Go round the house and make yourself a radiator checklist of all the radiators in the house, which you can mark off against each time you open or close the valves on a radiator. Forgetting to close the bleed valve on a radiator before filling is a messy mistake.
When I did a similar repair, my process was as follows (2 people is ideal for this, if you do it alone it requires a lot of running about). I'm sure there are many different methods for doing this, but this one worked for me.
1. Isolate the boiler.
2. Find the lowest radiator drain point and put a container under it.
3. Open the drain (some fluid will come out but not much). Keep in mind this may contain inhibitor chemicals and other nasty deposits.
4. Start at the top of the house, fully open the bleed valve and the TRV/radiator valves on each radiator in turn and leave it open. Then work your way around all the radiators back to the drain radiator.
5. You'll probably need to swap/empty the container several times.
6. Once all the bleed valves are open and no more liquid comes out, close the drain valve.
7. Do your repair.
8. Go around and close ALL the bleed valves and TRV/radiator valves (use the checklist!)
9. The next bit is easiest with 2 people. Have one person stay with the boiler and operate the filling loop - their goal is to keep the pressure just above 1 bar at all times (or whatever is suitable for your system when cold).
10. The other person then goes around, starting with the radiator closest to the boiler, opening the TRV/radiator valves to full, then opening the bleed valve and leaving it open until fluid comes out, then closing. When it's full, move onto the next one.
11. Each time you fill a radiator, the pressure in the system will drop. If you have an accomplice they should be using the filling loop constantly to keep the pressure up. If you're on your own, go back to the boiler after each radiator and get the pressure back up - or you can just leave the loop open while you run around all the radiators but keep checking on it as it's easy to over-pressurise that way.
12. Once you've got to the last radiator - loop back to the first, and bleed them all again.
13. Keep doing this until you're satisfied that they are all full.
14. Close the filling loop, verify the system pressure is correct for your system.
15. Turn the boiler on. Activate the central heating.
16. The pump will start and you'll likely hear a lot of noise and bubbles as the pump moves air around the system. If the pressure drops sharply, turn the boiler off and repeat steps 10 onwards again, get the system back up to pressure.
17. With the CH running, go around and bleed all the radiators again. Allow the system to warm up.
18. If any radiator is cold at the bottom, then there is likely an airlock. You can often resolve these by turning off/on the radiators around it, putting more pressure on the air lock. This wasn't an exact science for me, but after about 20 mins of trial and error, I resolved the 2 airlocks I got. Keep in mind after you resolve an airlock, that air is still in the system and will need to be bled off and the system topped up.
When I did a similar repair, my process was as follows (2 people is ideal for this, if you do it alone it requires a lot of running about). I'm sure there are many different methods for doing this, but this one worked for me.
1. Isolate the boiler.
2. Find the lowest radiator drain point and put a container under it.
3. Open the drain (some fluid will come out but not much). Keep in mind this may contain inhibitor chemicals and other nasty deposits.
4. Start at the top of the house, fully open the bleed valve and the TRV/radiator valves on each radiator in turn and leave it open. Then work your way around all the radiators back to the drain radiator.
5. You'll probably need to swap/empty the container several times.
6. Once all the bleed valves are open and no more liquid comes out, close the drain valve.
7. Do your repair.
8. Go around and close ALL the bleed valves and TRV/radiator valves (use the checklist!)
9. The next bit is easiest with 2 people. Have one person stay with the boiler and operate the filling loop - their goal is to keep the pressure just above 1 bar at all times (or whatever is suitable for your system when cold).
10. The other person then goes around, starting with the radiator closest to the boiler, opening the TRV/radiator valves to full, then opening the bleed valve and leaving it open until fluid comes out, then closing. When it's full, move onto the next one.
11. Each time you fill a radiator, the pressure in the system will drop. If you have an accomplice they should be using the filling loop constantly to keep the pressure up. If you're on your own, go back to the boiler after each radiator and get the pressure back up - or you can just leave the loop open while you run around all the radiators but keep checking on it as it's easy to over-pressurise that way.
12. Once you've got to the last radiator - loop back to the first, and bleed them all again.
13. Keep doing this until you're satisfied that they are all full.
14. Close the filling loop, verify the system pressure is correct for your system.
15. Turn the boiler on. Activate the central heating.
16. The pump will start and you'll likely hear a lot of noise and bubbles as the pump moves air around the system. If the pressure drops sharply, turn the boiler off and repeat steps 10 onwards again, get the system back up to pressure.
17. With the CH running, go around and bleed all the radiators again. Allow the system to warm up.
18. If any radiator is cold at the bottom, then there is likely an airlock. You can often resolve these by turning off/on the radiators around it, putting more pressure on the air lock. This wasn't an exact science for me, but after about 20 mins of trial and error, I resolved the 2 airlocks I got. Keep in mind after you resolve an airlock, that air is still in the system and will need to be bled off and the system topped up.
