"dbroms" wrote in message
...

We have just had a new worcester bosch system boiler fitted to a fully
pumped system.

System boilers do not have header tanks.

In the night we heard lots of noise from all the pipework and
the radiators so i went in the loft today to check something and found the
header tank which tops up the system has quite hot water in it !!

is this normal? i suspect not

what could this be caused by?

apart from the noise which only seems to happen at night, everything seems
ok

Check that air is out of the system.