What do we know about (house) air duct cleaning?

Mine aren't clean. Is this a DIY with some future hammers from HF? Are the "too good to be true" Groupons pure bulkE36 M3?
 

Educate me please. 

We had someone come in and do it in our 100yr old house in 2019. They had to drill holes in all the feeds/returns, to get the "whip-things" in. Definitely improved peace of mind, not sure it improved anything else.

In reply to OHSCrifle :

No. 
 

It's so simple to hire and low cost, I see no point in trying to DIY it. 
 

Call a local HVAC contractor. 
 

They should bring a very large 220V blower fan, and seal it via ducting to the return air duct. They will blow the air to the outside, filtering through a HEPA vac. Then they will shove brushes into all the supply ducts and scrub. 
 

It will pull out a LOT of crap, cost a couple hundred dollars, be done in a couple hours, and not mess up your house. 
 

DIY isn't worth it. 

How accessible is your ductwork?  How old?   Is it all sheet metal (smooth inside) or duct board (rougher coated fiberglass)?  The return air duct is typically the worst from my experience.   Vacuum out the return boots (the short ducts that connect to the main) for starters.   If you can reach up the return near the furnace with the vacuum that helps too.   If you’re maintaining your air filters the supply duct shouldn’t be that dirty.  

If you can get to the duct mains (exposed in the basement for example) you can cut in access points and vacuum it out and then patch them and seal them, not super high tech but it’s basically what the cleaners will do.   When it’s not accessible, then it’s more complicated.  The cleaning companies will usually disconnect the duct at the furnace and install a large vacuum or negative pressure fan with filtration to the duct and then used motorized brushes on a wire snake to loosen the dirt and debris so it goes down the duct and gets trapped in the machine.   Sheet metal being smooth is pretty easy to clean   Ductboard is rough and so it tends to hold dirt.  It’s also easy to damage and can fall apart if the sealant tape has dried out.  (Ductboard sucks!) 

Not so much a residential situation but in the commercial world we often get the “The ceiling grilles and ceiling tiles are dirty, we need the ducts cleaned!!!”  In reality the dirt is from the room, carpets, etc. in the space.  The way the diffusers work is by pulling room air up and mixing it with the supply air from the HVAC system, the dirt gets pulled up with the room air end some ends up on the grille and ceiling tiles near it.   It’s called the coanda effect, a search will describe it better than I can.   

TLDR, if your office HVAC grilles are grody your cleaners probably suck.  Also cool extra points science word for y’all.  No quizzes later.  

Thanks guys. I've got all ductwork visible in the basement so it should be about as easy as it gets for a company that knows what they're doing. Metal duct except the last 3-4' is very old flex. 

Just to highjack a smidge, my A/C system just has the flexible insulated duct work in it.  Any reason I shouldn't just replace them all instead of cleaning?  They're old and I already replaced one section because it was leaking.  Seemed pretty easy. Just thinking I could kill two birds with one stone and get clean and new ducts with better insulation.

-Rob

In reply to rob_lewis :

I like that idea. If I hadn't painted all my ductwork along with the joists and floor sheathing, replacement of the flex runs would be a no brainer. I might do it anyway. 

In reply to rob_lewis :

Replace it, it’s nearly impossible to clean properly. 

Edit: Try to pull it as straight as you can, no kinks!  The wire inside the Mylar inner liner acts like a slinky and the Mylar will accordion and create a lot of resistance to airflow if it’s not pulled out.   We try to keep it to the last 3 to 5 feet from the sheet metal to the grilles.  

What I know about air duct cleaning, and it doesn't help the OP in the slightest, is that the entire industry in the Greater Toronto Area seems to be controlled by one company that uses a very diligent telemarketing firm in India or Pakistan.  Their people call us several times a month.  They cannot understand that this house has not had a single air duct in it since it was built, which was during the Reagan administration.

THIS IS COPIED DIRECTLY FROM THE EPA WEBSITE:

Duct cleaning has never been shown to actually prevent health problems. Neither do studies conclusively demonstrate that particle (e.g., dust) levels in homes increase because of dirty air ducts. This is because much of the dirt in air ducts adheres to duct surfaces and does not necessarily enter the living space.

Stealthtercel said:

What I know about air duct cleaning, and it doesn't help the OP in the slightest, is that the entire industry in the Greater Toronto Area seems to be controlled by one company that uses a very diligent telemarketing firm in India or Pakistan.  Their people call us several times a month.  They cannot understand that this house has not had a single air duct in it since it was built, which was during the Reagan administration.

Also around here the duct cleaning is done with a giant van-mounted vacuum cleaner (since houses typically have metal ducting, miniature versions of the ones you can crawl around in) and when one of these is powered on, it rattles the whole neighborhood. I imagine the house being cleaned is completely uninhabitable while this is going on.

carguy123 said:

THIS IS COPIED DIRECTLY FROM THE EPA WEBSITE:

Duct cleaning has never been shown to actually prevent health problems. Neither do studies conclusively demonstrate that particle (e.g., dust) levels in homes increase because of dirty air ducts. This is because much of the dirt in air ducts adheres to duct surfaces and does not necessarily enter the living space.

 

 

Umm...

You realize no one mentioned health problems?

I just wanted mine clean. 
 

Plus, I was battling the smell from the previous owner who was a heavy smoker, and cleaning the ducts DID help with that. 
 

Part of the duct cleaning was also cleaning the coils, and I did see a noticeable improvement in efficiency. 

In reply to 11GTCS :

Cool! I did not previously know that "grody" was a science word...

In reply to Stealthtercel :

These guys call me at least one a week. I politely tell the nice Indian accented gentleman that we only have cats and no ducks but thanks for calling! 

House is hot water heat, so no ducts either.

SV reX said:

In reply to OHSCrifle :

No. 
 

It's so simple to hire and low cost, I see no point in trying to DIY it. 
 

Call a local HVAC contractor. 
 

They should bring a very large 220V blower fan, and seal it via ducting to the return air duct. They will blow the air to the outside, filtering through a HEPA vac. Then they will shove brushes into all the supply ducts and scrub. 
 

It will pull out a LOT of crap, cost a couple hundred dollars, be done in a couple hours, and not mess up your house. 
 

DIY isn't worth it. 

This. I had it done about 12 months after I bought my house (which was 4.5 years ago), because it previously had had smoke damage. Also had them do the dryer duct at the same time.

Just had them do the dryer duct again since it's a convulted design, thanks to not being on an outside wall. So it runs up the inside wall, 90 degree turn in the attic about 7-8 feet through the attic, another 90 degree turn to dump on the bottom side of the eve on the front of the house.