Sime 80 C- no hot water + sometimes orange light flashing?

five year old Sime 80 C...have 2 faults(or are they linked)..no hot water at all with heating on or not , if set to water only ,open tap- boiler doesnt fire...why!!...2nd fault...with heating on constant external stat in kitchen set at 16 deg...3 or 4times per week ,boiler will not auto start until boiler temp drops to/below apprx 30 deg and pressure drops on guage with orange led flashing (manual says low press fault)....are they seperate faults??..any ideas