Can't identify the souce of hissing sound

[Glyn1959]

Hi, there is a hissing sound coming from where the washing machine and tumble dryer are positioned in our utility room. The gas supply comes in from the outside in this area but there is no smell. The only other pipes are single hot and cold water pipes feeding to/from the kitchen and through to/from the combi boiler and downstairs bathroom. There are no signs of a water leak.
The noise continues when the boiler is turned off, the water is turned off at the mains and the electricity is turned off at the mains and the washing machine cold water inlet hose is disconnected! Its a fairly quiet but consistent hiss.
Any ideas folks?

 

[oilhead]

ith everything turned off, is there any movement in the meter reading?

 

[picasso]

If you have a stopcock/water meter at the edge of your property try turning it off there, its probably a leak before your internal stopcock.

 

[KenGMac]

Glyn1959, good evening.

Most certainly agree with picasso, above.

Some very small leaks can and do make one hell of a noise in pipework. Try to place your ear on to all the pipes in the property, the further away from the inlet it goes quieter then an external leak is very much on the cards?

Ken.

 

[JimCrow]

Hi, there is a hissing sound coming from where the washing machine and tumble dryer are positioned in our utility room. The gas supply comes in from the outside in this area but there is no smell. The only other pipes are single hot and cold water pipes feeding to/from the kitchen and through to/from the combi boiler and downstairs bathroom. There are no signs of a water leak.
The noise continues when the boiler is turned off, the water is turned off at the mains and the electricity is turned off at the mains and the washing machine cold water inlet hose is disconnected! Its a fairly quiet but consistent hiss.
Any ideas folks?

Do you use LPG.

 

[Glyn1959]

Thanks for the replies to date.
I don't have a water meter and don't use LPG. The water main comes from the front of the house with the stopcock in the kitchen (standard) but the hissing is coming from the utility room beyond the kitchen. I could get the water shut off outside but becasue of where the hissing is I don't believe there is a leak between the outside and inside stopcock. Confused?? I certainly am!

 

[big-all]

through the wall from next door perhaps ??

 

[Glyn1959]

It's an outside wall and no hissing noticeable outside :~

 

[big-all]

other thoughs
something with a speaker like a radio off channel or a toy where the damp can cause hiss
have you tried all cupboards and other rooms around below and above

 

[Glyn1959]

Source Identified. Water company came around and asked if they could check in and around the property as they believed there was a leak. They found it outside the wall the hissing was comiing from. This means the water main doesnt take a direct route from the outside stopcock to the inside stopcock which i tought it did. The outside is gravel and the leak is right next to a gully (also covered in gravel) hence no water build up! Hopefully they are back today to fix! Thanks for the suggestions. Great forum!