The Murrayburn contract involved a complete system drain down and cutting in of ball valves for future isolation of phased works. We then fitted a new 2 pipe heating mains in the corridors along with anchors and expasion bellows. Once complete it was a case of isolating the phase to be worked on ( 2 classrooms per phase ), drain down, strip out the existing pipe system, pipe the existing cast radiators, connect to the new 2 pipe mains, testing and make the phase live. When a phase was finished I'd then prefabricate the pipework sizes ready for the next 2 classrooms. There were 15 radiators to each phase and the work took about 1 week per phase from start to finish.