Banging pipes and constant bleeding of radiators

[Edmo]

I find that I have to constantly bleed 3 of my radiators, 2 are connected i.e. one is on the ground floor toilet and one is directly above it in the bathroom. if the temperature goes above 24 the pipes bang and its driving me insane. The house is only 2 years old it was re-built by a local builder. We have a combi boiler , the thermostat says honeywell if that helps at all. the boiler in the loft, thus no airing cupboard. If I turn off the 2 radiators that are 'connected ' and turn the heating down then the banging is not as bad. Please help if you can

 

[twgas]

is your system pressure ok after all this bleeding?

 

[Edmo]

Thanks for the reply Mick,

I have no idea how to check the pressure, if you tell me how I will do it tonight, a bit more information on the boiler its a green star CDI Bosch group and a Worcester condensing boiler, if this helps??

We have 12 radiators and the main one in the hall is always hotter than all the others. I have read some other poor guys fault that sounded like mine and the air in the 2 radiators that need daily bleeding has an awful smell to it as well. When I bleed these radiators , when all the air is expelled and water starts to flow it 'bubbles' and 'spits' and the water looks airiated , I have kept going until the water ran clear, however the next day it is the same again.

on a lighter note the banging does have a calypso theme