Noisy water heater in airing cupboard

[answerbanker]

When my water starts heating up the noise from the airing cupboard (like a whooshing noise) is s loud I can hear it in the lounge through the ceiling !! Any ideas what is causing it and how to fix it please ??
Thanks

[maclarencat]

Has it just started doing it? If it has always done it ,it is usually just the gas igniting

[bushbaby_de]

You have my sympathy, my immersion heater sounds like a sodding great kettle and its just behind the wall where my bed is :(

[answerbanker]

No - its been doing it for a long time. It starts not long ater the timer comes on (as its heating up presumably) and it lasts for about half hour !!