Sucking in air

[seco services]

Hi Guys, I appreciate the help.
The 15mm pipe on the left starts at the header tank, goes down to the airing cupboard where it goes into a 22mm T. One continues down (presumably to the boiler), the other branch to the bottom of the cylinder coil.

The 22mm pipe comming out the top of the seperator just goes straight to the header tank, no other connection.

Hope this helps.

thats not right then. sounds like it's just teed into the boiler return.
i'd move it. and make it a combined feed/vent.

 

[wadihalfa]

I just did the cup of water trick in the loft and it definately sucked.
This system has been running for at least 13 years to my knowledge and I've never had to call a plumber, except to change the cylinder.
Is this just a badly designed system?
What would be the best way to recify the problem?
Will it make any difference once I fire up the CH system?

I've added another photo to hopefully make things clearer. View media item 26211 View media item 26212

 

[45yearsagasman]

You almost certainly have a blocked cold feed(where that 15mm connects to the common return.The blockage is causing excessive suction down the open vent.You can clear the blockage at the cold feed connection and that should go some way to stop air,or better still connect the cold feed to a tee between the air sep and pump,keeping the connection as close as you can to the air sep.Just looked at your pic and there is no room to connect between sep and pump so tee just above the sep and connect there.A better way(providing your boiler has an oveheat) is to connect the 22mm below the water line and to cut off the 15mm.Called combined feed and vent.

 

[rojaca]

i'd say its just as likely to be the orientation of the cold feed in relation to the expansion pipeshould ideally be between the separator and the pump.

Apologies if i've duplicated anyones posts-its late and had a long day.