Pressurised combi-boiler central heating.

Have to re-attach a rad downstairs that’s been off while I did a floor (in my own house!! 😯 ). The radiator is empty.

What would be the best sequence for re-filling/bleeding/pressurising etc to avoid airlocks?

Dunno, I just drained my entire system, removed and re-fitted all the radiators, opened the filling valves and wandered round the radiators with the bleed key starting at the point furthest from the boiler.

Might not be right, but it worked (as far as I can tell, and I had to drain/fill it 3x to run the cleaner through, flush it out, and refill with inhibitor).

Combi is upstairs btw.

Dunno but Plumber Parts will entertain and inform along the way.

https://www.youtube.com/user/plumberparts

He’s my plumbing DIY go-to man and he has vids for all this kind of stuff.

If you left the valves fitted to the tails then just rehang it on the wall, screw the valves back onto the rad and open them slowly.
One pressurised, bleed and top up system accordingly.
Should take about 30mins tops.

Not an answer to your problem but, why did you need to remove the rad to do your floor?
Edit: And what Hammyuk said.

probably in the way and easier to fit the beautiful handmade [ no doubt stolen from a customer* ] wooden flooring over the pipe than cut them is my guess

Depends on the boler mine auto bleeds so you can just plumb it in and switch on. Top up with water as required

A bleed may well help and tbh i would open the bleed port as I filled the radiator – or it wont really fill easily and will trap air.

* perks of the job innit 😉

Not an answer to your problem but, why did you need to remove the rad to do your floor?

It’s a fair question. It was removed for redecoration – needed to strip a load of lining paper off the wall. Leaving it off was because the skirting was being replaced and I wanted to be able to do it in one piece rather than having to join it behind pipes etc.

Thing is, I’m thinking…if rad is downstairs, and I open the re-pressurisation valve on the boiler to start re-filling the system, then open valves and bleed on the rad, it should hopefully pressurise without introducing airlocks upstairs shouldn’t it? As soon as water comes out from bleed, run upstairs and close re-pressurisation valve on boiler and I’m good. Bleed rest of rads to check. Re-pressure and I’m done. What could go wrong?

Yes.
I would make sure plenty of pressure in system ~2 bar.
Then refit rad , open flow valve with bleed valve open , fill rad.
When the pressure drops(depends how big rad is ,you’ll hear it hiss), stop, close flow valve and run up stairs and re pressurize and repeat. When there is only water coming out I open the return valve on the rad.
No air locks here.
What could go wrong? – Don’t cross thread the valve fittings for one… 😉

If it were me (i’m not a plumber but put my system in), i’d drain the whole system. They can do with a wash through every now and then with some new inhibitor in, it well help get the much out that builds up (even with inhibitor) which will make the boiler feel happy inside and less creaks and groans from the pipework.

As others have said, i pressurise the system to 2-2.5bar, close off then go round with a key letting th air out until the pressure drops. Re-pressurise, then start again. I don’t think you’d need to worry about over pressure as there should be a release valve built in which will dump the excess outside, though it could highlight some dodgy fittings!

fit rad , open one side of the rad and the air bleed – fill the radiator. then open the other side of the rad- air is pushed out the bleed port instead of pushed into the system.

also junkyard – how does your self bleeding boiler get the air out of the top of radiators ?

i wouldnt be stickign 2.5 bar into my boiler – thats the PRV release pressure and those can be a royal CHUNT to seal again once activated

Thanks all. I have a few plumber mates who I might book in to do a drain, flush and refill while we’re away for a week at the end of the month but for now, I just need this rad back on. Now that it’s cooled down a bit the room it’s in has become a vacuum sucking the heat out of the hallway.