Grohe Shower Not Regulating Temperature

[Douglas Fifield]

Hi Folks. I'm a newbie here.

We have a Grohe shower control in our master bathroom. It's a two knob control. The top regulates the water volume and the bottom regulates the temperature. It was installed about 12 years ago and worked without problem until about a year ago when the temperature control started to lose functionality. Most commonly these days when I get in, I turn the temp control all the way to the cold side and turn on the water. It is frequently too hot to get under the shower head for the first several minutes. Then it normally moderates and becomes more comfortable and then tepid. If I turn the temperature control up in heat as the actual temperature drops, I usually find a comfortable mix. Today however, it never cooled down. Even with the control turned hard agains the cool setting, it remained too hot to endure. I have not attempted to disassemble anything yet. And while not a plumber, I do moderately well with home repairs if I have some guidance. That is what I am seeking here. All suggestions welcome.

Douglas

 

[Jadnashua]

It sounds like you have a thermostatically controlled valve. If so, sounds like you need a new cartridge. They do eventually wear out. You could try pulling it out and smearing the surfaces with silicone plumber's grease, but that may not help. At least it won't hurt. Grohe considers this a normal wear item, and not covered under warranty, so you'll have to buy a new one. Almost $200 or so. I need to replace mine, as it's really slow to adjust, but have been putting it off. If you don't have the original installation instructions, you may be able to look them up on their website, or if discontinued, they may be able to help you discover the model, and email you a PDF. Once you install the new one, you do need to follow the instructions to calibrate it.

If it's just a pressure balanced valve with volume, temp, the pressure balance valve may be sticking. Sometimes, taking it out, cleaning and lubricating with the plumber's grease can restore it, but often, it requires replacement. That part, though, is generally fairly inexpensive depending on whether it's part of the volume control or not.

 

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[Fitter30]

This site shows a lot of valves if you don't know the model number. Then see what youtube has for a video.
https://www.faucetshark.com/Grohe-Repair-Parts-Guide-s/6621.htm

 

[Douglas Fifield]

Well folks, the handle cover is off and the shell over the cartridge is off. I am not sure how to remove the center part which I assume is the cartridge. There is a spring clip visible, but both pushing it in and lifting it partway out do not seem to free the cartridge assy. Here I sit. Any suggestions?