There are a vast no. of different ecotec variants...the manual I'm looking at has no information for D19...as the Pro models normally have a single speed pump (it's the cheaper model).
So it appears the pump is circulating through the bypass due to your high headloss system.
Get some one in to range rate the heating, cheak the diverter for let-by and setup the bypass.
So it appears the pump is circulating through the bypass due to your high headloss system.
Get some one in to range rate the heating, cheak the diverter for let-by and setup the bypass.