Could my grohe thermostatic shower be letting cold water into my system? Some other taps run cool but the shower is running OK temperature

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!

Hi, its probably just the filter to the cold supply needs cleaning; these can get clogged from time to time. Turn your water off, remove unit, unscrew the water pipes which should be the silver flexi type and washout the mesh filters.
Hope this has helped.

The thermostatic mixing spool cartridge may be worn out. The low water pressure may indicate sediment in the cartridge as well. This can be easily removed by hand tools

hi capacity of tank ? temp set low demand to much

from a plumber all hot and cold connections on all major showers are hot on the left and cold on the right just like the taps on your sink or washbowl

Hi,

If the hot and cold are fitted the wrong way round then the thermostat on the shower unit cannot operate properly!

Most thermostatic mixer showers have a 'bi-metallic' thermostat, if you supply the hot to the cold and vice versa IT WILL NOT WORK.

It is like wearing the left shoe on the right foot and the right on the left! It doesn't work.

Re-install the hot and cold to the correct supply, and this will sort it.

I hope this helps.

you need to change the cartridge, it is a temp control and is going bad so it keeps you from burning yourself it is like a mixing valve and is givng more cold water, that way you don;t get burned,,

This is what you should have... Grohe Grohmix Thermostat Valve & Trim - 34436

Paraffin cartridge

Lever volume control

Grip ring temperature control

1/2" NPT female connections

Service stops

Includes rough-in valve and trim

Integrated temperature and volume control

Requires Twin Ell (03 671) for shower/tub combinations with diverter spout Note:

Requires Twin Ell (03 671) for shower/tub combinations with diverter spout

Grohe Grohmix Thermostat Valve & Trim - 34436

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

mixing valve must be replaced