Replace Air Ducts or clean them? Need input please

[richardcp99]

We recently discovered a drain leak in our crawl space. It has been fixed, but I am now trying to ensure I don't have other problems as a result of the moisture.

While under the house I noticed the insulation on the metal duct work was soaking wet from the combination of the standing water from the leak (moisture in the air) and the cold AC in the ducts. My first thought was Mold. I should add that myself and my 8yr old son were just treated for bad sinus infections.

I did a mold test kit and it came back positive.

My questions are:
1. Should I replace 100% of the metal ducts or just clean them and replace the insulation around them?

2. I am leaning toward replacing them, but after reading about the potential problems with varmints (and we have lots of chipmunks around) I am concerned about doing so with Flex Ducting.

3. If I use metal ducting, I am concerned that in Atlanta (high Humidity) I may just have mold regrow due to condensation that may occur.

4. What is the best way to be certain that after I do whatever I end up doing to solve the problem that the problem is actually solved? Consumer reports says those tests are very unreliable.
http://www.consumerreports.org/cro/h...kits/index.htm

My biggest concern is health. Specifically I don't want my family (or myself) breathing in bad/moldy air. But if I am going to spend some $$ I would rather spend more money to solve the problem completely (if necessary) rather than some or less money to just make me "think" it is solved.

A few facts that may be helpful:

• My house is about 40 yrs old and has a crawlspace.
• We replaced the furnace (located in the crawlspace) about 5-6 years ago.
• AC unit is old but still running.
• We've had the ducts cleaned several times over the past 10 years and believe we have an electro-static filter (if that makes sense).

Thanks in advance for your input and expertise.

[targetman]

Do you have attic space for a new system?

[energy_rater_La]

Not an ideal location for ducts, but I understand why you need to remediate
as relocation is trading crawlspace issues for attic issues.
keeping that in mind this is just my advice.

My questions are:
1. Should I replace 100% of the metal ducts or just clean them and replace the insulation around them?
replacing is expensive, and still sealing of seams, joints and junction to supply box can
not be addressed.hard duct has lots of leakage sites. all joints seams and junctions should be mastic sealed. not duct tape or foil tape..mastic.

so cleaning...this entails a lot of work. duct insulation removed, ducts disconnected at supply box. investigation of mold inside of duct..inside of supply box. remediation of mold. I use tri sodium phosphate (sp??) TSP is available at box stores in painting section.
cleaning of mold affected areas. re-attach hard ducting..mastic sealing of all seams
re-insulation with R-8 ductwrap. sealing of insulation so that no metal is exposed (as it will cause condensation). not really something that you would want to diy and finding someone to do this correctly may also be a challange.

2. I am leaning toward replacing them, but after reading about the potential problems with varmints (and we have lots of chipmunks around) I am concerned about doing so with Flex Ducting.
hard pipe ducting is a much better install in crawlspaces than flex. critters like flex
when it gets cold outside flex is a good warm place to raise a family.
an option may be to put ducts in between floor joists and cover with a wire like hardware cloth. whatever you decide..mastic seal of all ducts to stop condensation and duct leakage.

3. If I use metal ducting, I am concerned that in Atlanta (high Humidity) I may just have mold regrow due to condensation that may occur.
if duct leakage is stopped (via mastic seal) the potential for condensation is reduced.
full contact with duct wrap (insulation) to hard ducting further reduces condensation issues. address these issues and mold growth won't occur.

the other side of the issue
how far are ducts from ground?
height of crawl space?
vapor barrier on ground of crawlspace?
is this a vented crawlspace or unvented?
my guess would be unvented.
there are two schools of thought on vented vs unvented crawlspaces.
and it is difficult to properly construct an unvented crawl.

my choice would be to evaluate existing ductwork to determine if it is
worth salvaging. while the insulation may be in bad shape it is the hard pipe's
condition that would need to be evaluated.
if it is in good shape..then cleaning, sealing and re-insulating would be my choice.

best of luck, from hot humid La.

[beshvac]

I am suspitious of the mold testing done, did you do it yourself?.....Mold is everywhere and most tests come back positive. The real results are if a mold test done outside the residense is negative while the test inside is positive?

[TalkingHead]

Take a few minutes and watch the videos at http://www.crawlspaces.org to get an idea of what happens every summer in your climate area. Ductwork located exterior to the conditioned space puts the home under a negative pressure everytime the fan cycles on. Leaks in the floor and attic contribute to the chimney effect occuring all the time. Adding the negative pressure with the natural updraft of soil gases, etc. from the crawl space accumulates the challenge you face to keep you child from being exposed to what is growing under your floor regardless of weather you try to fix or replace your ductwork.

If you really want a solution so that your problem is totally mitigated, spray the underfloor with a mold killer/retarder, take out the old duct, put in new duct according to the highest leak prevention standards and insulation thickness, encapsulate the crawl space after foaming the rim joist, add some insulation around the perimeter of the foundation inside the encapsulation material, seal all floor and attic penetrations and lastly add a dedicated dehumidifier that has a outside air intake controlled by a motorized damper to let in filtered, conditioned fresh air. Now your ductwork is in conditioned space (you save energy) and your moisture problem is solved (you are more comfortable).

[bbjenviro]

Using metal ducts is a good way to go because it is stronger and has less chances of getting damaged. You can apply an antimicrobial to the air ducts like Maintain C-1 for HVAC/Air Ducts and this will prevent the growth of mold and bacteria for up to two years.

[drk]

I'd just clean the hvac system! Metal duct can be cleaned well. You would need to do a two air test to see if you have a mold issue