Hot water overflow - Sealed boiler system?

[paulfoel]

Help. Boiler is making a funny noise and hot water seems to be leaking out of some sort of overflow.

Its a sealed system I think - one big boiler and two small bits.

Also, any hot water is not kept hot for long. Is it leaking away?

Is the pressure too high or something? I can see a clock display but thats only just under 1 bar.

Any ideas?

[David]

Do you have an unvented cylinder?

[paulfoel]

I think its unvented.