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4\" vent question

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Steve Ebels
Steve Ebels Member Posts: 904
Maximum dryer vent length with ridgid aluminum pipe. 40 ft with each elbow counting as 5' in length. Maximum recommended flexible duct length 25'. They also say to avoid the flexible duct if possible.

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  • jim_14
    jim_14 Member Posts: 271
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    4inch vent/duct question

    A bit off topic but I figure this was the best place to ask.

    Im redoing the vent from my gas drier, going from a temporary installed mostly flexible duct set up to a more permanent rigid vent setup. Because of the length, about 25 feet, and b/c it runs near the boiler and HWH and venting Im redoing it with rigid ducting.

    I used a 4 inch aluminum duct connector but I had alot of trouble getting the ends of the rigid duct into the connector. I wound up crushing the both ends a little to get them to fit into the connector. I would of thought the connector would be a little oversized or undersized to allow for a smooth connection.

    WHat do you guys use, brand wise? I bought this is HD, am I doing something wrong?
  • Steve Ebels
    Steve Ebels Member Posts: 904
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    Don't know

    What you are refering to by the term "duct connector". We use standard aluminum 4" dryer vent pipe and elbows. If you are connecting ridgid pipe to a piece of flex, it wouldn't be abnormal to have to crimp the end of the pipe a little to get a good fit. Remember to tape the joints. Do not use screws on dryer vent as they will catch lint over time and restrict the airflow. (Can we say 2 hour dry time for a load of clothes?) If the pipe doesn't fit from joint to joint, take it back and find another place to buy your stuff. A fair amount of merchandise that HD sells is second quality stuff that they have gotten a good deal on from a manufacturer. Ran into that scenario just this past week. Hope this helps.
  • Harvey_5
    Harvey_5 Member Posts: 7
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    Dryer venting

    Consider running the vent out the whole way in ridgid
    aluminum pipe, I did this in a few places and had good
    luck with it. Buy a role of aluminum tape to cover your
    joints instead of screws or rivets. If possible try to
    find the shortest route possible. Hope this helps.

    Harvey
  • Larry (from OSHA)
    Larry (from OSHA) Member Posts: 717
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    dryer vent

    Jim,

    If you have more than 2 90* elbows, you start to lose a great deal of flow rate. Something like 25% or 50% for each 90 (if memory serves me). For long runs consider going to 6" duct. Costs more, but you end up with dry clothes. Good luck

    Larry
  • Fred P
    Fred P Member Posts: 77
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    does a 90* elbow thats attached right to the back of

    the dryer count in your flow rate loss calculations?

    6inch duct is a consideration if I have the space once my new boiler and HWH are installed. I have 3 90* elbows currently if you count the one I attached to the rear of the dryer. I absolutetly cannot avoid the 3 elbows in my run

    Does the rectangular flat duct (aka space saver duct with 4inch openings) reduce flow rate?

    What about a combination of 6 inch and 4 inch? Do I gain anything from a partial 6 inch duct run?

    Unfortuantly I inherited a plastic duct run that was buried behind the walls during previous owners basement renovation years ago and it was full of line, long drying time and a fire hazard.. My current setup greatly increased my drying effiencentcy but its a sloppy flexible aluminin duct run.
  • bruce pirger
    bruce pirger Member Posts: 111
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    While on this topic....

    Since we are talking about dryer ducting....

    Do you need to worry about heat and dryer ducting? Can you run dryer duct through a stud wall, i.e. place the ducting along a stud a cover it with drywall?

    Can't imagine a dryer duct can get that hot...but I guess I don't know. I do know that lint can ignite when it is left incleaned in a dryver vent for years...

    Thanks.
  • Larry (from OSHA)
    Larry (from OSHA) Member Posts: 717
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    vent

    Jim,

    Yes, all elbows count. Check out this link and scroll about half way down:

    http://bob.appliance411.com/links/jump.cgi?ID=778

    And yes, some 6" will be better than none as it is easier to shove air through a larger duct than a smaller one.

    Larry
  • Fred P
    Fred P Member Posts: 77
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    If the dryers output duct is a 4inch opening will upsizing it to

    6 inch make a difference?

    I just realized that when I make this a permanent run there will be about 5 or 6 elbows (to get around walls and to rise from the floor up to about 4 feet and then turn straight) Theres just no way around that unless I take shortcuts (flexible duct to avoid a few elbows).. It might be worth it in this case to go flexible for part of it.

    Do they make 6inch flexable duct?

    What are your thoughts about installing a lint trap at floor level right before the ducting takes a 90* turn vertical to go over boiler? That might help with lint collecting at floor level right at elbow bend??

    Lintrap was found via this link:
    http://www.fantech.net/accessories3.htm
This discussion has been closed.