Annoying sound

This morning I woke up and heard a highly pinched beeping sound from our Boiler. I didn't understand, it never happened before. Now, I am waiting for my hubby to wake up and solve the problem. The noise is quite annoying at the moment :(( I tried not to listen but I can't. Waiting for my hubby to wake up, I play at Café World in Facebook and did some browsing through the emi shielding site.