Thread: Mold in HVAC ducts

Ok inspector gurus, I am asking for help again. In February we had the snow in the attic trhough the gable vents problem. Well, that problem has been almost completely taken care of, sheetrock replaced, water stains painted, attic insulation removed and replaced, one gable vent closed off, only waiting on expert opinion on other section of house before closing off second gable vent and getting roofer out to install ridge vent and whatever else the expert says we need to do. Now my NEW problem which I don't know if is related to the old problem or not. When we turned on one AC this year (This will be our 7th summer since we built house) we noticed a horrible smell. Turning it off we called company who installed all 3 units at the time of building. He opened up the furnace in the one that smells and could see black mold growing in it and the ductwork. Closing it back he said to contact a duct cleaning company. (This is from my husband, I was not home at the time) Looking at the unit from the outside I can see black on the pvc drain coming out of it and another unit. The man was told we had a lot of snow in the attic and he said that could be the problem. I have many questions. How would mold get in duct? I know you need moisture and there is dust so therefore mold, but is the moisture from the snow? I can't see how. The ducts are the fexible kind. Is the moisture from inadequate drainage of condensation? I went to check the ends of the pvc pipes that leave each of the units, I thought they were in a closet in garage where hot water tank is but they are not. They go off into the space between garage ceiling and floor of room above garage, could they be tied into bathroom plumbing? If so how would you know they are draining correctly? The company who has been doing the snow restoration is sending out a duct cleaning person next week but I am wondering your thoughts on this because I think well, clean the ducts and if it was not the snow it will just come back. Can those flexible ducts really be cleaned well? Is there someone else I should have inspect the units and the installation? I am sure there were inspections done at the time of building aren't there? Or are those just safety kinds of things they must inspect? I must also add we have hot water floor heat in the downstairs that we used most of the winter this year and the regular units did not come on a great deal. Thanks guys for any input and if you'd like pictures tell me what you'd like to see and I will try to get them for you.

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If he saw a concern in the furnace why does he refer you to a duct cleaning company? Why didn't he try cleaning the furnace first - that should be within his realm of work. How does he know that the air ducts are the real problem?

You're asking the wrong person on that! I agree with you. He just told my husband that there was mold it all 3 furnaces and suggested we contact a duct cleaning service. Then he charged $75 and left. That is exactly what is on the invoice he left I kid you not.

FYI-This is a C&P. The tape lift samples you can do yourself for about $100 for three samples.

Should I have my ducts cleaned?
That depends on the circumstances. The EPA guide "Should You Have the Air Ducts in Your Home Cleaned?" may help you to decide this or you may wish to consult a qualified environmental professional. Tape lift samples taken from inside a supply vent or from the outside of a supply register can often be helpful in determining if the supply air from the ventilation system is contaminated with mold. A good tape lift sample will have a visible deposit of dust, but not be overloaded. Do not run the heater or air conditioner if you know or suspect that it is contaminated with mold. Cleaning should be done by a NADCA certified duct cleaning service following NADCA guidelines.

You obviously do not have an HVAC contract where they come out before winter and again before summer and clean and evaluate the system.

Of course everyone should have a maintenance contract to keep things in good order.

Why mold would be growing inside the unit I do not know. There could be a number of reasons but it would not be from running the heat in the winter unless the unit was not used much and water was getting into the unit, maybe from the snow. Just the idea of heat pumping thru the unit and ducts over the winter should have kept the system dry enough. Most of the time mold in the system comes from backed up AC condensation lines and the water backing up into the unit. Maybe even the supply plenum is lower than the evaporator coil cabinet and when it was backing up it leaked down into that plenum. I have seen that before.

Personaly if I had mold in the ducts of that one system I would have the ducts replaced. By the time you pay for mold cleaning in the ducts and the wear and tear to the ducts it would be worth changing them out. Duct work, if it can be gotten to easy enough, is not all that expensive considering all the money you are about to put out to clean the ducts. The unit itself should be pulled apart as best they can and a thorough cleaning done to it.

Again, this is one of those cases of I guess we would have to be there but I would have the unit cleaned and the ducts replaced. Of course, an HVAC contract in place as well.

In Illinois HVAC contractors are not regulated and we have way too many idiots running under this shingle and a maintenance contract isn't going to protect you from such goofiness. From the info that Charlotte provided I'd say the contractor they had to their home was useless. Charging $75 for doing nothing ain't bad work and many have found this to be easy money - though totally non-professional.

Unless there have been other moisture/mold issues in the home I really doubt that the air ducts are going to be a primary culprit. I can't see where snow in the attic would be a factor in this. That leaves the furnace as the point of initial attention.

The first question I would ask is is there a humidifier installed, is it working correctly, and what is it turned up to? Too much humidity being introduced into the ductwork could easily be causing a mold problem there.

if your tech is just saying there is black mold on all three furnaces and then leaves, you need to do your homework. as posted before about a humifier, is there one on all three. you need to look for where the moisture is coming from. regular duct cleaning is not the solution as they just clean for dust and debris. people on here are going to be asking all sorts of questions. Like what is the extent of the mould as in how far does it extent from the furnaces. the Furnaces are going to be need to be wiped down inside as well as all infected ducts. it is going to be a big job. the other big thing is where and why did you get black mould. was it transfered from one furnace to another is it possible? how did all three get infected as spores can travel via the air but the mositure has to be there for it to grow and pass thru the filters. I could see how one furnace might get affected by a leak in the roof but all three? also do you have mould in other places in the house too? you might want to have a full and proper inspection done for mould as it is a serious health hazard. also you might want to learn more about the drains too. good luck you have a big job ahead of you.

Originally Posted by Eric Barker

In Illinois HVAC contractors are not regulated and we have way too many idiots running under this shingle and a maintenance contract isn't going to protect you from such goofiness. From the info that Charlotte provided I'd say the contractor they had to their home was useless. Charging $75 for doing nothing ain't bad work and many have found this to be easy money - though totally non-professional.

Unless there have been other moisture/mold issues in the home I really doubt that the air ducts are going to be a primary culprit. I can't see where snow in the attic would be a factor in this. That leaves the furnace as the point of initial attention.

So, I guess you feel that in any trade there are folks that do not do their job to good workmanship standards. That's enlightening. I am not sure anyone new that already.

No direct insult intended but that is about the silliest thing I ever heard. I guess what you are saying is that no maintenance is better than some maintenance and someone their every six months to at least do some testing and maintenance and opening up of each system. By doing so they will be performing the minimum task at hand and certainly pick up on moldy drain lines and mold in the units.

Don't listen to that man behind the curtain Charlotte/ You need the systems to be maintained. Doing so will keep your systems running much more efficient, catch items like the units filled with mold, leaks around each unit, components that are on their way out that if not repaired/replaced it will cause further harm to the system as it has here.

One thing I advise clients to do, after their warranty period from the original company is to call a different company in for your maintenance contract. An outside company will be more inclined to tell you what may have been done wrong and suggestions to make it right.

No matter the percentage of companies out there that cut corners there are ten fold that do things right.

Maintenance, maintenance, maintenance or you will pay a lot more in the end when things start going bad. Also a maintenance contract for three systems is going to cost you close to a few hundred dollars per year. Think of it this way. For the systems not being maintained and the heat or AC goes out in one of the systems and you have to pay a company to just get to your home, then pay the company to charge you for the time they spend there and then of course any components. This time charge and trip charge alone could be close to you maintenance contract and in the meantime of not having someone maintain your systems they are running much less efficient and costing you more monthly or a disaster happens like your ducts and system filled with mold.

Charlotte,

Do the ducts run through the attic?

I am thinking the duct work is not sealed nor insulated properly and condensation is occurring inside duct work. More likely the return air side is where this could be occurring but all duct work in the attic should be sealed and insulated.

Duct work replacement can be very costly, and at this point would be contacting duct cleaning company which can sterilize the duct work.

Originally Posted by Ted Menelly

So, I guess you feel that in any trade there are folks that do not do their job to good workmanship standards. That's enlightening. I am not sure anyone new that already. No direct insult intended but that is about the silliest thing I ever heard.

Ted - I couldn't tell you how many clients and homeowners have been dumbfounded by how prevalent unqualified contractors are. What may be very apparent to you and me is not so with those outside our field, at least in my area. As I do with my clients, I was trying to make Charlotte aware of the problem and how vigilance is a prudent necessity. I was under the impression that she is not an inspector. Presenting silliness was not my intention.

Originally Posted by Raymond Wand

Charlotte,

Do the ducts run through the attic?

I am thinking the duct work is not sealed nor insulated properly and condensation is occurring inside duct work............

Now there's a thought. I inspected one house that had the flexible ducts running through the attic, and Raccoons had torn into one of these ducts and had a nice, conditioned air sleeping spot set up inside the duct. A wet Raccoon warming and drying himself up in your ductwork would not only introduce a lot of moisture and mold spoors, but a lot of other things as well!

Ok lets see if I remember all the questions. Yes all the ducts are in the attic, I can see most of them and also had asked the man who just blew in the replacement insulation (from the snow removal) to check to see if any looked like they had been damaged by the folks taking the snow out of the attic. Before the new insulation I could see almost all of them and saw them all during the house building. They all seem to be insulated fine. The Air duct cleaning company came this morning and opened up the units. He showed me black mold growing in the plentum of the main unit. He recommended having the plentum replaced first. It is on top of the unit. He says he can clean and sanitize the others, Did not see any mold in their plentums but also said he may find other issues when they get into the ducts with the cameras. He doesn't do repairs so has no interest in making things worse than they are. Seems very honest and knowlegable. He said it is common to tie the drain into plumbing but did not like how mine went into the space between the floors. Also I noted while in the attic with him there is a roof vent right over that plentum but I did not note any snow there, not sure I looked there really. Also the flue pipe or whatever it is called that goes through the roof was not ever caulked down and I had some snow coming in there. It is not over that furnace but I guess the water could run down that flue pipe. One of the return boxes for that unit was right under a gable vent. Again I did not notice snow there but it could have gotten some. He said it is hard to tell, there was just so much humidity in the house after the snow. Which reminds me of another persons questions. We do not have a humidifyer. And we did not run our heater much at all this year, relying on the floor heat more than we ever have before. Ok my husband, not as wary of the HVAC company who put the units in as I am called and asked them to come replace the plentum in the morning so the duct cleaning crew could come in on Wednesday. He told us it would take all day and his crew would check every duct for openings and issues as they go through them. I am still thinking maybe it would be best to just replace the ducts on that particular unit. How hard could that be? They all seem to be right there.