Last Winters Trials and the Scientific Method

An experience: Having been out of town for BJ Thomas concert, we returned to a burst pipe in our basement ceiling near and exterior wall. Luckily that line had been shut off for the winter and only  a small amount of water escaped. As is custom, I grabbed keyhole saw and began cutting away the sheet rock.

Reflective observation: It seemed that the builder had placed the dryer vent across a water pipe six inches from the exterior wall. The pipe froze and burst right where the venting touched the copper. 

Hypothesis building: It seemed to me that the cold air of winter was being brought into the house when the other vents were running. A range hood vent was next to the dryer exhaust outside. Negative house pressure from bathroom fans, the range hood, and fireplace probably contributed to the problem.

Experimentation:  The dryer vent was re-routed. Actually back into the house via a lint screen and 10 foot silt sock in the mechanical room cycling the moist air back into the house in winter. A butterfly valve was used to exhaust the air to the exterior at another position in summer. We reduced the negative pressure on the house and increased the efficiency of the winter heating and humidity by filtering and cycling the dryer air. This is an electric dryer. Not to be experimented with gas dryers.