View Full Version : pipe length for basement bathroom fan

02-04-2013, 09:42 AM
I have an unused dryer outlet opening. Now I need a basement bathroom fan. It will be nice to use that existing opening. But it is about 25ft away. Piping from bathroom to that opening is easy. Do you think it is good a idea to have a 25ft long passage for the dump air flowing out the basement? insulate the pipe for condensation concern?

02-04-2013, 01:45 PM
That probably exceeds the manufacturers limit for duct length, but the only way to know for sure is to look at various spec sheets for units you might want. In addition to the total length, you have to add to that for every elbow (change of direction - they slow the flow down, and look like a longer duct). It also makes a huge difference whether the duct is smooth or corrugated...corrugated will make it look MUCH longer.

02-17-2013, 08:07 AM
Corrugated pipe should be outlawed. We never use it. Smooth pipe all the way.

We have installed many Panasonic fans with this longer run and have never had a problem. Removing moist air is more important than living with it because the run is too long.

Try and tape of and insulate the new fan. Keep the seam on the pipe on the top. Always feed from the exterior wall to the fan so that the pipe closest to the outside wall gets the new crimped duct pipe inserted into it. This makes sure you drain properly and do not built up hair balls.