Thread: New HVAC Ductwork

Hi everyone, I just joined. I have a 25 year old house and there are rooms with excessive dust in them. My wife complains of light headedness/dizziness ever since we moved in to this house. We've talked with several contractors who suggested replacing our ductwork as a fix for these issues (including one that was on site to clean our ductwork).

So, my question - are replacing the ducts a good idea and will it solve our dust problem? What is the likely cause of the dust issue? We had both a/c units replaced 5 years ago so the unit nor the coils should be he problem. I live in Houston, TX.

Thank you in advance for any help.

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While the ducting may need cleaning, I would strongly suggest you have the furnace thoroughly checked to ensure there is no CO (carbon monoxide) spillage and the furnace is operating properly as designed.

Headache and dizziness are symptoms of CO poisoning so you would be well advised to rule CO out as the cause of the headaches

As to duct cleaning..

http://www.cmhc-schl.gc.ca/publicati...ech/95-205.pdf

Phil, Air ducts do not create dusty rooms - they circulate dust that is already there. You wife's headaches MAY be due to the dust but I wouldn't hone in on that as being the only contributor. The dust may be a starting point for you. Are the housekeeping efforts satisfactory? How about your vacuum cleaner and it's filtration system? What's the condition of the HVAC evaporator coil? What is the exterior environment like - pesticides, fertilizers or nearby commercial / industrial operations? Was the home contaminated with something prior to your owning it?

Needless to say things are not always cut and dry. A qualified indoor environmentalist may be able to offer some guidance. You may be able to find one through iaqa.org.

People have different sensitivities. CO can easily be identified and/or eliminated as a cause. I suggest that you fork out some money to have an environmental study done in the house. The cause of her dizziness may have nothing to do with ductwork.

Phil,

It could be a number of different issues. Do your wife's headaches occur only in the winter or are they year round? If they only occur in the winter it could be CO but then again CO should also effect you. If it occurs all year long it could be something as simple as not enough return air - unit would then draw dust and heated air from the attic. You could really use a professionally done energy analysis. But be careful because there are a lot of "energy analyst experts" out there who actually know very little!

Site sages here have already opened many possibilities for you. The one I favor is that the dust and the physical symptoms may not be symbiont. The dust could be a product of the heating system being in use while drywall sanding was happening; even if many years ago.

The 80’s were not exactly a stellar time for building here in the Houston area and if you have the original ductwork still in place then there is a good chance that some replacement and/or modification will be warranted.

One thing to keep in mind though is that the HVAC system is sometimes just the conveyance system for dust that is already in the house. In other words, a source for the dust may exist somewhere else in the house and the HVAC system is simply moving it around as the system operates. Even brand new tightly sealed ducts are not going to solve this kind of problem.

Having said that, it is true that a poorly sealed and/or designed duct system can be the reason that dust is being brought in. The trick is trying to figure out what is going on and what needs to be done to address the issue(s). Toward that end, you really should have someone qualified come out and have a close look at your HVAC systems before you decide to replace the ductwork.

Also, solving problems with your duct system do not always require replacement of the ducts. Sometimes a good re-sealing and/or design flaw correction is enough to get the job done. If you do have an older duct system though then the odds of needing to replace all or part of the duct system do tend to go up.

What remains to be seen though is if a problem with the duct system is the cause of your wife’s symptoms. If your existing duct system is contaminated with something to which she is sensitive then there may be some relief to be had if you do in fact replace contaminated ductwork.

You also mentioned that you had someone out cleaning the ducts; did that do any good at all in regard to the dust accumulation or your wife’s circumstances? Another question that comes to mind is what kind of ductwork do you have (flex duct, metal duct, ductboard)? Were they able to clean all of the ductwork including the plenums or did they just clean what they could reach with their equipment from the supply grills? What about the air return side of the systems? Did they clean those areas as well?

Thank you all for the replies and helpful tips.

Phillip, to answer your specific questions, the air duct cleaning company never cleaned our ducts. They said it would be a waste of money and just recommended replacement (a service that they of course provided). I have flex duct but as I mentioned it is original (25 years old).

If I do decide on replacement, should I get the new ducts hung? I do not understand the benefit of hanging ductwork and I've been getting conflicting information as to whether this is even code or not (I live in unincorporated Harris County, not within Houston city limits).

Thanks to everyone again.

So they won't clean the ducts but they are willing to replace the ducting at considerable cost. Find another company.


You did not answer my question as to when and if you have had the furnace serviced to ensure its not spilling CO?

Originally Posted by Raymond Wand

So they won't clean the ducts but they are willing to replace the ducting at considerable cost. Find another company.

You did see that he has flex ducts.
They may not need to be replaced, but I would not clean them.
To likely to damage the ducts, then they must be replaced.

For the OP:
Should You Have the Air Ducts in Your Home Cleaned? | Indoor Air | US Environmental Protection Agency

The ducts are required to be properly supported as per the manufacturer's installation instructions and 2006 IRC 1601.3.2.

Also see: http://www.flexibleduct.org/images/ADC~IR5E.pdf (4.6, Figure 19)

Also refer to ACCA Manual D.

And yes, these regulations apply even though you live in Texas outside of an incorporated area.

Why are you in such a hurry to replace ducts when you still don't know the source of your wife's problems? You need more information in my opinion. Most people never clean their ducts and never have any health issues associated with dirty ducts.

Yes thanks Rick I did see that there are flex ducts, my concern was with the supply trunks.

Yes definitely the ducts should be suspended out of contact with the attic floor (and each other) if they do end up being replaced. I can also tell you from experience that a 25 year old flex duct system is rarely worth cleaning if there is a problem with dust or mold contamination. I for one would not find fault with a company for giving (what is in all likelihood) an honest assessment of the cleanability of flex duct from that time period.

I also doubt very much that there are any trunk lines in the house. That vintage of duct system around here is almost always all flex from the supply plenums to the register boxes and is also very likely to be the old gray vinyl duct material. I would also hazard to guess this is a two story house since it has two HVAC systems so some portions of the duct runs will be enclosed in inaccessible wall and ceiling spaces.

If this is the case then it is not likely going to be possible to replace the duct system in its entirety without cutting out some drywall. Most HVAC contractors are not going to want to do that and may suggest leaving the inaccessible ductwork in place and replacing everything else. That is not an entirely unreasonable options as ductwork in those inaccessible spaces is typically in better physical condition because its been protected and not subjected to abuse and the harsher conditions of the open attic.

But! If there is a contamination problem within that inaccessible ductwork then you are back to the issue of trying to clean it, assuming that portion of the ductwork is in good enough condition to survive the process, or biting the bullet and removing some drywall in order to facilitate a more complete replacement.

All in all there are going to be some tough choices to be made and you can bet that none of them are going to be cheap when its all said and done.

Thanks again for the replies.

Raymond, my wife's problems are much more pronounced in the Summer; we have 3 CO detectors in the house and we regularly service the units. Her condition is something allergy like (dizziness, morphing sometimes into vertigo, no headaches). It was noteworthy because it happened once we moved to this house, although that was nine years ago. And we did not accept the bid from the company that tried to sell us new duct work as they were high anyway.

Eric, for the questions I can answer, I think we are ok. I am not near an industrial area nor are aware of any type of previous contamination, and housekeeping efforts are acceptable. The dust seems to be ok in all parts of the house except for the master bedroom and bathroom where I have to vacuum the WALLS for dust build up once a month or so. I mean, that seems crazy to me.

Bob, you may be on to something. What you said about the lack of return air really makes sense to me; that was also echoed by one of the contractors we brought in, although he didn't really explain it that well, just saying the extra return "would fix my dust problem". At some point after the ductwork the previous home owner had cellulose insulation blown in the attic, and that stuff seems to be very dusty. in many cases a thick covering just sits on top of the ductwork. but, please help me understand..how would the system be pulling from the attic if it was a closed system though?

Phillip, you are correct about the HVAC infrastructure and the fact that we have a two story house, except there is a trunk line in our attic, coming out from a 4 ton unit we have supplying several areas, most notably the "dusty" area. I do not know about the grey vinyl ductwork (it is silver on the outside) but all companies with which we've discussed bids have stated that they will only replace what is in the attic and not what is in the walls. They will cut the ductwork and reseal the existing (in the walls) ductwork to new ductwork with sleeves/connectors.

I am not totally convinced these ducts are the root of my wife's issues but am really sick of the dust in our master bedroom (all ducts to this area can be replaced). I do also have damage to the ductwork; I had an energy analysis and know that we have leaks, there is at least a couple of tears in the ductwork and one place where a rat chewed through the ductwork (now covered with the silver tape, but jeez, how nasty is that that the rat was getting in there). We brought in pros to get rid of the rats, which worked but still leaves the damage. I can also get some fixes to the original crappy design of the ductwork as two rooms do not cool as well as the rest of the house, which all four of the companies we brought in noted is a simple design issue that can be fixed with some minor changes to the ductwork. Lastly I can go from R2 to R8 ductwork which will save some dough in the Summer, although I am under no illusions that this will economically pay out.

So, I apologize...for expediency I stated in my original post that the reason for considering the change was because of my wife's issues. More completely it is everything I stated above - energy savings, better and more efficient design, fixing the dust problem, cleaning the ducts, general indoor air quality, more filtration (adding in new box filters) and hopefully (but not assuredly) fixing or improving my wife's condition.

Once again, I thank everyone for giving their time to help with the issue and to point me to the right resources.

Phil thanks for the update.

A couple of things come to mind.

1. Off gassing of cleaning products, cosmetics, dry cleaning, paints, aerosols and furniture glues, can cause problems for the hypersensitive.

2. Other undiagnosed medical conditions can be causing symptoms.

3. As you may know you will never eliminate dust, even the best air cleaners won't do much to eliminate it.

4. Installing a HRV, (Heat Recovery Ventilation Unit) may be beneficial by introducing fresh air into the house and expelling stale air.

5. About the rats... they can leave their feces and urine in duct work or other parts of the house and that could also create allergic reactions.

Good luck.

Hoping to explain a little about the need for return air grills in the master bedroom.
If you have air blowing into the room, you have to take an equal amount out in order for the system to heat and cool properly. If you don't have enough return air to balance the supply then it will force leaks around light fixtures, plumbing penetrations, under walls, etc. There will be air leaking out of the rooms with higher pressures and air leaking in at the rooms with lower pressures. Typical tract homes rely on undercutting of the bedroom doors to provide a return air path (a cheap but not very effective method) while better systems will have both supply and return air in every space that can be closed off (i.e. bedrooms, offices)

When air leaks out into the attic or outdoors, a corresponding amount of air is drawn in from the attic and outdoors, so yes you may be drawing in cellulose or dust from the attic because of the lack of proper ducting and damaged ducts. While the ideal house and air conditioning system is a "closed" system, in reality, neither is truly a closed system because of imperfect ducts and building envelope.

Originally Posted by Phil Marlino

... At some point after the ductwork the previous home owner had cellulose insulation blown in the attic, and that stuff seems to be very dusty. in many cases a thick covering just sits on top of the ductwork. but, please help me understand..how would the system be pulling from the attic if it was a closed system though?...

I suspect you have an air-starved negative pressure situation. Open attic not entirely open (perhaps not chuted, insufficient make-up air), turbines and/or mechnicals. Exhaust activities from within the occupied space drawing air & particulates from unsealed walls and ceiling communicating with attic. Sucking in from attic to house whenever your air handler fan or exhaust fans, dryer, etc. are running.

If the rats were gnawing on the flex duct insulation, likely were also through kraft and other draft stopping materials (if present) beneath original insulation to floor/ceiling cavity and/or in walls.

IIRC still unresponsive regarding last full inspection, cleaning of entirety of mechnicals in attic space including main fan, coil, and assuring wall cavities acting as return aren't blocked/full of insulation.

Suspect raking back then pulling back existing insulation would be enlightening, as would inspecing sofit venting/chutes if present, etc.

IMO, its telling the symptoms increase in the air conditioning months, and that the dust collections on the upper walls & ceiling of the 2nd floor - suggestive of bypass non-continuous moisture retarder/draft stopping/blocking and blocked, restricted or insufficent air intakes in open attic, and blocked, restricted, or insufficent returns and make-up air.

Phil,
Your wife's symptoms being worse in the summer are possibly a result of the increase air flow (higher fan speed to push cool air).

If you have had a mouse/rat problem. The urine and feces left behind can be a problem of sensitivity. Inside and outside of the ducts

The system may be dragging contaminants into the ducts by way of the increased force from the AC settings. Especially if the ducts have been compromised by rodents.

Have you thought about putting some filtering on the supply registers to catch the dust as it enters the room? Something as simple as the filter cloth used in window ACs.

Thanks to all once more for all of the great information everyone posted. I am going to pursue an analysis of the air balance issue in the house as many of you all suggested. Is there a specialist that handles this type of work, or should I just rely on an a/c company to do the analysis?

Put the filter at the furnace. Dust issue is resolved.

Originally Posted by Joe Funderburk

Put the filter at the furnace. Dust issue is resolved.

Not necessarily Joe. That is a very broad generalization on your part. The air handling system does not have to bring the dust through its intake ducts and discharge it out of the supply ducts in order to have an impact on its ditribution/accumulation problems.

There are many factors that can allow the HVAC system to bring dust into the home and move it around the dwelling that do not involve the dust actaully having to travel through the mehcanical system itself.

Originally Posted by Phillip Stojanik

Not necessarily Joe. That is a very broad generalization on your part. The air handling system does not have to bring the dust through its intake ducts and discharge it out of the supply ducts in order to have an impact on its ditribution/accumulation problems.

There are many factors that can allow the HVAC system to bring dust into the home and move it around the dwelling that do not involve the dust actaully having to travel through the mehcanical system itself.

I don't understand that. I have electronic filters at the furnace in my Trane system. That design seems better to me because any leakage that may be present in the return ducts get filtered at the end of the return before distribution via the supply side. Any dust in the air return never gets past the filter to be distributed via the supply system.

That said, flex ducts don't last forever, especially those in a hot attic. I don't know if they are actually deteriorated.

Originally Posted by Joe Funderburk

I don't understand that. I have electronic filters at the furnace in my Trane system. That design seems better to me because any leakage that may be present in the return ducts get filtered at the end of the return before distribution via the supply side. Any dust in the air return never gets past the filter to be distributed via the supply system.

That said, flex ducts don't last forever, especially those in a hot attic. I don't know if they are actually deteriorated.

From earlier in this thread:

Hoping to explain a little about the need for return air grills in the master bedroom.
If you have air blowing into the room, you have to take an equal amount out in order for the system to heat and cool properly. If you don't have enough return air to balance the supply then it will force leaks around light fixtures, plumbing penetrations, under walls, etc. There will be air leaking out of the rooms with higher pressures and air leaking in at the rooms with lower pressures. Typical tract homes rely on undercutting of the bedroom doors to provide a return air path (a cheap but not very effective method) while better systems will have both supply and return air in every space that can be closed off (i.e. bedrooms, offices)

When air leaks out into the attic or outdoors, a corresponding amount of air is drawn in from the attic and outdoors, so yes you may be drawing in cellulose or dust from the attic because of the lack of proper ducting and damaged ducts. While the ideal house and air conditioning system is a "closed" system, in reality, neither is truly a closed system because of imperfect ducts and building envelope.

Originally Posted by Phil Marlino

Thanks again for the replies.

Raymond, my wife's problems are much more pronounced in the Summer; we have 3 CO detectors in the house and we regularly service the units. Her condition is something allergy like (dizziness, morphing sometimes into vertigo, no headaches).

Ductwork concerns aside, with the dizziness and vertigo, she might want to see a cardiologist right away. In 2009, my wife had an attack of severe vertigo/dizziness and I called 911. It was a transient ischemic attack (TIA), mini strokes. A year later, when she just sat still and did not respond, I called 911 again and she was rushed to the hospital with a massive ischemic stroke. Fortunately, she has mostly recovered.

Allergies generally do not cause vertigo or dizziness. However, moving from one area to another means that different allergens are present so visiting an allergist might be worthwhile.

Originally Posted by Ted Thompson

Ductwork concerns aside, with the dizziness and vertigo, she might want to see a cardiologist right away. In 2009, my wife had an attack of severe vertigo/dizziness and I called 911. It was a transient ischemic attack (TIA), mini strokes. A year later, when she just sat still and did not respond, I called 911 again and she was rushed to the hospital with a massive ischemic stroke. Fortunately, she has mostly recovered.

Allergies generally do not cause vertigo or dizziness. However, moving from one area to another means that different allergens are present so visiting an allergist might be worthwhile.

I had not read down the discussion far enough and missed the electronic air cleaners comment..

Check out the EPA’s take on electronic air filters:
Guide to Air Cleaners in the Home | Indoor Air | US Environmental Protection Agency

They state:
“Electronic air cleaners such as electrostatic precipitators use a process called electrostatic attraction to trap charged particles. They draw air through an ionization section where particles obtain an electrical charge. The charged particles then accumulate on a series of flat plates called a collector that is oppositely charged. Ion generators, or ionizers, disperse charged ions into the air, similar to the electronic air cleaners but without a collector. These ions attach to airborne particles, giving them a charge so that they attach to nearby surfaces such as walls or furniture, or attach to one another and settle faster.

Then the Catch 22: Ozone is a lung irritant that can cause adverse health effects.

I suspect that others here on the forum can suggest non-electronic air filters/cleaners that won’t cause health problems.