Firstly for information I am not a “Gas Professional” but a Chartered Electrical Engineer now on the (unpaid) management committee of a block of flats with two elderly U-ducts. We have been working with our managing agents to sort out problems partly due to ducts working poorly with modern...
Just a warning. There is a shaft of new laws and requirements regarding U-ducts and SE-ducts, requiring regular inspection etc. etc., which are causing confusion to many.
In our block we are even considering closing the duct, and forcing all residents top install new boilers with individual...