Header tank feed - on flow or return?

[Spedley]

I'm trying to confirm where the feed from the header tank should be. It seems unanimous that the 'escape pipe' for air should be close to the output from the boiler. It is about 50/50 whether the cold feed/expansion goes just after this and before the pump or somewhere on the return, i.e. just before the boiler.

Here are two examples from the web of what I mean ...

 

[cross thread]

your first diagram is the modern close coupled meathod and most would now use this for a vented system

 

[Spedley]

Thanks, I had a feeling one was the old style of doing things.