Grohe 34126 thermostatic valve problem

**jalmora** · 03-07-2013, 10:27 AM

Hey there. I purchased a Grohe 34126 thermostatic valve in 2006. Installed in 2009. Been just fantastic all this time, but recently I am unable to get really hot water, the kind that makes you want to stay in the shower. I can get hot hot elsewhere in the house, but not the shower or tub. It hits a certain moderate temperature and will not increase. A lot of the info I find out there is for new installs, but mine was working just fine and only recently has been a problem. Any ideas? Thanks.

**jadnashua** · 03-07-2013, 12:19 PM

YOu may need to check the inlet filter screen or check valve for crud...it may have a restriction, preventing it from getting more hot into the valve. IF that doesn't fix it, it may need a new cartridge.

**jalmora** · 03-07-2013, 03:52 PM

Total nonplumber here. What do you mean by the cartridge? I won't be doing this myself, but am trying to gather information for the nice guy who will. Thanks for responding, btw.

**jadnashua** · 03-07-2013, 04:14 PM

The moving parts inside are typically called a cartridge and are replaced as a unit. Many of the Grohe valves have a little set of checkvalves in them - those have a small moving part, and a filter screen. If that gets jammed up, it will disrupt the flow. Same thing with the inlet filter screens (most of the Grohe valves use them). If you're on a well, you may have some occasional sand that gets in the system...that could clog some things up eventually. It could come through the town's water system, but isn't as common.

**jalmora** · 03-07-2013, 04:56 PM

Thank you Jim.

**jalmora** · 03-15-2013, 08:40 PM

If this double posts, sorry. We received from Grohe and installed a new cartridge. We cleaned the filter screens. Now we get scalding hot water for the first approx 5 seconds before it adjusts to that same "just below comfortable" moderate setting. We can get very cold water on demand, but not that good shower temperature. Any ideas?