heating

[ashley dias]

how do you bleed radiators without the key for a combi boiler?

[ianess]

Strange question..........the type of boiler makes no difference when it comes to bleeding air out of radiators......you still need a key [available almost anywhere including Woolies] to open the tap and let the air out.

The main query is to ask how air is getting into the system in the first place.  A combi system is pressurised so I would suspect that there is a leak somewhere......it may be visible but you might have to call in a plumber/ heating engineer.

Good luck.