i can certainly give you examples of o ring problems on boilers for example britony combi ,all the parts held in by o rings .
Look at all the plastic fittings hep 2 0 ,polypipe ,jg speedfit .
Unanimously jg speedfit the worst for leaking and that is what magnaclean has picked
In my experience, the worst for leaks are Polypipe, lots of new builds up here last about 3 years then the patches appear in the ceilings, almost all of them have been polypipe fittings.