Catalyzes the NADPH-dependent reduction of long chain acyl-CoA (with chain lengths of 14 to 22 carbons) to the corresponding aldehyde. CoA + hexadecanal + NADP(+) = H(+) + hexadecanoyl-CoA + NADPH Belongs to the short-chain dehydrogenases/reductases (SDR) family. Extended N-terminus.