[TowerTalk] where the condensation comes from

[StellarCAT]

Thanks Jim, But I’m not sure many would use 2” pipe... 3” minimum – and I’m thinking of 4” so the cross sectional area would reduce the flow/area correct? Also if at the ends where it is open that opening is pointing down and the open face is horizontal to the ground. Any air across it as far as pressure is concerned will be greatly reduced – if anything it would be a venturi effect sucking instead of blowing I’d think.  Gary    I did a bit of calculating about what might push damp air into a conduit.

I assumed that I had 30 meters (100ft) of a 2" diameter tube where there was a pressure difference corresponding to a 10 mi/hr wind (it's about 1/4 lb/sq ft) 
You'd get a flow of about 2 liters/second (which is surprisingly high)

In an hour, then you'd have 7200 liters. If you had 100% humidity air at 68F (20C) going in, and the soil was at 50F (10C), you'd be condensing out about 50 grams/hour. 
In reality, you probably don't have 100% humidity at 68F. But you might have 50% humidity at 85F, and that's about the same amount of water.