Central Heating Whistling following fitting of new radiator

[smithbob1uk]

As part of a bathroom refurbishment, our installers fitted a new radiator. Since then we have noticed significant whistling in our central heating system (not on start up of the system). I have bled the radiators (air was in one radiator only but no further air released in subsequent bleeding) but the whistling continues. Before the new radiator we had no noise in our central heating system. The system was was extensively refitted 6 years ago, including a new potterton suprema boiler.

Any advice appreciated on what could be wrong and what to do next.

Many thanks

 

[Gas2Air]

Turn down lockshield a few turns.

 

[smithbob1uk]

Thank you for the reply and good to know for the future. I have examined the situation further and actually I think the issue is with the water system now following the bathroom refit and not the radiator. Occasionally if using the water supply - a loud whistling sound appears - it may be in the airing cupboard where the hotwater tank and lots of other pipes etc reside, it may be because of the water tank in the loft. I have not got close enough to it yet. I think it is the water supply because if I run a cold tap downstairs which is I think of the main water supply then the noise stops after a minute or so. Sounds like air in the system needing to escape