Sime boiler, water won't run hot new diverter not solved the problem hot water or heating on or off, cuts out

Question

Please help, as the central heating is cutting out and the pressure guage seems to get high

Answer 1

Sounds like you need the Expansion Vessel recharged. This is a big red vessel in the boiler that absorbs expansion of the water upon heating.If the charge the other side of it's diaphragm is lost, the system expansion is not absorbed & the pressure goes up too high & the pressure relief valve blows at 3bar, sending water outside via a copper pipe & the overheat safety stat turns the boiler off. The good news is vessel can be recharged in 10 mins by a competent heating engineer using a car foot pump

Answer 2

You need a new water heater, this one sounds like it has a leak and lots of sediment in the bottom, constricting water flow.