab. Iâ€™ve taken it apart and cleaned the pieces with a vinegar solution. I cannot remove the cartridge â€“ it is stuck. The shower has no leaks or drips. The pressure is fine. There was no moisture inside the wall when I took the faucet apart.

I checked that the pieces I could remove were intact â€“ the teeth on the stop ring are intact â€“ no threads stripped, no cracks. When I put the faucet back together the same thing happened â€“ the handle is loose and doesnâ€™t change the water temperature. I tightened the handle screw but it becomes loose again after a few turns.

My question is, is this a cartridge issue? Or do I just need to replace the other parts â€“ like the plastic thermostat handle?
Thanks

I have the same problem. My faucet was installed in Buenos Aires. I took it apart, and I think that the plumber when he installed it broke the green screw adjustment. and jury rigged it so that it worked for a while. How does this value work? The direction talk about adjusting the temperature with a screwdriver. but that is impossible. Ihaven 't hada proper shower in a week. Thanks

Jadnashua · Apr 21, 2012

The internal adjustment is to calibrate the temperature readout on the handle to the actual temperature...this is normally done at the factory, but should be checked by the the installer. While I don't know, my guess is that the cartridge is toast and needs to be replaced. Does Brazil have a Grohe national rep? Call them, or you might try their distributor via e-mail (may or may not be fruitful).

GB26 · Apr 1, 2024

mrvf said:
Hello, I have a Grohe Grohmix 19229 shower faucet with a thermostatic valve 34419. It was initially installed in 1996. Gradually, over the past few years the handle became harder and harder to turn. As of the other day it became loose and spins but does not change the water temperature - you can feel that there is no grab. I've taken it apart and cleaned the pieces with a vinegar solution. I cannot remove the cartridge â€“ it is stuck. The shower has no leaks or drips. The pressure is fine. There was no moisture inside the wall when I took the faucet apart.

I checked that the pieces I could remove were intact the teeth on the stop ring are intact no threads stripped, no cracks. When I put the faucet back together the same thing happened and the handle is loose and doesn't change the water temperature. I tightened the handle screw but it becomes loose again after a few turns.

My question is, is this a cartridge issue? Or do I just need to replace the other parts like the plastic thermostat handle?
Thanks

How did you resolve your issue? Mine is doing the same thing. Handle screw becomes loose again and again. I took apart the handle of the exact same model on another shower that was working fine (trying to figure out the first handle!!) and now that handle screw becomes loose too.

TJRAD · Apr 2, 2024

The Grohe thermostatic cartridge should be replaced. the part number of your cartridge is stamped on the face like my picture below. The handle interfaces with the cartridge by friction fitting over the tapered stem. When you tighten the handle screw you are forcing the handle further down the taper. When the cartridge is new the handle effortlessly rotates . Be warned that this is probably one of the most complicated valves a plumber could ever work on. If you higher someone make sure they are a plumber with experience with Grohe and not your gardner who says he can do it. Not sure which valve trim you have but here is a picture of the most common from back in the day.
Good luck.

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Problem with Grohe Grohmix Thermo valve?

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