Dryer Venting Forum

Please login or register.

Login with username, password and session length
Advanced search  

News:

SMF - Just Installed!

Author Topic: Moisture condensing and running under my dryer  (Read 4225 times)

rickharp

  • Administrator
  • Full Member
  • *****
  • Gender: Male
  • Posts: 147
    • View Profile
    • http://www.dryerbox.com
Moisture condensing and running under my dryer
« on: January 10, 2011, 09:39:55 AM »

I am having a problem with moisture condensing and running under my dryer.  I will outline the installation of my ducting and am open to suggestions as to how to solve this problem.  I have 15ft of 4 inch rigid duct on my dryer currently.  There are 3 flexible 90 degree elbows on it.

The duct runs between the interior and exterior walls of my house where it runs through 2 more elbows before being vented out the roof.  The entire vent is clean of debris.  We thought that maybe the air in the pipe was being cooled quickly as it reached the un-heated attic before being vented outside and that was contributing to the condensation problem.  So we wrapped the duct in the attic with insulation so the heated air would reach the roof before being cooled.  This did not solve the problem. 

Can I use one of your special elbow products or do I need to bite off on a vent boosting fan.  I have needed to keep a small rug or towel under the dryer to catch the moisture.  I have an electric dryer and my husband taken it apart and cleaned it thoroughly inside and out and the vent pipe has been cleaned with a 6.5 hp shop vacuum.  So we are confident that there are no obstructions in the duct pipe.  Please email me what you consider the best way to solve my problem. 


Sent in by Kate via email and posted by administrator.
« Last Edit: August 15, 2013, 11:34:58 AM by rickharp »
Rick Harpenau
In-O-Vate Technologies, Inc
Jupiter, FL  33477
561-743-8696

rickharp

  • Administrator
  • Full Member
  • *****
  • Gender: Male
  • Posts: 147
    • View Profile
    • http://www.dryerbox.com
Re: Moisture condensing and running under my dryer
« Reply #1 on: January 10, 2011, 09:40:40 AM »

Two things come to mind in your question: 

You indicated he has cleaned the duct with a shop vac...  has he or has the vent been cleaned with a 4" brush on a flexible rod, similar to the DIY LintEater product.  Merely vacuuming the vent will not clean it like a professional or a good LintEater cleaning. 

2nd, many times the termination itself can be the culprit of poor ventilation.  Many of the older and even some of the newer vent hoods incorporate damper and hood designs that are incredibly restricting. 

See this link:  http://www.dryerbox.com/ratings/dryerfittingschart.htm

The objective of a vent hood for the dryer is basically two fold; prevent back drafts and prevent bird or rodent entry as well as nest building. In facilitating these capabilities a prevalent result is a vent hood that promotes lint build-up and creates excessive back pressure.  It's my hunch that the possible back pressure may be allowing the moisture to accumulate on the interior of the pipe.  I do believe that the insulation wrap in the un-conditioned space will help and should prevent the moisture or sweating, but the slow velocity of the airflow may be something to consider.  If anyone else has any thoughts, please add them.
« Last Edit: August 15, 2013, 11:35:09 AM by rickharp »
Rick Harpenau
In-O-Vate Technologies, Inc
Jupiter, FL  33477
561-743-8696

greenhome

  • Guest
Re: Moisture condensing and running under my dryer
« Reply #2 on: March 09, 2011, 09:59:26 AM »

I typically run into this all the time from DIY. The problem is theere is no way that a shop vacuum with 1,2 or 3 motors will get thru 3- 90 elbows. You will need to actually brush it out and may take several passes to make sure that it has opened up. Then you should test the back pressure with a magnehelic gauge. It should read really no more than .65 water w.c. inches give or take. Also try replacing a couple of elbows with the energy effiecent Dryer L's. You want to make sure that the roof vent damper is not stuck and that there is NO Screen at the roof termination. The lint- alert would work perfectly in your set-up, and let you know when to have it cleaned, due to the increased back pressure. Just my 2 cents

Thanks  Greg from Green Home Dryer Vent Cleaning.
« Last Edit: December 31, 1969, 05:00:00 PM by Guest »