Plastic speedfit central heating system ticking and banging.

[harvey1]

Hi folks,
I've had the micro bore removed from my house and replaced with speed fit. I thought the plastic would cure the ticking as believed it was expansion/contraction but no change. What on earth is going on?? I doubt it's air as the rads don't need bleeding.
I'm baffled and unsure what to do..
Can anyone offer advice??

It's a combi boiler and new rads and the problem is exactly the same as I had with the 8mm copper.

 

[dextrous]

I suppose you've checked that the rads have got their little plastic lugs on their wall brackets?