Fantech

Does this decline in life expectancy Fantech radon vent?

yes, a low flow of air, small pipes won, move as much air as a larger and will create pressure
slowing the fan down and put more load on the engine

The fan runs only provide a small vacuum pump to evacuate the radon in the atmosphere. If a smaller diameter than the pipe will not be as effective overall efficiency of the system will be basically the same in the end if it is improperly installed or protects an area too large house. Can you run multiple 1.5-inch pipe connected to the "3? This is commonly done for the pipe to fit inside 3 1 / 2" studs. It does not follow any rules ventilation, plumbing normal to do, other than on the slope so as not to hold water in a low spot.

You can expect a fan to last Radon 10 or 15 years. Many run longer than that.
The air flow in the pipe will be low, but the overall system efficiency will be reduced if you cut the pipe diameter in half. The cross section of 1.5 "pipe is only 1.77 square inches. A 3" pipe that is four times more, about 7 ". So you have to execute four 1.5" pipes for within the same sector.
Personally, rather than trying to align stolen four holes, I just ran a 3 "pipe in the back corner of a closet. It worked very well because Mercoid gauge was installed directly on the pipe and I could check the vacuum system very easily.

Indeed, it is a squirrel cage fan amperage is less reported in the case of a fan blade Amps increase with more resistance due pipe ,,,,, if sm ck doubt with an amp meter, if its sooo a squirrel cage forward, if it is not a fan