Draining my pressurised heating system

[budest]

Hi all,

Almost finished the re-plumbing of my wet room that I have planned to have tiled in the new year but I have one job left that I'd like to tackle before Santa comes. I need to drain the central heating system and once again require some advice.

I assume the drain-off valve is that in the bottom left of the attached photo? Is it a case of connecting a hose and turning the nub at the end of the pipe? Should I close all radiator valves too?

Thanks as always in advance

 

[oldbuffer]

Following assumes you have the right drain off cock. Connected to copper pipe going into lower "COIL" tapping on cylinder, and not coming direct from cylinder.
1. Connect hose to drain off cock. Use a jubilee clip to make sure it doesn't come off / drip.
2. Make sure hose runs downhill to drain point.
3. Latch all motorised valves in the open position.
4. Turn off boiler, and make sure filling loop is closed.
5. Loosen square headed nut at end of drain cock until water starts to run into hose. If it doesn't run, the washer in the drain cock may be stuck / damaged. If so, find an alternate drain off point (lower on system). Remember to fix drain off cock when system empty.
6. Loosen radiator bleed screws, starting with the highest one in the property, then next lowest and so on.
7. When water stops running, tighten all radiator bleed screws.
8. To refill:
8.1 Open filling loop and fill to pressure of 1.3 bar.
8.2 Bleed all radiators, starting with the highest.
8.3 Bleed coil for hot water cylinder.
8.4 As system fills boiler pressure will drop. Keep topping up to 1.3 bar.
8.5 Add inhibitor. If you have a suitable magnetic filter, this may be used, in which case add via filter at any time after first radiator bleed. Otherwise add through towel rail (if fitted) by removing blanking plug before bleeding. Otherwise find another way of adding (injection, through partly bled radiator etc.)
9. Turn system on and check for leaks. Motorised valves will automatically reset.

 

[budest]

Following assumes you have the right drain off cock. Connected to copper pipe going into lower "COIL" tapping on cylinder, and not coming direct from cylinder.
1. Connect hose to drain off cock. Use a jubilee clip to make sure it doesn't come off / drip.
2. Make sure hose runs downhill to drain point.
3. Latch all motorised valves in the open position.
4. Turn off boiler, and make sure filling loop is closed.
5. Loosen square headed nut at end of drain cock until water starts to run into hose. If it doesn't run, the washer in the drain cock may be stuck / damaged. If so, find an alternate drain off point (lower on system). Remember to fix drain off cock when system empty.
6. Loosen radiator bleed screws, starting with the highest one in the property, then next lowest and so on.
7. When water stops running, tighten all radiator bleed screws.
8. To refill:
8.1 Open filling loop and fill to pressure of 1.3 bar.
8.2 Bleed all radiators, starting with the highest.
8.3 Bleed coil for hot water cylinder.
8.4 As system fills boiler pressure will drop. Keep topping up to 1.3 bar.
8.5 Add inhibitor. If you have a suitable magnetic filter, this may be used, in which case add via filter at any time after first radiator bleed. Otherwise add through towel rail (if fitted) by removing blanking plug before bleeding. Otherwise find another way of adding (injection, through partly bled radiator etc.)
9. Turn system on and check for leaks. Motorised valves will automatically reset.

Thanks for the great tips! Really appreciate your time and effort in trying to assist.

I wanted to drain the system as I am replacing a chrome towel rail with a black one and needed to remove the chrome nut that was used for the previous valve. But I found a workaround that didn't involve me tampering with the heating system, I bought a heat-resistant spray paint and painted the nuts and the white tails.

I will give them another coat before bed and then tomorrow I will replace the valves with black ones and install the rad.

Thanks again though for your help and advice.