Some one (installer) is assuming a lot of things here.
I agree with all the responses so far.
The most important factor with any appliance installation is:
What does the Mfg. installation instruction tell the installer to do and how.
Weekend warriors who modify these installations to do something like this are doing several things:
Assuming to much.
Risk life, health and property!
I have never seen a natural draft furnace converted into a “power assisted” vent unit like this. The Mfg would call this a hazard and not designed for it UNLESS they say it can be done with an approved piece of equipment by their recommendations.
Warranty is shot, done , over ,forget it…
The length (“run”) of the flue is most likely way to long and cools the products of combustion down before any proper venting can take place.
Clearance to combustible materials??? 6" single wall pipe next to ???
The slope of the flue is completely wrong / missing…
The missing draft hood ??
Appliance is most likely not designed for this concept of venting.
Flue “assist Motor” gets controlled by ???
What happens to the flame at the burners when this motor is running…
Premature deterioration of equipment??
Differ that puppy with serious implications of life safety issues.