Keep having to bleed the system

[BW2]

I’ve got an unpressurised CH system. About every couple of weeks I’m having to bleed one of the radiators, and I’m wondering/worried where the gas is coming from.

It started about 3 months ago – for no reason – no work has been done on the system for a couple of years. It had inhibitor added then.

The rad is about 60x60cm square, and I have to bleed about half of it each time.

I wondered if the drain cock was leaking, and fresh water was being continually being added to the system, but there’s no water coming out there.

 

[Bahco]

Tie up the ball valve and monitor water level. If water level drops then you have a leak

 

[weareleeds]

Could also be air entrainment from expansion pipe if say cold feed is blocked or possibly hydrogen due to system corrosion

 

[howiel]

Rust could be the cause..

 

[Timmyturtle]

Hydrogen will ignite if you hold a match next to it when you bleed