Draining down combination boiler/ central heating system

[ace high]

Could some explain procedure for draining down system with combi boiler

I have tried once before but the water flows very slowly and seems to take forever. In addition how do I know when all the water is out as there was a trickle for 1 hour or so and not sure if all water was out.

do I have to make pump operate for short time if so how?

PS about to add inhibitor Sentinel or fernox best?

Many Thanks for any replies

 

[compheat]

You need to isolate the boiler by turning off at switched fused spur or plug.
open drain off valve and open bleed nipple's on all rads this will drain all water. To put inhibitor into system turn off drain valve remove 1/2" blanking plug from any rad and using a tundish/funnel put inhibitor in. Refit blank, turn off all bleed nipples repressurise to 1.5 bar vent all rads recheck pressure and that should be ok But if i've missed anything i'm sure someone will let us know