I'm about to replace my CH header tank due to the old one not having a proper lid (and thus full of green slime), I also need to flush the CH prior to installing a boiler. The rads all get hot, but last time I took a rad off and manually flushed it there was plenty of gunk in it, so it needs a good enema.
Since I'm re-working the pipework to the header tank it struck me I could tee off before the tank, tee back on to the CH feed from the header tank (therefore creating a tank bypass pipe), stick a couple of ball valves in place - one to allow water to flow down the bypass and one to prevent water flowing up the feed into the bottom of the header tank - put a check valve in line and thus have the ability to direct mains pressure water through the system.
Any reason why I should *not* do this?
Also, should I remove/bypass/turn off the valves to the pump when flushing with mains pressure water?