Air accumulating in system. No pressure loss.....

[nomis]

Hello, I'm hoping someone can help...
I have a system boiler (Worcester Bosch 18i - Unvented) in my garage. I am having to bleed top towel rad in house and magnaclean next to boiler daily. Air is getting into the system. I have no loss in pressure. I have removed the lower level rads in house and flushed (some sludge but not too much) I have also run system with X400, flushed and refilled. The air accumulates with hot water and/ or central heating running...

 

[chris watkins]

Some parts of the system are under negative pressure this is allowing air to be drawn in without showing signs of leakage. Not so common with a system boiler because the the pump & expansion vessel are normally installed correctly in relation to each other. Check any Auto Air Vents & tighten down there caps just to ensure it is not entering via them. (you may need a Gas Safe Engineer to check the boiler over)
What is the system piped up in, plastic or copper?

 

[nomis]

Hi Chris, Thanks for you reply. The whole system is copper.

 

[Harvest Fields]

How many radiators do you have? Did you add any inhibitor into the system after the works was completed?

 

[nomis]

I have ten rads. Yes added inhibitor and have used test kit to ensure correct amount

 

[Harvest Fields]

I have ten rads. Yes added inhibitor and have used test kit to ensure correct amount

How old are all the radiators?

 

[nomis]

Mixture of ages. I don't believe the issue is corrosion though as I also get build up of air only when hot water is on...?