This is one, if not the most controversial subject in the HVAC industry over the last 5 years and it shouldn't be. What do I do with my existing ducts? What are the best kind of ducts? Should I have my ducts cleaned?
Most homes built between 1924 and 1980 used metal tin or galvanized ducts with
either fiberglass or aircel insulation. If the ducts are 5" round for bathrooms, 6"
and larger around the rest of the home and have not been molested? Use them.
You have one of the best duct systems. It will require additional work to make
them ready for high efficient air conditioning but well worth the trouble and the
additional cost. This additional work will include but not limited to:
Check all ducts for tight joints, screw secure and seal air tight as needed. Reinsulate ducts with thick fiberglass duct wrap to retain temperature. If missing, install locking type dampers to regulate air flow into each area.
This work will takes two professionals about a day to perform. There is nothing fast about crawling in an attic or crawl space. When wrapped properly, the insulation around the ducts is pulled very tight. No sags or air gaps. Now what you'll have is a duct system that will last almost forever, rodents will never eat through, superior air flow, even temperature and something difficult to crush.
What kind of Ducts are Best?
Well this is where you're going to get a different opinion with each air conditioning and heating
contractor. But there is only one right answer. Metal Insulated Ducts.
Most contractors will try to convince you that their plastic mylar flex ducts are much better that your old metal ducts. Wrong, Very wrong. There is nothing good about flex ducts for the exception that they are cheap and easy to install. The only reason other contractors use them is because they are the same cost or cheaper than the additional work to make your existing metal ducts ready for high efficient air conditioning. The best ducts are metal ducts hands down. Here are the reasons for not using FLEX DUCTS:
Flex ducts are like a slinky, not self supporting, sag, easily torn, easy to crush, very easy to kink and easy to install wrong.
Flex ducts provide very poor air flow compared to metal ducts.
Flex ducts fall a part in a few short years. They are temporary ducts.
Flex ducts promote mold growth on the inner plastic core.
Unless you purchase the very expensive microbial flex duct. Then you have more than enough $$ to purchase metal ducts. Rodents can and will eat into flex ducts. They defecate and urinate on the inside of the ducts. That should smell real nice? Flex ducts off gas. Some people can smell the plastic inner layer. Check on line. But what you'll hear from other contractors is: "We've never had a problem with our flex ducts". Oh yeah! Just look at the pictures below. We change out flex ducts to metal insulated ducts almost every day! Even the super duper R-8 mylar flex ducts.
OK, I know what you're thinking. "Wow, metal ducts must be expensive". No, not really. Its only
additional labor it takes to install the metal ducts and with our trained professional installers we can
install metal insulated ducts for only a few hundred dollars more per system than flex ducts.
Why don't other contractor's use them? Most contractors don't know how to install metal ducts. It is difficult for untrained personnel to install them right. Ask other contractors for a quote on using metal insulated ducts and wait for all the excuses why they won't quote you. The real fact is they don't know how and it will take them way too long to complete the job after they fumble around. They want quick and easy. Get in, get out.
If you replace an entire duct system it will add about 1 to 1-1/2 days labor. Thats $400 to $600 more cost to the job cost than plastic flex ducts. A real bargain considering with plastic Mylar flex duct you will be replacing flex ducts every 7 to 10 years. If the rats don't eat though them first! Why METAL DUCTS are superior: Metal ducts are self supporting and don't sag or fall between joists. Metal ducts increase air flow by 30% to 40% more compared to plastic flex ducts. That is air which will heat and cool your home or business much faster. Metal ducts will last almost forever if you don't jump on them. Rodents will not eat into metal ducts. If they ever do, we're all in big trouble! Mold will not grow in metal duct work. Metal ducts don't off gas like the inner plastic core of flex duct. Some people can smell it? They cost a little more money but well worth it. Just a note, that there are some circumstances where it will be necessary to install an acoustical sound baffling duct section into some short metal ducts to attenuate noise. This is covered in a proper ACCA Manual D duct installation instructions. We always follow manufacturers specifications, warranty provisions and local codes.
Every week we all get the same Post Card in the mail for "Duct Cleaning" that shows the nastiest
rectangular "Before and After" duct cleaning you ever wanted to see. With the words "If its in
your ducts, its in your lungs". OK, we have installed tens of thousands of heating and air
conditioning systems using existing ducts and I have looked down inside these ducts and never,
ever, ever have I found a duct system that even looks close to the one in the picture that
everyone gets in the mail. The fact is most filth for an entire duct system can fit the size of a
quarter in the palm of your hand. There are only two areas that can get filth to stick to the walls
of a duct system. Grease ducts from a kitchen and extreme smokers where the nicotine gets
sucked into the return duct and makes it sticky. I have seen Mobile home floor ducts leak and
draw in filth from under the house and it's bad but nothing like that picture. And of course a
Dryer duct. But you don't breath in that air. I think every duct cleaning company uses the same
The problem is you never looked inside your ducts so you think "wow they must be filthy, I never had them cleaned" you just assume. We now have this cool tool. Its a camera with a wand that we can stick up into a duct system for the owners to examine and see first hand whats really in their ducts. Pretty much nothing. Don't waste your money on duct cleaning. Check and see whats inside your ducts first before you spend any dollars for this service unless you're hyper sensitive?
I have seen more damaged ducts from duct cleaning companies than the cleaning was worth.