Upstairs heating

[Bomber74]

Ok I have a dual oil and back boiler system. Ever since I moved into this house of horrors I’ve had no heating upstairs. Downstairs rads ok but nothing upstairs . No air in system and all valves open. Can’t figure out why no pressure upstairs. Had the whole system professionally flushed as well and both circulating pumps working 100%. Any help much appreciated

 

[king of pipes]

It hard to see from your pictures how and where the pipes go but I see at least one non return valve there could be another ? these can become stuck or blocked with debris I think you will need a engineer who understands combined heating systems to diagnose and solve your problem. Kop