Lack of hot water for bath

[Jamesbelton5]

A mains feed HW cylinder which used White Meter electric and also has boost function to seperate element. One element is at the foot of the cylinder..the other half way up. The outlet steps down from 22mm to 15mm very quickly after tank?

When a bath is run the water is v.hot but runs to cold with only 1/3 of water required...even with boost funtion used before hand.

Any ideas

 

[kevplumb]

bottom element is kaput

 

[Jamesbelton5]

bottom element is kaput

That had been a thought...but how can that be checked?