Bonding Query r.e plastic plumbing fittings

[LlandrilloSpark]

Changing a CU in a bungalow at the moment, Main Bonding to gas and water are in place and continuous, I get below 1ohm on R2 testing the taps and sink, however the radiators show no connection to earth.I've pulled up a small section of floor that the plumbers cut out, I shone the halogen underneath and thru the honeycomb Walls I can see plastic fittings, I presume this would be the culprit which is breaking the bond? And if so is the only solution to supplementry bond each side of each fitting?, which to be honest is impossibleRCD,s are installed

 

[truckster]

If theres no connection to earth why bond them?

 

[Sparky Ninja]

If RCD's are installed then refer to 415.2.2 and I doubt you will have much of a problem with the measurements you've already taken.