I'm not confident my central heating was commisioned properly - there's no inhibitor in the system but rather than just add some sentinel x100 i thought i'd put x400 (sludge remover) through first. If i read the instructions right this will then need draining out and refill with fresh then add x100. Combi boiler with normal rads upstairs, one has a drainoff so ok with that part but downstairs is polypipe underfloor heating with the drainoff on the manifold above the pipework. Can anybody with experience of this system tell me how to drain down after the x400 has been added.
Cheers
Lee.
Cheers
Lee.