air drawn into heatig system?

[drainrod]

having a problem with boiler not heating cylinder or rads
have changed pump, both motorised valves working properly
called out twice over weeknd,aired pump -- sytem works great
par o f&R under floor to cylinder has been piped in using hep20 or polyplumb
not sure if its barrier or not, can air be pulled in through this pipework?
one heating wholesaler hates this pipe
an ideas please

 

[PhoenixServices]

If it is old barrier pipe? You don't say if it a sealed system or open vent?

 

[PhoenixServices]

*Non-barrier

 

[drainrod]

open vent, chance it could be non barrier
los like job was doe by diy