Properly connecting a dryer to an outside vent terminal is not as simple as it might seem. You need to be concerned with the total length of run of the pipe, the type of pipe you use, how many bends are in the pipe, and the design/shape of vent terminal at the end of the pipe.

The dryer blower only produces so much energy. This energy is offset by friction within the vent pipe. This is why you must be concerned with the total length of the pipe. Ninety degree angles also create friction. Each bend equals the friction the air would encounter if it ran through an additional 10 feet of straight pipe. Smooth metal pipe offers less friction than flexible pipe with lots of little ridges within the pipe. The vent cover shape and design is important as it also acts as a partial dam or blockage to the exiting air. A vent with a wide mouth opening say four inches or so or one with the little louver doors that swing wide open offer the least resistance. The smaller the vent opening the greater the amount of final resistance.

Use the tables below to calculate how far your vent can be from the dryer. Pay attention to the type of pipe you have and the vent configuration!

Vent cap with wide four inch opening or mini-louvers and smooth metal pipe

• Total Pipe length can be 64 feet with No bends
  
  
• Total Pipe length can be 54 feet with 1 bend
  
  
• Total Pipe length can be 44 feet with 2 bends
  
  
• Total Pipe length can be 35 feet with 3 bends
  
  
• Total Pipe length can be 27 feet with 4 bends
  

Vent cap with narrow 2.5 inch opening and smooth metal pipe

Vent cap with wide four inch opening or mini-louvers and flexible ribbed pipe

• Total Pipe length can be 36 feet with No bends
  
  
• Total Pipe length can be 31 feet with 1 bend
  
  
  • Total Pipe length can be 27 feet with 2 bends
    
    
  • Total Pipe length can be 25 feet with 3 bends
    
    
  • Total Pipe length can be 23 feet with 4 bends
    

  Vent cap with narrow 2.5 inch opening and flexible ribbed pipe

  • Total Pipe length can be 28 feet with No bends
    
    
  • Total Pipe length can be 23 feet with 1 bends
    
    
  • Total Pipe length can be 19 feet with 2 bends
    
    
  • Total Pipe length can be 17 feet with 3 bends
    
    
  • Total Pipe length can be 15 feet with 4 bends
    
  
  
  

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  Comments: Welcome! I, Tim Carter, don't answer questions here. If you post a question here in the Comments Area, perhaps another visitor will help you. You need to go to the Ask Tim page if you want a question answered. Once there, look closely at how many weeks behind we are. Please be patient as you use this free service. If you have an emergency and need to talk to me, there is an option there for you. Steve Geller 18 Dec 2007, 21:54 Thank you for the information. I don't often say it. big al 02 May 2008, 09:19 how far does an electric dryer have to be from an opening window? Sterling Schwab 14 Jun 2008, 17:02 My wife and I just bought a house with the washer & dryer are in the basement. Previous owners vented the dryer directly into the basement (for who knows how many years), so there is lint fibers everywhere hanging off everything. We bought a new dryer, a Frigidair Galleria. The washer & dryer hook ups are at the front of the house. I would like to vent the dryer shortest possible length, which would be onto our cement and block front porch. To do this I would have to run the vent pipe up the basement wall about 8 feet, then snake flex tube thru the homes front face plate, go between the interior and exterior wall another 1 foot, then 90 degree turn thru the exterior wall where I would install the vent. Is this the smartest thing to do, or should I run horizontal 15 feet in the basement, thru cement block into the garage, put in a 90 degree turn, then out of the garage wall. This would avoid the porch scenerio, but I would have a lot of dryer piping. What do you think is the smartest thing to do in this case? jc 29 Nov 2008, 08:29 I have bought a house(50's) that has the dryer located in the center of the house and really as far as the plan goes this is the best place for it,but the vent is directly into the subfloor not to the outside....anyway I have to vent it out and thats about 20-30' away using smooth galv pipe w/2-3 bends right?or even up thru the roof possibly? need opinions please... thank you jc brian 17 Jan 2009, 13:23 can two 4" dryer vents be tied together on one 4" line Nick 26 Mar 2009, 17:05 There are three different vents above my dryer, only one of which my dryer is connected to. The other two aren't connected to anything, and when I put my hand underneath them I can feel cold air coming through. Would it be okay to block these two vents, or would that have any negative outcomes.      View all comments *Name: Email: Notify me about new comments on this page Hide my email *Text: Security Image: Security Image Text:   Remember, Tim Carter doesn't answer questions here in the comments. You need to go to the Ask Tim page.