How to balance water pressure

[thesmoothound]

Hi.
I recently had some taps replaced in bathroom. The plumber couldn't access the iso value to shut off hot and cold feed to the taps so had to shut off cold mains. Since then, the water system has not been right. For example, when in the shower (electric) and someone turns on another tap in the house, the pressure of shower drops and then water temperature soars to boiling. The plumber came back and drain system down again. Seemed OK for a couple of days but then returned.
Any advice on how to rebalance would be helpful. Thank you.

 

[thesmoothound]

I meant to say that I have a combi boiler. Thanks

 

[Johntheo5]

First check that the mains stopcock has been reopened fully.
IF the shower is supplied from the combi then it willl normally have a thermostatic elememt to mix the hot and cold water. If its a electric shower then its only supplied with cold mains water, which is it?.

 

[thesmoothound]

Thank you. The shower is electric.

 

[Johntheo5]

Thank you. The shower is electric.

What make/model shower?.
Some scale/deposits etc may have been dislodged when turning the mains on/off and may have blocked the shower inlet filter, needs the cover removed from the shower and with mains and power isolated to remove and clean the filter. You should get a flowrate of ~ 8LPM with the temperature control turned to fully cold.

 

[thesmoothound]

Thank you for your help.