EXPERIMENT 4:
BUILD A “DRAFTOMETER”
inch length of ¼-inch diameter wood dowel. One foot of “one by two” lumber cut into two six-inch lengths. A few thumbtacks. Wood glue.
What’s a draftometer? It’s a simple gadget that makes invisible air currents visible. You can use it to locate improperly weatherstripped doors and windows in your home, and to pin-point cracks and crevices that need caulking.
Here’s how to build it: Start by drilling a ¼-inch hole near the top edge of one of the pieces of “one by two.” This piece is now the “support” (as shown in the sketch). Next, cement the dowel into the hole. The end of the dowel must be flush with the surface of the piece of wood. Then, cement the other piece of wood (the “handle”) to the “support” as shown in the sketch.
Now, cut a 5-inch by 10-inch strip of plastic food wrap (you will need a sharp pair of scissors to do a neat job). Carefully wrap one end of the strip around the end of the wood dowel, then “windup” the strip on the dowel until only four-inches or so of the strip is flapping free. Push two or three thumbtacks into the dowel — through the plastic wrap — to hold the wrap in place.
The thin, lightweight plastic wrap acts like a “sail”. . . it will respond to the gentlest breeze by bending out of shape. You can blow at it from two or three feet away and make it move.
To detect excessive infiltration (as described in Experiment 2) hold your draftometer near the edges of windows and doors, near passage-holes for pipes and ducts, and close to caulked seams. The piece of wrap should remain motionless (provided, of course, your hand is steady!). Noticeable movement signals poor weatherstripping and/or caulking. Tell your mother or father.
