Hi guys. 1st time post so pls be gentle. I recently went to a oso 20 rd unvented cylinder. No hot water but good flow to all outlets. Checked out all preliminary electrics and all ok to primary element (none to Eco7 but apparently this does work so hot water mornings only). Cut out hadn't popped. Good pressure thru-out What would be the most likely cause, stat failure or p & t assembly, or could it be the element itself . . . or am i barking up the wrong tree completely. Cheers