New shower not mixing properly

[SunnyUpNorth]

We had a new Grohe shower installed recently. It has an overhead shower and a separate hand shower.

The overhead shower is working absolutely fine, but when I switch it to the hand shower it doesn't mix properly.

It's hard to explain but it's like the hot and cold aren't mixing properly, I can feel very hot water and cold water coming out at the same time. There is some kind of pump in it as it sort of pulses out. Not sure if that's relevant.

We just had the whole bathroom refitted and are having a second bathroom done now, so the fitter is still here but he hasn't come across this before. So checking here for ideas.

I purposely bought this shower so that the kids could use the hand shower at a lower height but they can't use it at the moment due to this issue.

Any ideas gratefully received!

[PigletJohn]

have you got a hot water cylinder? What colour?

[SunnyUpNorth]

Hi pigletjohn, we have a megaflow. Could it be to do with that?

[PigletJohn]

maybe not. I was thinking the cold and hot might be at different pressures, but in your case they should not be.

Just guessing now.

I wonder if it might be a thermostatic control, for example fitted the wrong way round. Try turning the tap to fully hot or fully cold (there may be a temperature limit button)

You can try turning on the basin taps to see if it makes any difference. you can try holding the hand jet higher or lower. The handheld head will unscrew from its hose, see if that makes a difference as flow will be less restricted.

There should not be a pump, except in very unusual conditions.

Also try phoning the makers, they may have experience of this.

[Boulshired]

I have a similar if not the same shower but a different boiler so I do not know if this is relevant. I find each attachment has a different favourable pressure opening. My larger head is better somewhere between eco mode and full power and the smaller head doesn't mix well above eco mode.