On Sun, 06 Feb 2005 14:35:47 GMT, Larry Kraus
wrote:

How do I set up my ducting to allow for expansion?

I leave an extra "wye" fitting at every dead end, with a short piece
of pipe and a cap duct taped to the extra hole.. Adding more duct is
easy. My system is PVC, so the fittings are cheap enough.

The extra opening also facilitates removing the occasional blockage.

Barry