Table of Contents
How far should you run flex duct?
Flexible duct shall be supported at manufacturer’s recommended intervals, but at no greater distance than four feet. Maximum permissible sag is 1/2 inch per foot of spacing between supports.
Does Flex duct reduce airflow?
Friction is the enemy of airflow. Unlike rigid ducts, which are cut to length within a tolerance of 1 inch or less, it’s easy to cut a length of flexible duct that’s several feet longer than is needed to get from point A to point B [2A]. That creates slack in the duct, which reduces airflow for two reasons.
Should I replace metal duct with flexible?
Flex ducts are better for existing trunk-and-branch heating and cooling systems. Metal ducts are more rigid due to the nature of steel, making them ideal to build an entire HVAC system. Installation. In comparison to metal duct, flex duct is easier and faster to install.
Can flex duct be used for return air?
Flex duct is widely used for return air in commercial air conditioning systems. Flex duct is able to withstand a certain negative pressure of return air. When installed properly, a flex duct is a reliable and convenient ductwork solution. Flex duct often gets a bad rep because of airflow issues.
Can I use flex duct to vent range hood?
No. Avoid flexible duct for your range hood, regardless of the CFM. Flexible duct is a poor investment because it is: Not durable/sturdy.
How do you insulate a flex duct?
How to Seal and Insulate Flex Duct at a Collar Connection Pull the end of the flex duct over the end of the collar, pulling the flex duct core at least 2 inches past the raised bead. Push back the outer liner and insulation. Wrap the nylon draw band around the duct over the inner liner, above the raised bead.
How do I know what size flex duct I need?
Measure the length and width of the room where the flex duct will be supplying the air. Multiply the length and width together to get the square footage of the room. For example, a 10-by-10 room will be 100 square feet.
Do you need clamps for dryer vent?
When installing a vent between the dryer and the vent cap, we usually need to use s clamps to hold the pipe to the fittings. When you screw metal pipes together, the screws might become clogged with lint over time and cause issues. Using the Phillips-head screwdriver, tighten the screw until the clamp is secure.
Can you use flex duct in crawlspace?
Flex duct is commonly used in crawl spaces. That said it is vulnerable to punctures, animals and other hazards. Animals have no particular reason the chew the ducts, but sometimes they will anyway. Flex duct is cheaper to install than hard duct, and (at least initially) it is easier to make it not leak.
How do you attach duct to vent?
Attaching HVAC Ducts Push the ducts together firmly. Insert 1/2-inch self-tapping sheet metal screws through metal ducts where the ends come together. Staple fiberglass ducts together with a staple gun and 1/2-inch staples. Attach flexible HVAC ducts with plastic or metal duct bands or straps.
Can I add a vent to existing ductwork?
Yes, it’s quite possible to add a vent into the existing ductwork. But, you’ll need to check the compatibility of the AC and heater. After this, locate spots and mark them. Then, cut the piece and add the vent cover after ensuring the right fit.
What is the disadvantage of flex duct?
The downside of flex ducting is that it is considered temporary with an acknowledged lifespan of only about 15 years. Another major disadvantage is that they are a little too flexible, so they are often incorrectly installed. And with greater friction than metal ducts, proper sizing is critical.
Should flex duct be pulled tight?
Flex duct should pulled tight to reduce inner air resistance. It should be supported with straps that are a minimum 1.5″ wide. The straps need to be spaced no further than 5 feet apart, but closer is better. Local codes or manufacturers instructions may specify shorter intervals.
Can you squish flex duct?
Because flex duct is so flexible, contractors are sometimes tempted to bend it too much or squeeze it through areas that are too narrow. These compressions can greatly restrict air flow, hindering HVAC system performance and leading to comfort complaints from homeowners.
Are flexible ducts good?
Pros of Flexbile Ductwork Flexible ducts are cheaper than metal ones. This can save you money on installation and upkeep. That means they can be installed in tight spaces where traditional metal ducts wouldn’t fit. If you’ve got sharp corners and lots of angles, flexible ductwork is a good option.
When hanging flexible duct the hanging material should be at least?
When hanging flexible duct, the hanging material should be at least: 2 inches wide and spaced no further than every 5 feet.
Can I use flex duct for dryer?
All dryer ducting must be a minimum of 4″ in diameter. Flexible transition hose between the dryer and the wall outlet should be either the foil type or the aluminum flexible duct (most preferred). Do not use the plastic or vinyl. Concealed ducting must be rigid metal (galvanized or aluminum) duct.
Can you have too many air returns?
Having several return vents (ideally one in every room, but even two or three is better than just one) creates consistent air pressure. If you have one return vent, your home is fine. Keep the doors to each room open so air can properly circulate.
What size duct do I need for a 12×12 room?
A 12×12 foot room will need a 4×8 inch supply duct to get an adequate CFM rate, which is about 144 CFM.
