Repair, fix and maintain Grohe flush system
Grohe cistern repair
Fix and maintain Grohe toilet flush system
Grohe dual flush / concealed cistern systems are worldwide known for their quality and reliability. Grohe systems are maintenance free and works for long time without any service.
Tip: In many countries Grohe warranty is valid for 5-10 years.You better first check if your warranty is valid and use it prior of following this guide.
After several years of using Grohe system, especially in a high calc level of water (=hard water, = water with high mineral content) and due to material aging, some de-calc, cleaning, maintenance and possibly gasket replacement might be required.
Grohe concealed cistern design is sophisticated and was made so tight that some guidance in needed on how to take it apart in order to perform a cleaning, repair and maintenance process.
When I searched for information on how to repair or take it apart, I have found very little information so I have decided to create my own guide to help you out in the process of taking apart this system. Enjoy it.
DISCLAIMER – Important!
Please note:* This guide shows the Grohe GD2 system, cat. # 38642 000 but it might also help with other models as well.
** In this guide the float valve location is on the left side. Since Grohe system was designed symmetrically, it can be located on left or right depends on your water supply installation.
* Don’t worry, it is easy to gain access to Grohe cistern parts. There is no need to break tiles or wall to do so.
Accessing the system is done through the access panel which is found under the actuation panel.
a: Disassemble according to the following guide.
b: Clean parts from calc buildup, dirt, sand / small stones etc.
Tip: You can gently brush the parts under running water.
To get into hidden places, best and cheap way is to soak parts in a Citric acid solution. (use 1 full teaspoon for every liter of water). Citric acid powder can be purchased in every grocery store. Let it soak for a few hours to remove all calc.
Tip: When done cleaning and prior to assembling, I advise to test moving parts and make sure it moves freely.
c: Replace any required / fault part.
d: Assemble all parts in reverse order to a. above.
A. Pneumatic actuation plate
B. Water filling float valve
This sub-assembly consists of 2 main parts and additional parts that needs cleaning.
C. Stabilizing bracket (frame)
D. Pneumatic discharge valve (drop-valve)
This sub-assembly consists of 3 main parts and additional parts that needs cleaning.
Its lower part (the rod) holds the silicone seal that opens the water flow of the flush.
Grohe GD2 assembled parts outside the container
Grohe GD2 main parts
* Image shows assembled parts outside the container
Note: Clicking on each image will open a bigger image.
Grohe Actuation plate removal
Actuation plate removal
Push the lower part of the plate a bit up (1) and than rotate its upper part towards front (2) to release it and taking it off.
Tip: Take it off just a few centimeters as 2 air hoses are connected to it.
Grohe Water supply turn OFF
Water supply turn OFF
Use flat screwdriver and turn it CW
Grohe Discharge water
Discharge water
Grohe Air hoses disconnect
Air hoses disconnect
Place the actuation plate aside and keep its front plate from getting damaged / scratched.
Tip: Mark the actuation plate so you’ll know which hose connects to each button connector. Note that though this plate consists of several detachable parts that can easily be replaced, Grohe does not sell any of it. You’ll be offered to replace the full subassembly panel which costs a lot. Grohe unfortunately does not care about the environment and sustainability matters when it comes to its own parts.
Just in case you got those parts, here are some disassembly images that might help.
a. Press 4x snaps aside to detach the buttons from the plate
a. Press 4x snaps aside to…
b. This is the detached parts. Each button is held by 3 Black snaps.
b. This is the detached parts…
Grohe Small button parts
c. Small button parts
Grohe Large button parts
d. Large button parts
Grohe Frame removal
Frame removal
Grohe Water supply hose disconnect
Water supply hose disconnect
Turn ring CCW by hand. Move the hose end to the side of the cistern.
Grohe Water float valve disconnect
Water float valve disconnect
First push the latch up (1) and while holding the latch, slide the float valve towards the center (2).
Do it while turning it along with pulling it out.
Grohe Remove the float valve step a
a. Pull and rotate
Grohe Remove the float valve step b
b. Continue to pull and rotate
Grohe Remove the float valve step c
c. Continue to pull and rotate until removed
Grohe Remove the float valve step d
d. This is the float valve outside the cistern
a. Squeeze snap (1), pull tab (2) remove the float (3)
a. Squeeze snap (1)…
Grohe Further disassembly step b
b. Unscrew spring cap
Grohe Further disassembly step c
c. Remove cap
d. Remove inner (red) part with membrane (pull out)
d. Remove inner (red) part…
Grohe Further disassembly step e
e. Unscrew second cap
Grohe Further disassembly step f
f. Remove cap and clean inner and o-ring sides
First squeeze both latches (1) and than pull the frame upwards (2).
Grohe Remove stabilising frame step a
a. Release and pull frame
Grohe Remove stabilising frame step b
b. Remove frame
Separate it to 3 parts while inside the cistern.
a. Turn blue cap CCW (1) and remove it (2) Let inner seal rod drop down into the container. (3)
a. Turn blue cap CCW (1) and…
Grohe Remove discharge valve step b
b. Remove the pneumatic sub-assembly
Grohe Remove discharge valve step c
c. Remove the seal rod
d. This is the pneumatic discharge valve Image shows it assembled, outside the cistern
d. This is the pneumatic discharge valve…
Note: Correct orientation of the Blue cap in image 10.d. should be turned by 180 degrees, as seen in image 10.a.
a. Parts of the pneumatic valve: Cap (1), Pneumatic sub-assembly (2) and Seal rod (3)
a. Parts of the pneumatic valve:…
b. Release 3x snaps holding the pneumatic cap. Pull cap out
b. Release 3x snaps holding the pneumatic…
Grohe Further disassembly step c
c. This image shows the cap removed
Grohe Further disassembly step d
d. Remove inner cylinder, pay attention to its slides
e. Rotating handle of the inner cylinder Make sure handle moves freely
e. Rotating handle of the..
f. This pin moves by small button air push Blow air through the hose to test it moves freely
f. This pin moves by small button…
g. This small cylinder moves by large button air push Blow air through the hose to test it moves freely
g. This small cylinder moves by large…
h. When assembling, pay attention that this latch goes under the snap
h. When assembling,..
To replace the seal, press the 3x snaps, release and pull the outer ring out.
To replace the seal,…
Located at the end of the rod.
If Silicone seal needs to be replaced, this is where you’ll find it
Tip: Clean the cistern container.If you have got that far, it is advised to clean the bottom of the cistern container. Insert your hand in the container and pick any stones, sand etc. found in its bottom. You can turn on water supply and use running water to move and flush any debris found in the container bottom.
Since water goes from the container to the toilet, it is best to take out any large particles by hand to avoid jamming of the toilet water diffuser holes.
Assembling steps:
- Insert the seal rod to the cistern. (seal facing down)
- Insert the pneumatic subassembly to the cistern and insert the rod inside it using its slides.
- Place the Blue cap on top of the rod (6L in front), turn it CW and lock it.
- Place the pneumatic discharge valve inside the center pipe, rotate it CCW until it drops down into place and lock.
- Insert the stabilising frame. Make sure it is locked into its place.
- Insert the float valve while rotating it.
- Connect the float valve to the stabilising frame. Make sure you hear the click when it is locked.
- Connect the water supply hose.
- Install the plate frame.
- Turn on water supply. Turn screw CCW. Make sure it does not leak.
- Connect the 2x air hoses to the actuation plate. Make sure hoses are not bent and its path is clear.
- Install the actuation plate to the frame
- Test each button.
Tip: In order to keep the shiny chrome coating of the actuation plate and buttons for years to come, DON’T use any toilet cleaner or any other aggressive cleaning material. Use only a soft paper towel with some window cleaner that contains Alcohol to clean and disinfect it.
Enjoy, Avi Schneor 
* For Hebrew intro, follow to this link
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Hi, great instruction and appreciate the detail. I followed it and took the parts out for a good clean. The system is still very slow to fill.
Would you advise that I go through the decal process or could there be a part restricting the flow?
Appreciate your help,
Brian
Thank you.
Water supply is regulated by a valve (section 2. and 6. in my post). Try to open it more and if this does not help, disassemble the connection (shut off the house supply or a safety valve that controls this line), clean the connection and the small hose and check if flow to this point is normal.
Good luck