.. wrote:


My heating system has microbore downstairs with each radiator
individually fed by down pipes behind the drywall. So there is no
downstairs circuit as such. Upstairs is normal 15 mm.
I have put Sentinel 300 in the system to clean it.
I am about to drain down and put Sentinel 100 in as inhibitor.
There are 10 rads downstairs and to empty the system completely I would
have to empty each down stairs rad individually by the valve cum drain
point which could take some time with trays.
Would it be harmful to just drain the upstairs and leave the Sentinel
300 in the down rads there?

With a bit of ingenuity you can arrange to flush out all the rads without
draining them all