As I understand it, a HIU is what converts the heating/hot water in a communal system (apartment block) for use in each individual flat.
Our current one is 10 years old and has just broken down, and I have been advised by the engineer (from a big company that services a lot of the flats on the development) that it is apparently not economical to repair.
They have quoted almost £4K to replace (with a brand called Rhico) including labour and VAT. I am shocked at the price.
Has anyone got any experience of this type of system? I've had a google around and I think it's quite specialist, so most plumbers/heating engineers won't be interested. It must be quite a common problem though as a lot of people live in aprtment blocks with communal systems.