Hi everyone, new member from Canada

[clarence kohut]

I joined looking to try and solve an ice build up problem on the air intake of my HE furnace which is vented through the chimney. The exhaust extends straight up about 18" above the intake which has a 90 degree elbow down.

[Claude Lawrenson]

From a "google" search
http://www.totalairsupply.com/files/9%20November%2007%20Venting%20&%20Draining%20Condensing%20Furnaces.pdf