Grohetherm Wireless! Part No. 36 022 '20 Service' error

Discussion in 'Plumbers' Talk' started by Pistol Pete, May 29, 2012.

  1. Pistol Pete

    Pistol Pete New Member


    I have just moved into a new house (not a new build, but new to me!) and it has the above shower system installed.

    The previous occupants clearly weren't using it as the batteries in the control unit were dead.

    Having put new batteries in, I switched it on and it ran for a few seconds before cutting off displaying '20 Service' on the control.

    Does anyone know what this service code refers to so I can try to work out what the problem is? The water flow seems fine for the 10 seconds or so that it runs for each time I reset.

    The unit is fitted in the airing cupboard next to the water cylinder with the cold feed being above in the loft.

    All the pipes seem to be connected and the hot feed valve is in the 'on' postion but there doesn't seem to be a valve in the airing cupboard for the cold so don't know about this and I'm no plumber so short of unscrewing the pipe and seeing if water gushes everywhere I'm not sure how to check the cold feed!

    Does anyone have any experience with this system who can help me please?



    EDIT: I have gone in the loft and found the cold feed direct off the water tank. I have switched the shower on and it is definitely taking cold water so both hot and cold feeds seem to be working. I have found the specificinstructions for the model I have (attached) and they say this about the service code I am getting:

    "The pump cannot be allowed to run dry and the system will stop this from happening for longer than 10 seconds by switching off the system and displaying Service 20"

    it then goes on to suggest some fixes - I have tried sucking on the shower hose to help with priming with no success, but the other options are beyond my amateur capabilities!

    Attached Files:

  2. G Brown

    G Brown New Member

    There is/has been air in the system, it needs bleeding thru.
  3. Pistol Pete

    Pistol Pete New Member

    how do i bleed it through?
  4. kinger305

    kinger305 New Member

    Hi, I have the exact same problem with an identical unit, I have been searching for a solution for more than a year, I'm just about ready to give up on it even though it was an expensive shower to have installed its useless as it is, if you come up with a fix please post it.
  5. bathstyle

    bathstyle Active Member

    Turn the fused switch supplying the shower off then on again.

    When the unit is turned on again 'priming' will be displayed on the controller.

    The second the pump kicks in, suck the shower hose as though you were trying to suck a golf ball through a hosepipe.

    Good luck.

    *if you don't manage to suck the water in to prime the pump then pass the hose over to your Wife as she might have more luck.
    Last edited: Aug 30, 2014
  6. tom.plum

    tom.plum Screwfix Select

    hello b'style, welcome back ;)
  7. bathstyle

    bathstyle Active Member

    Hi Tom.

    The last time I was on was 2012 and before that it was 2010!

    Time Flies when you're having fun!
  8. rramic

    rramic New Member

    Hi all,
    I've just had some problems with my Grohtherm similar to Pistol Pete. If you open the pump box you will reveal the electronics. There is a small button just next to the only green led you will see. I pressed it for 5 seconds and then released. I think that must have reset the pump as well as the communication with the remote control. It appeared to have fixed the 'cut off' and the service 20 notice.

    Also, I have a leak on the pump.. I know there are no service parts however is anyone selling an old for spares ??

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