Flow of water thru shower head is barely a trickle

when he soldered the connections on these pipes.. he may have partially blocked the flow with solder inside..if its restricted up to 50% then its a hell of a pressure loss..hot water is always lower in pressure anyway..also take the shower head and dunk in a clr solution it may have calcium deposits inside the small plastic orafices in it..

its called a flow switch it is in the pump can b replaced when u turn on it pumps air in valve shuts replacemnt will sort it

Limit message is when the output water set temperature can not be reached, this is normally when the incoming hot water to the shower unit is not sufficiently hot. Service code 20 is something else inside the unit that is faulty, it could be a number of faults. Try reset Power down unit and re-start, it will either say Wait or Priming, after that it should restart, hopefully it will work. If not, you could have a internal fault with: The mixer valve/motor, the flow control valve or motor, the flow sensor. If you have hot water from other taps, then the mixer valve/motor is the most likely fault. If you only have cold water only from the shower head with limit message it could be the Hot solenoid controlled valve is faulty. Good luck as there are no spares available!

low pressure

If you spin the shower head off there should be a metal screen inside. If it is clear, Soak the shower head in CLR for about 4 hours. After 10 years even the best water supply will leave behind a build up that can plug the tiny holes.

I haven't had a lot of experience with Grohe brand but have had twenty eight years as plumber, 22 years as master plumber and the bottom port of every tub or tub/shower valve that I installed used the bottom as main supply port. As far as the instructions from manufacture like I said I have not used that particular brand much,so I really couldn't say. Hope this helps some. Thanks

Try flowing more hot water with your shower. During the summer you end up mixing alot of cold water and very little hot water (because your cold ground water isn't so cold in the summer). When you get close the minimum flow rate of the appliance, it will start to short cycle (fire on and off). Here's some recommended things you can do:

1) Clean the shower head - remove scale deposits and or clogging
2) Widden flow restrictor - most shower heads have a flow restrictor on the back of the showerhead; It consists of a rubber washer with a hole in the center. You can widen the hole using a drill bit.
3) remove the flow restrictor - this should be a last resort

Hot Water Hot to Cold And back. I had that problem for 2 years. I had a very large shower head from the time I installed the tank-less hot water heater and the water temp would change from one extreme to another. Over time my shower head had stopped working as well as it did so I bought a smaller shower head and installed it and amazingly my water temperature quit changing temperature. I now turn my water to what temp I want and it stays there. It's been working correctly for 6 months now ... until yesterday and it quit working completely which is the reason I'm on here. lol

install a shower head diverter, it is a push pull valve that goes on the shower arm before the shower head

the temp, control valve is getting to hot!!! there for only let so much hot water go thru, did you take the inner parts out when soldering this in, if not you might have damaged it, and if so need to replace the cartdrige