How do I replace a Grohe Compact thermostatic element 1/2" for a new model?

A common component in Grohe thermostatic faucets is the "Grohe Compact thermostatic element 1/2" for new models. We regularly receive questions about how to replace and set it. In this example, we explain this step by step using the repair of a Grohtherm 1000 Cosmopolitan. The procedure is the same for many other models. The difference sometimes lies in the construction of the handle, which is always shown on the corresponding faucet drawing.

Step 1
We have a Grohe thermostatic faucet that gets less and less hot, no matter how hot you set it. This is a sign that the element needs to be replaced, which is usually due after 6 to 12 years.

To begin, we shut off the water and relieve the pressure from the faucet by opening it and letting it run until no more water comes out. Now we need to get to the screw that holds the handle onto the thermostat. In this case (and in most others), there is a cover cap on the handle, which has a slightly wider seam on the back, allowing you to pry it off

Step 2
Now that the cap is off, we see the screw, which we unscrew

Step 3
Now that the screw is out, we remove the handle from the faucet

Step 4
Now that the handle is off, we see a lock nut. Note, this nut is very thin. If you want to start loosening it with a water pump wrench, you will be tempted to squeeze it. This will cause the nut to be squeezed into an oval shape and make it even harder to loosen. It is best to use a suitable pipe wrench, as we do, or at least a wrench that fits properly and does not squeeze

Step 5
Now that the nut is completely off, you can remove the old element by pulling it out STRAIGHT, not turning it. You will see a lug on the edge of the element; in the thread where the nut came out, there is a notch that ensures the element cannot turn and can only be pulled out straight in one way

Step 6
Now that the old one is out, we can put the new one in. Place it back into the faucet with the lug in the correct position. Once it is in place, push it in firmly, then you will hear a click and it will be deep enough to leave room for the nut.

Step 7
Now that the new element is in place and the nut has been tightened again, we do not put the handle back on immediately First, we turn the water back on. So now we have the faucet without the handle. Now turn the faucet on and turn it just as far as necessary (if needed, it is usually already fairly well set at the factory) until the temperature is 38°C (or a temperature that feels comfortable to you, which will be around 38°C).

Step 8
When the temperature is correct, put the handle back exactly with the 38°C mark in the correct position without turning it, so it is against the point where you have to press the locking button to get hotter water. Now tighten the handle again and put the cap on, and you are done