whistling coming from back boiler

[mik118811]

hi all. just recently my back boiler has started whistling when the central heating is on. the whistling seems to be coming from the out pipe from the boiler. is this a problem or is there anything I can do to stop it?
also a radiator downstairs quite a distance from the boiler seems to keep getting air in it which stops it from getting hot properly, I have to bleed the air out every few days. what could be causing this?

 

[djboyd]

What type of back boiler - is it a coal fire? when you say central heating on, what do you mean?

 

[mik118811]

What type of back boiler - is it a coal fire? when you say central heating on, what do you mean?

it is a gas boiler. when the thermostat clicks on and the water for the radiators is being heated it whistles

 

[Flanners]

Gas and air mixture needs adjusting,

 

[Flanners]

or gas valve sticking.

 

[mik118811]

if the gas and air mixture is wrong wouldnt this have happened sooner as it has only just begun? is this something that should be looked at straight away. and have noticed today it happens when the boiler is heating water not when the water is just being pumped round the system.

 

[GrahamM]

A blockage in heat exchanger can sometimes cause a whistleing as water forced through.