Pressurised Heating System Not Draining Completely

[king of pipes]

You really are over complicating things use a wet vac isolate the valves crack a valve tail on the rad and just suck the water out job done, empty the water out then you can do the same on the pipework and any other rads connected . cheers kop

 

[ShaunCorbs]

Are you sure the port valves are open ?

 

[Chalked]

Are you sure the port valves are open ?

Yes Shaun. I'm still on here.

 

[ShaunCorbs]

Yes Shaun. I'm still on here.

 

[Technomorph]

Kop, I take your point. I've since just drained the individual radiators in situ and done the work I needed to do. Being my 0wn home I still want to understand why the system did not drain completely. If I need to do further work in future or want to flush the system in it's entirety, I don't want to faff about.

Looking in the airing cupboard again it seems that the returns from all three zones come back to the airing cupboard and join with the hot water on a what appears to be a common return. I've attached an image. It's not that clear, but behind each zone valve, you can just about see a what appears to be a return. Is this normal?

 

[Best]

Going to be fun trying to replace any of those motorised valve bodies in the future

 

[king of pipes]

Thats normal bud from the picture you posted its not the best install all thats needed is a few rad valves swaping for ones incorporating a drain off, but your pretty much there on understanding how it all works. Cheers kop