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Posted: Tue Feb 15, 2011 9:40 am
by burkhome
If one was to vent the collector outdoors it seems to me that the outgoing duct should be at least the size of the incoming ducts. Is there a flaw in my thinking. Also, if you put a downturned ell outside on the end of the outflow tube would that significantly reduce air flow?
Posted: Tue Feb 15, 2011 10:13 am
by michaeltoc
burkhome wrote:If one was to vent the collector outdoors it seems to me that the outgoing duct should be at least the size of the incoming ducts. Is there a flaw in my thinking. Also, if you put a downturned ell outside on the end of the outflow tube would that significantly reduce air flow?
Size, length, number of bends, etc., all contribute to increasing the static pressure resulting in a reduced airflow. This applies to the intake as well as the discharge (if you can't move air out of the discharge, you can't pull it into the intake).
Since the intake is 4", you really want to go no less than 6" on the discharge if you plan to use more than one port. If you will only use one port at a time, than 4" is fine (standard clothes dryer duct).
Try to use long radius elbows. Each one of these is equivalent to (has the same resistance as) 4' of straight pipe. A standard adjustable sheet metal el is about 6' equivalent, and a sharp bend, or miter elbow, is equivalent to 22' of straight pipe.