Pumped Bypass Why Would They Have Done That?

Ringbolt

This is an installation in the UK - I cannot get any sensible answers from our forums here so thought I would try the big cousins!
We are running a district heating scheme into a big estate. Normal connection process is to install a low loss header and from there bypass the existing boiler with a motorised valve to the flow and none return valve to the existing return to the boiler so as to prevent the new supply circulating through the boiler. This works just fine. However on this existing system which has a 2" manifold supplying 4 zones the original installer has put in a pumped bypass from the flow manifold to the common return. Anyone give me a reason as to why he should have done that cause I cannot figure it. However I don't want to take it out until I understand the reason why he put there.

plumber1a

Not enough flow is all I can think of, but the pump dosent really serve any purpose.