This is Turtle.

I got into this on a job when installing hvac system with it. We had a
92+% afue gas furnace to install and had to run a new electric drier
vent to the outside too . we run the two 4" PVC lines side by side and
exited out the eves of the building. It was run 44 feet and 1-- 90
Degree elbow and one 45 degree fitting each on both lines. It worked
fine and was check on the drier like this. We removed the vent line
from the drier and took the temperature of the vent gass. then put the
44 foot vent line back on it and let it run like that for about 10
minutes and check the temperature of the air coming out the eves of the
drier vent and the temperature was 2 degree colder than without the
vent attached.

So you can say 44 feet [ with a 90 degree elbow and a 45 degree fitting
also ] would be a start.

TURTLE