Chaps hi,

hoping for a bit of advice here. I have recently moved house to a
property which was built circa 1987. One item picked up on the survey
was that when the bolier came on (ch or hw) it made lots of loud
banging noises. So it has been doing this for at least 6 months

This didn't bother us too much but now we have started to use the CH
with the onset of winter it is waking us up every morning with a
*very* loud BANG. Having recently had the old analogue programmer
fail (and having to update it and the thermostat myself) I have
decided that it has to be worth an attempt at self diagnosis - and
then possibly trying to fix it myself or get some one in.

I have looked through similar posts but was hoping that this might
make sense to someone out there.

Here is all I can tell you about the system.

System type: Fully pumped, Mid Position valve system, install 1987 by
builders
Boiler: Thorn EMI apollo fanfare i
Pump: Grundfos Selectric (TF110 IP42)???
Mid position valve: Sunvic SD2752

The rest of the kit (stat, programmer etc seems fine)

The bang happens when the heating or HW comes on, normally makes 3 or
4 bangs and then is quiet until the next time it goes off for a while.
I have checked the rads and there is no significant air in the
system, the noise seems centred around the cupboard where the boiler,
pump, HW tank are installed. The bangs seem to travel through the
pipes and it seems that one pipe has now broken the plastic clip it
was in - symptom not cause though I think. The only other thing I can
think to add is that in some rooms as the CH or HW comes on the
radiators make a sort of rattle - like some hard sediment in them is
bein disturbed by the water flow?

Any tips as to what I should look for gratefully received

Tim