Worcester Highflow and saga of clunking tap

Just had a worcester highflow 440 installed and now have serious clunking in hot taps to the point that the HepO2 pipe whips.....the clunk occurs both when tap is opened and also closed. Tap is a Grohe mixer.

Pressure runs at 3+bar depending on the time of day.

Everything was fine for first two days then bam felt like the mother in law had dropped the kids off at the pool whenever I ran the bath.

Is the pressure too high?, the pipes arent particularly well secured in clips, help

Hot system was very low pressure before the installation of the combi which now delivers 20l/min hot water

You seem to be suffering from Tap hammer.
Ask your installer to come back and check your main stop cock. it will probably need replacing.

cheers

installer came back this am and the fault lies in the fact with the old storage tank having been removed this has meant the old pipes are now less secure (they were never clipped!) and are moving more freely causing the clunking when the taps are turned on. Cuts a whole in ceiling and will be tidying up pipes and securing them.

'spose you have to expect tis type of thing in old house just glad it aint barrel steel pipe!