Radon system

Could you be a bit more specific? Is this to be in the actual basement, or is it to be installed in gravel under the basement slab?

If it is in the actual basement, the objective is to keep the basement air pressure slightly below the rest of the structure. This can usually be accomplished rather simply with an exhaust fan which is adequate to ensure that air is always drawn into the basement from the rest of the structure and from outside -- with the exhaust, obviously, not near the intake vents. There are several real cautions with these. One of the less obvious is that they are incompatible with whole house exhaust fans -- the two fight. They may also be incompatible with such things as kitchen or bedroom exhaust fans -- if those are present, the basement exhaust fan must be more powerful than any combination of them. A less obvious precaution is that any fuel burning appliance in the basement -- such as a boiler or furnace, or a water heater, will at the very least require adjustment for it, and will be better served by having a dedicated outdoor air intake.

The underslab variety is much simpler -- consisting of a couple of feet of gravel, not isolated from the underlying soil, with perforated pipe -- 4 inch drain is just fine -- running through it and leading to a dedicated exhaust fan.

In both cases the exhaust fan, of course, is running all the time.