Using one shower makes second shower run/make noise

[WaterTight]

Sent a video from a friend of mine who is a plumber bit new to game. Not a job of mine or one I've visited so limited info. But was sent a video. When a shower is used a second shower in another bathroom in the house runs (more than a dribble, quite a bit comes out) and makes high pitch airy/whining noise. It's a combi.

Something like reduction in standing pressure causing something? Built in valve and fixed head.

Never had this myself so not sure what to tell her to do/check

Thanks

 

[king of pipes]

Are they using both at the same time ?? if so it is not possible, the litres per minute and pressure provided from the incoming supply will only be enough for one shower at a time demand will strip the supply and cause banging of pipework and temperature issues . Kop

 

[WaterTight]

No, it's when one is used the other one drips and screeches.

 

[Shower Engineer]

No, it's when one is used the other one drips and screeches.

Is the one that drips a Bristan shower?

 

[WaterTight]

Here is a video. Shower has no name written on it and customer doesn't know what it is. This is what it does when the other shower in another room is used.

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And this is what it looks like