Central Heating Drain Down

[Quattro]

I have a need to remove 2 or 3 rads and a towel rail and would like to drain down the system. Could someone give me some advice as to how I should go about this please.

The system is unvented with a Potterton boiler.

 

[Softus]

1. Turn off boiler and, if controlled separately, the pump.
2. Attach a hose to a drain-off cock.
3. Ensure that the filling loop is disconnected.
4. Open the drain-off cock.

 

[Steady]

5.vent rads