Heatrae Sadia Multipoint 10 Overheating water

[msw109]

Water from the tap that this feeds is scalding hot. I've checked the Aquasystem 2 litre expansion vessel that's associated with it and there's no pressure in it. The safety valves seem ok. Would this lack of pressure in the expansion vessel cause the water to become extremely hot?

 

[Dotty]

No. You need to get a competent person to look at it for you.