Replies

1. 
   4Lorn1 | Jul 14, 2005 04:18am | #1

   I would think that knocking in vents would be unnecessary. Get the condensate drain outside and see how it goes for a few months. If the crawl space remains, after that time, damp further steps can be taken.

   Some studies seem to show that vents often let in more moisture than they vent out. At best some only break even.

   Of course a crawl space need not be dead dry IMHO.

2. 
   DanH | Jul 14, 2005 04:59am | #2

   You mean the mold is on the inside of the ducts? Mold on the outside should be of no concern unless it threatens the integrity of the duct.

3. 
   NickNukeEm | Jul 14, 2005 05:44am | #3

   There are companies that clean ductwork, but I imagine it is the rigid variety, not the flexible stuff.  Look in the phone book under Ducts.

    

   I never met a tool I didn't like!
4. 
   brownbagg | Jul 14, 2005 06:35am | #4

   Its a code item here that all a/c drain line must be in a french drain. cannot drain on top of soil.

1. 
   IMERC | Jul 14, 2005 06:37am | #5

   Florida had a requirement that a dry well be installed... approx 55 gallon size.. 

1. 
   edwardh1 | Jul 14, 2005 01:02pm | #6

   South carolina has no such rule- most drip near the foundation edge- you would think it would be a termite and roach problem

5. 
   DaveRicheson | Jul 14, 2005 01:12pm | #7

   I am with 4Lorn1 on this one.

   There have been several recent articles on sealing crawl spaces. That would be my preference. I believe JLC and FHB have both published articles on "how to" seal a crawl space. This may also solve the other problem of mold in or on the flex duct by eliminating the moisture it needs to grow.

   You said "mold starting to appear in the flexible A/C ductwork" 

   Flex duct is hard to seal to rigid duct work and register boots correctly. Generally this is not a problem because the duct static pressure is more positive than the surrounding  area. You loose some heating and cooling air into the crawl space because of the positive pressure in the duct, but don't suck any air into them. My guess would be that the moisture source for the mold in the flex duct is at the air handling unit. Look for loose joints or holes in the return air plenum or ducts side of the unit. If those are locate in the crawl space too they could be pulling the moist air in the crawl into the unit. The a/c unit may be unable to dehumidify that much moist air, and it just passes it on through to the supply side of the system. When it hits the cold metal at the supply register boots it condenses and lays in the flex duct.

   Sealing that crawl space  may solve all your problems.

   Replace the moldy flex duct. It is cheap and easy to work with. Use foil faced tape, not duct tape, to seal the flex duct at transition points.

    

   Dave

6. 
   IronHelix | Jul 14, 2005 01:46pm | #8

   Definitely pipe the condensate out of the crawlspace.  Be aware of where you dump the water at the exterior of the house as it may decide to migrate back into the crawlspace via openings in the foundation wall or simply by wicking through your soils.

   Condensate is notorious for gumming up condensate lines.   Longer/flatter runs are even more troublesome.  Make plans to be able to disassemble and clean by adding unions.  Be sure to support the pvc at every joist or it will "bag" out and become a settlement area and a clog. 

   Have the exit for the condensate drain to be visible on a daily basis...when no condensate is seen running then you will know that the pipe is stopped up and the condensate is spilling out of the A/C air handler and into your  crawlspace.

   Without a visual safety check the A/C could pump hundreds of gallons of water back into the C/S before you again discover the problem.

   If the exterior elevations don't allow for a good flow away from the house, consider installing a condensate pump (~$70) and pump it to a laundry sink or to a place at the house permeter that has a yard drain for gutter. 

   Consider adding a small vent in the ducting system to "condition the crawlspace" by forcing drier air into that space and forcing out the humidity and keeping it dry.

   If the flex duct is moldy...replace it.  Hang it from the joist instead of running it on the crawlspace dirt floor.

   Add a vapor barrier to the crawlspace floor.

   .................Iron Helix

1. 
   DanH | Jul 14, 2005 04:16pm | #9

   Another option is to install a condensate pump right at the AC and pump the water to a convenient drain (or outside). Many pumps come with contacts to shut off the AC if the pump fails, so there's little hazard from that. And the pump outlet line won't clog like a slow-runnng drip line will.

1. 
   constantin | Jul 14, 2005 11:40pm | #10

   Those little pumps are great... we have one in our basement also.I have heard of some techs leaving bare copper wire or a nail in the flow of the water as a means of retarding the growth of micro-organisms. I have no idea if that approach would work, however, unless the water coming out of the condensate pan is acidic enough to keep scrubbing off the patina that usually covers bare, exposed copper.