Removable vent having a filter for use in a building foundation

1. A ventilator equipped to hold an air filter, the ventilator being shaped for placement in a building foundation, the ventilator comprising:

a front of the ventilator, for facing away from the building toward the outdoors when the ventilator is installed;

a rear of the ventilator, for facing into the building when the ventilator is installed;

a ceiling of the ventilator;

a floor of the ventilator;

at least one securing device located at the rear, for securing the air filter spanning the rear; and

at least one manual handling feature located at the front, for removing the ventilator from the building foundation,

wherein the front comprises a perforated grid surface and the rear is open,

wherein the ceiling is substantially flat and the floor is substantially flat,

wherein the ceiling and the floor are at an angle with each other so that the floor and ceiling are farther apart at the front than at the rear,

wherein the front is equipped with at least one drainage area for draining liquid from the floor of the ventilator,

wherein the floor is between the rear and the front comprising the grid surface, and

wherein the front comprising the grid surface is flat and configured for placement substantially flush with the building foundation.

2. The ventilator of claim 1 , further comprising at least one protruding bottom element having a lowest point at a distance from the ceiling that is substantially equal to the greatest distance between the ceiling and the floor.

3. The ventilator of claim 1 , further comprising the air filter,

wherein the air filter is structured to screen out at least most airborne particles greater than five microns in size, and

wherein the air filter is releasable from the at least one securing device, both in a crawlspace and outside the crawlspace.

4. The ventilator of claim 3 , wherein the air filter is slidably releasable along a plane parallel to the back of the ventilator.

5. The ventilator of claim 1 ,

wherein the ventilator has at least two opposite exterior surfaces equipped with oppositely protruding depressible pieces, for securing the ventilator in place,

wherein each of the depressible pieces, in its depressed configuration, is entirely located nearer to the front of the ventilator than to the rear.

6. The ventilator of claim 5 ,

wherein each of the depressible pieces is a leaf spring or spring clip having only one end anchored to the exterior surface, and

wherein the at least two exterior surfaces comprise opposite sides of the ventilator.

7. The ventilator of claim 5 , wherein each of the depressible pieces, in its depressed configuration, is entirely located nearer to the front of the ventilator than to any point halfway between the front and the back.

8. The ventilator of claim 1 , wherein the front is located at least five inches from the back.

9. The ventilator of claim 8 , wherein the front is located at least nine inches from the back.

10. The ventilator of claim 1 , wherein the angle is between two and six degrees.

11. The ventilator of claim 1 , wherein each of the at least one manual handling feature is formed as a flange spaced apart from a solid or perforated surface of the front of the ventilator.

12. The ventilator of claim 11 ,

wherein the flange is positioned parallel to said surface, and

wherein the flange protrudes inwardly, and is spaced forwardly from said surface.

13. The ventilator of claim 12 , wherein the at least one manual handling feature comprises two manual handling features protruding inwardly toward each other.

14. The ventilator of claim 1 , further comprising a perforated grid surface at the front of the ventilator, and a gasket around the front of the ventilator.