Hiss in pipes

[lvegas2009]

I can hear a constant hiss in some of the, I think, central heating pipes. The noise is present when the boiler is running the heating cycle or not. Does anyone have a suggestion what might be the cause. This has been going on for several days.

The pipes run through a hallway cupboard to a bedroom above and onto the bathroom. Noise seems most noticeable inside the bedroom radiator and the bathroom rad (not quite so loud, but a more modern rad). Cannot here the hiss so clearly in other upstairs radiators.

The water mains runs in the same cupboard, and the pipes are near / touching the heating ones. There is no sign of a leak on this, or on the downstairs ceiling.

Is is possible that "something" is moving water round heating pipees, even when heating not running? (perhaps a pump)

Alternatively, if the leak is on the mains, does anyone have a trickf for finding the likely source/location?

 

[bspareltd]

Open vented drawing air in .

 

[lvegas2009]

Please can you explain, open vented?

I have a sealed system, I think, combi boiler (Worcester 30cdi)

 

[bspareltd]

if it is a combi then it is a sealed system , you need to look if pipes are not rubbing against each other

 

[lvegas2009]

Pipes do touch each other, but have so for years

 

[hammers4spanner]

havnt lost a pet snake have you??

take your meter reading before bed then first thing before anyone uses water in the morn if different reading you have a leak

 

[stoker122]

Turn off the mains water stopcock and see if the noise stops 🙂