On 19/12/2015 19:20, DerbyBorn wrote:
I have a couple of sluggish feeds to a couple of radiators. Chemical
cleaners and DIY direct flushing from the mains has not helped. I wish I
could achieve something like the suck - blow effect that a sink plunger
gives to a drain blockage.

Any idea how I could do this on my microbore - perhaps by connecting
something to the top bung of the radiator with just the relevant valve
open?

I've used cable (like inner cable for bike brakes) with a deliberately
frayed end to clear a blocked microbore feed to a radiator in a
neighbours house.
Slackened off the olives. One hardly leaked. Disconnected and shoved
cable down. Had estimated distance to manifold. Worked cable in pipe and
removed. Used old towels to soak up gunge until it ran clear(er)
Reconnected olive and relaxed. Worked for years!
With my similar system, when it gets first use in Autumn. I check all
the radiators, and if one seems poor, I then turn off all the others for
a while. Has worked for 30 years!

Jim