Stop pouring hot water down the drain

Re:Stop pouring hot water down the drain by pingswept on Wednesday March 25, 2009 @06:54PM (#532583)

That's a great idea. Modern gas boilers and tankless water heaters often run their exhaust and intake in concentric pipes, so that the outgoing hot air warms the incoming cold air.

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Re:Stop pouring hot water down the drain by abthomson on Wednesday March 25, 2009 @08:44PM (#532730)

Furthermore, the flow in the two pipes is usually in opposite directions because it's more efficient that way.

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Re:Stop pouring hot water down the drain by pingswept on Wednesday March 25, 2009 @10:38PM (#532870)

I think that the intake and exhaust are always in opposite directions, regardless of whether it's efficient.

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