All you have to do is add the flushing agent to the existing water in the system,
then run the heating for a minimum of 2hrs but i'd leave it running for a couple of days.
The flushing agent breaks down the sludge so that it circulates around the system and is not in a sedimentary state!
After it has been in the system for a couple of days drain the system and refill with fresh water and inhibitor.
If the water was very black when you drained down then you could just fill the system with water only,
run for a few hours then drain down then refill with water and inhibitor.
Originally Posted by Hightower
When flushing the system, do I have to remove all the radiators and force flush them with a hose? Or just empty the system.
if you have an open system with a tank then stop of the valve and drain down enough water to empty the tank,
add the flushing agent to the empty tank then unstop the valve to allow the tank/system to refill.
if you have a closed system,(no tank) then drain down the system a little then add the flushing agent to an upstairs rad.
then refill and vent rads