aris wrote:

I've got a closed central heating system with a combi boiler. I added
some fernox restorer last week and would like to make sure it is all
flushed out.

There are two valves which I used to drain the system down with - but
gravity doesn't always do its job fully when draining it down by
opening the valves on their own.

I thought that if I open both of the draining valves, and then opened
up the tap which I use to top up the closed system with water, would
that effectively flush out the whole closed system.

Am I being naiive? :-)

If not, what would you all suggest as the best method of fully
draining the system?

This method can work very well if the mains is up to the job.
Make sure the water goes the long way round through the rads (open just
one at a time) and not the short cut straight to the drain!

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html