Boilermate making scary banging noises at night

I've just moved into an 11-year-old house that has a Boilermate 2000 on the 2nd floor (airing cupboard) powered by a Micron boiler in the kitchen. I think there is a cold water tank in the loft too.

The hot water is working fine but occasionally - especially in the early hours of the morning - the system makes the most awful banging/crashing/grinding noises. It only lasts a few seconds and seems to be coming from the vicinity of the Boilermate itself, or the loft above, or in the pipes around these areas. It's waking me up every night and scaring the life out of me. I am pregnant and struggling to sleep anyway so this is really getting to me.

I had an engineer round who is familiar with Boilermates and he seemed to think the pumps and sensors were all working as they should but said it needed a powerflush (£1k+!) We live in an extremely hard water area.

If this will fix the problem then we will pay it but I just wanted to check whether this sounds likely. I couldn't recreate the noise for him while he was here but it really is loud - sounds like something's about to blow up/the roof fall in!

Is it safe in the meantime? It can't actually blow up, can it?!

Well check the loft tank.
And you CAN NOT POWER FLUSH your unit.
The boiler and rads can be if they are disconnected from the unit.
What area are you?
Mike

Thanks - I haven't got a ladder at the moment (just moved in and there's not one attached) so can't get in the loft.

Maybe he meant flush the rest of the system only - he was talking about how long each radiator would take and why it was such a long job. And about how he would need to adapt the pipework on the front of the BM to make it work. Will check.
I am in Herts.

Well he sounds as if he knows ref NOT power flushing the unit.
Why not look on here
List of advertisers see if anyone in your area.
Google up Gledhill repairs for your area.
Or check the tank in loft.
Check unit is full and TAKES water.
Then put a few litres of cleaner in and run it.
When / if it gets better.
Then drain the lot & flush out.
Re fill and add a few litres of inhibitor.
Mike
A grand for a power flush is quite expensive.
Mike