I have noticed similar behavior with water. And I wonder, since ducts all have the same starting pressure and ending pressure, if you were to run parallel groupings of smaller pipe multiple outlets in the same room , if the amount of resistance from blower motor to room would drop?
That would also lower the amount of pressure the blower would have to surpass to move the air. I also wonder if other I also wonder if other materials can be used for ductwork.
In caustic environments, cpvc pipe is used. In the power industry, High Density Poly Ethelene hdpe pipe is used. They do make a low smoke version for use in confined spaces like electrical vaults and substation basements. The reason why I am looking for something besides sheet metal pipe is 1 plastic is a much better insulator and therefore less heat is loss through convection of the duct itself. Sure, you can insulate a sheet metal duct, but why not buy a pipe where that is not necessary?
Another reason is the smoothness of a plastic pipe is better than even galvanized steel, which would then be better to reduce the turbulence mentioned in the article. And because it is a better insulator, there is less sound produced within the pipe than there is in typical sheet metal duct. A third reason is that plastic pipe can be made stronger than sheet metal.
Much lower rates of dents that occur in transit or installation. A fourth reason is that proper installation requires the pipe to be either fused together or joined by some sort of adhesive. This makes it air and water tight. No additional sealing required think duct tape that is used with sheet metal duct , which would make for easier and quicker installation.
I understand the two prevailing thoughts against using plastic pipes are the flammability and smoke specs. However, plastic pipes have been made to follow these standards. Plastic pipe is also used in water systems, even hot water boiling systems…where the water temp is hotter than any residential plenum should ever get.
Hey Allison, Hey Allison, thanks for posting this informative article but I am confused by these statements you made:. Fred, yes, it would absolutely be better for air flow to shorten that duct. A lot of poor air flow problems in ducts are on the return side so anything you can do there to fix it should result in noticeable improvement.
There are times where flex duct or sections of it can help to reduce costs. The only way to secure them consistently is to use a tensioning tool. These use a ratcheting mechanism to fully tighten the tie, and then cut it flush. No slipping — ever. They are required tools for all of our installers required to have them AND to use them. I salute you sir, I salute you sir, Over the years, I have seen remarkable things on construction sites…major load carrying wood beams cut nearly in half to accommodate ductwork and my favorite…the ductwork seems to be the easiest place to throw trash, construction waste and even concrete.
If you are a brave soul, if you ever get the chance, use one of the television camera snakes to explore what is in the ductwork of many homes and commercial buildings. What is the estimated life of What is the estimated life of zip ties? We are also in the Pacific NW and 1 most of our duct systems are in crawl spaces, not attics, and 2 our temperatures are fairly mild.
You can even use three sheet metal screws behind the first rib or two of the duct, as long as you use mastic under the duct at the sheet metal connection. The plastic zip ties zipped tight with the tensioner seems like the way to go.
When the latest 3rd edition When the latest 3rd edition of Manual D was in development, there was a lot of discussion about friction rates of poorly installed flex. I should point out that the ADC lobbied heavily to keep this data out of the book, but in the end, the data was included as Appendix Adam G.
David R. See the photo I recently shared on our Facebook page facebook. This will ensure that you have a good surface to reapply new tape to. Just clean off any debris and tape over the old tape. This issue is worse with the high-efficiency systems, which run at a lower capacity for longer. So make sure to seal your joints with mastic gum or a metal-backed tape will also prevent leaks.
Once your ductwork is in place run a final check. Get your HVAC unit to check that airflow levels are right. Some of the latest models will offer app-controlled air-con settings. This helps save installers time on site. They can use the app to check that airflow levels are correct. This removes the issue of having to go back to the control unit to adjust fan speeds manually.
In turn, this ensures accurate commissioning. You want to make sure everything works at full capacity on installation. If not, you might face a costly call back to fix any issues. During an HVAC ductwork installation, you need a company that knows how to properly size duct so that is can carry the air throughout the entire length of your home. During an air duct installation depending on the type of materials that you are using, you are going to have to insulate the duct. For instance, if during an air duct installation you are using a metal pipe or metal rectangle duct, you are going to need to insulate it.
However, there are some situations in which the duct might require more insulation. For instance, if you are installing the duct in a crawl space or basement the metal is going to require more insulation.
However, if you are installing the metal duct in an attic or insulated space it will not require as much insulation. Here at Pure Airways our techs are trained and certified in installing ductwork in a variety of different situation.
This is especially true if you are installing the ductwork in a crawlspace. If the crawl space is not properly sealed then critters and squirrels will be able to get in and tear up the ductwork. However, with properly hung ductwork these critters will not be able to get duct.
However, while hanging ductwork might seem like an easy task it is not.
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