A320 apu
If you look at the APU schematic, portion of the ram air goes into the load compressor than is directed either for pneumatic supply if the bleed control valve is open or vented into the exhaust if the bleed control valve is closed. So essentially the APU always provides bleed pressure. The BCV only controls the direction to which it is going. What I am wondering is if there is supporting evidence that the APU would burn more fuel with the APU BLEED in the ON position. I would think it is the same since RPM and bleed pressure from the load compressor is constant. My airline claims it burns less fuel. They may certainly be right but it doesn't make sense to me. Any inputs/sources?