What does airflow in the sump pit mean?

Question

I have a sump pit in my basement with a pipe that comes from the drain tile. The drain tile does not see day light anywhere, it's all near the footings of the foundation.

I can feel a strong flow of air coming from the pipe. Where would that be coming from? Is that normal?

Here's a picture. The top of the picture is the exterior wall of the house, the pipe is coming in from the drain tile.

So cold air is falling thru your drain tile. No big deal. What are you concerned about? — Carl Witthoft, Nov 28 '16 at 18:11
Could be a broken natural gas line in close proximity to your drain tile. Is there any odor? — Billy left SE for Codidact, Dec 12 '16 at 23:36
@CarlWitthoft I could imagine myself asking this same question because it would be very disconcerting to feel air blowing out of what I presumed to be a closed system. Somewhere my presumption was wrong and I would want to figure out how. — Zach Mierzejewski, Jan 24 '17 at 13:01

Benjamin Lane · Accepted Answer · 2017-03-25T18:38:47.590

I am a residential builder, but I would suspect this "air flow" is best explained through psychrometrics and the concept of "natural draft".

The air inside the drain tile system will likely be much cooler than the temperature in the basement. That temperature difference begets a pressure difference, with the cooler air being more dense than warm air. Nature, forever seeking homeostasis, tries to reconcile the pressure difference between the two areas..... and a draft is formed.

This phenomenon can also be known as the "stack effect" when dealing with building construction, and is one of the causes of thermally inefficient homes. Improperly sized HVAC systems and things such as ventilation fans in bathrooms and range hoods will also serve to depressurize the house.

From a building inspector's point of view there is absolutely nothing to be worried about.

score 0 · Answer 2 · answered Dec 20 '16 at 17:33

Usually sump is used for various reasons. In a tropical/sunny regions water is harvested into the sump that falls on the roof during rainy season so that ground water gets replenished in between concrete jungles (cities).

Check when that kinda pipe is running nearby your surroundings. Sometimes air does flow due to tunneling effect based on seasonal changes and that none can tell. Another reason why that put holes are there is if the pit gets overflowed it will come out through that and passage of air instead of different atmospheric pressures when it's dry. Pit is made of different layers of soil like gravel sand charcoal etc etc for filtering the waste water from polluting ground water or water bodies nearby.

Else someone has a underground basement and it's for ventilation :p

What does airflow in the sump pit mean?

2 Answers2