Fireplace - Misplanning by architects / general contractor

Our fireplace planner has recalculated and comes up with completely different measurements than the chimney supplier of the general contractor. According to him, a total length of 3m would be sufficient, about 1.6m of which would be above the roof penetration. Possibly an L-piece and/or a draft enhancer would also make sense. At least that's what we think.

We definitely want a fireplace. We've already bought it anyway. There's no way around it and we don't want an aquarium in the living room.
If the chimney can be shortened using these mentioned measurements, that would be good, then it wouldn't be quite as ugly.

Our fireplace planner has recalculated and comes up with completely different dimensions than the chimney provider of the general contractor. According to him, a total length of 3m would be sufficient, of which about 1.6m would be above the roof penetration. Possibly an L-piece and/or a draft enhancer might make sense then. At least that's what we think.

Well, then I wish you luck that the planner is right. A more discreet chimney does look better after all