Replies

1. 
   rjw | Aug 31, 2002 09:41am | #1

   15 feet if each elbow is set to 90 degrees.

   25 feet overall, deduct 5' for each 90' turn.   Of course, check with the manufacturer's installation instructions, they might have different requirements.

   The International Mechanical Code article 504.6 stipulates the requirements for Domestic clothes dryer ducts. In brief, the maximum length of duct permitted is 25 ft. This maximum length should be reduced by 2.5 ft for each 45-degree bend and 5 ft. for each 90-degree bend. The duct should be a minimum nominal size of 4 inches in diameter and shall have a smooth interior finish.

   Do NOT fasten the vent pieces together with sheet metal screws.

   And, for anyone else thinking about dryer vents, do NOT use plastic or foil type vents; they are a fire hazard and gretly increase drying times and energy consumption.

   
   

   ---

   Edited 8/31/2002 2:47:32 AM ET by Bob Walker

1. 
   55512122 | Aug 31, 2002 01:49pm | #2

   Thanks Bob for the info, if I went with 5" pipe - 2 90° elbows its almost 21ft to the side wall of house. Its 3 elbows and 15ft to the front of house (not a good cosmetic choice) and 1 elbow and 19ft to back of the house but thats dropping below the ceiling level in the basement unless I use a dropped ceiling which I hadnt planned to do. Its only 1ft to the inside of the garage. Anyway of going directly into the garage with this vent or I could go through the roof but thats still 20ft or more to get to the back side of that. Thanks Roger

1. 
   DavidThomas | Sep 01, 2002 12:09am | #3

   5-inch duct will have about half the pressure drop as 4-inch duct. i.e. you can have a run that is twice as long with the same back pressure. (But there will be greater condensation in the longer, larger run.

   To add to Bob's helpful points: Don't use "duct tape" on duct work. Use the very sticky aluminum tape sold for that purpose. About $9 a roll, not $3 for the grey plastic/clothe "duct tape" stuff. The reason not to use screws is that it catches fibers in the dryer exhaust.

   David Thomas   Overlooking Cook Inlet in Kenai, Alaska