Should the plenum be insulated?

Asked By: Nikte Levitz | Last Updated: 16th January, 2020
Category: home and garden indoor environmental quality
3.9/5 (157 Views . 41 Votes)
Ducts are made of sheet metal, fiberglass, or other materials. Ducts that leak heated air into unheated spaces can add hundreds of dollars a year to your heating and cooling bills, but you can reduce that loss by sealing and insulating your ducts. Insulating ducts in unconditioned spaces is usually very cost-effective.

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Besides, does ductwork need to be insulated?

Insulation is applied to ductwork to enhance thermal performance and prevent condensation and dripping. Return air ducts only need to be insulated if they pass through environments that adversely affect the return air temperature. Exhaust air ducts normally do not need insulation.

Likewise, what is the best duct insulation? The fiberglass duct board is by far the most effective. You can find formaldehyde-free insulation that also has an acrylic coating. This coating will help to keep the glass fibers from your airstream and excess noise from your home. You will also be able to enjoy a higher air quality.

Besides, what is insulated ducting used for?

Insulating ducts in unconditioned areas of the home can help reduce space heating and cooling energy costs and improve indoor comfort. In humid climates, properly installed duct insulation can also reduce moisture condensation on metal ducts.

What is the best material for ductwork?

Galvanized steel and aluminum are the most common materials for sheet metal ducts. Aluminum in particular is relatively light and easy to install. They are also the least likely to harbor dangerous molds or growths because they have non-porous surfaces.

33 Related Question Answers Found

How can I hide my HVAC ducts in my basement?

  1. Paint. The fastest and least expensive way to cover your duct work is to paint it the same color as your ceiling.
  2. Soffits. Soffits, also called bulkheads, are a frame you build around the duct work to hide it from view.
  3. Drop Ceiling.
  4. Flattened Ducts.

How do you seal HVAC ducts?

Duct joints should always be secured with #8 sheet-metal screws before seams are sealed with mastic. Sealing duct seams is messy work, so wear old clothes. The mastic is spread over duct seams with a disposable paintbrush, putty knife, or your fingers. (If you spread mastic with your fingers, wear rubber gloves.)

Can you insulate around heating ducts?

Air ducts typically are not insulated, creating costly heating and cooling losses. You can insulate the round air ducts serving your rooms with standard insulation batts or special-purpose duct insulation. Insulating your air ducts can save 10 percent to 30 percent on energy bills while improving comfort.

How much does it cost to insulate ductwork?


The average duct insulation cost will be between $0.95 and $2.00 per sq. ft. installed, the cost will vary depending on a few factors which are discussed below, however r-values have the biggest impact and unsurprisingly insulation with r-values of r-3.5 are the cheaper, up to r-8.0 for the most costly.

How many square feet will a 3 ton AC cool?

METHOD 2: Go by square feet + climate
HVAC System Sizing
Blue Green
2.5 tons 1401-1650 sf 1351-1600 sf
3 tons 1651-2100 sf 1601-2000 sf
3.5 tons 2101-2300 sf 2001-2250 sf

What is an HVAC plenum?

Supply Plenum
A plenum is an air-distribution box attached directly to the supply outlet of the HVAC equipment that heats or cools the air to make the house comfortable. The ductwork that distributes the heated or cooled air to individual rooms of the house connects to the plenum.

How do you insulate a furnace?

Insulating the walls and ceiling in a furnace room can reduce heating costs and make the furnace more energy-efficient. Rigid foam insulation is attached to the walls with adhesive, and to the ceiling with adhesive and roofing nails.

How do you insulate attic ductwork?

Sometimes a foil-faced blanket is wrapped around the duct. In other cases, a duct run can be insulated with spray foam. A third option (with attic ductwork) is to add enough extra attic insulation so that the ducts are completely covered with the new insulation.

How do you insulate HVAC pipes?


Measure the A/C line diameter and order the insulation
Wipe off the condensation and wrap a few winds of the sticky poly tape on the tubing where it exits the house. Then dry and wrap the service valve on the condenser end of the tubing. Squeeze it in tight around the tubing.

Can you use flex duct return air?

Re: Flex Duct on Return Air Diffusers - Yes or No? Flex duct effectively creates a tight radius elbow where it turns into the top of a diffuser. The high pressure loss is further increased because the flex fabric gathers at the inside of the throat and reduces the effective diameter.

Do I need insulated duct for bathroom fan?

If bath fan ducting isn't properly insulated, the moist air from your house will condense inside the duct. The first step is to head to the attic. You may find that the insulation simply needs to be refastened. If your ducts are properly insulated, another potential cause of condensation is lack of use.

What is the R value of flex duct?

For example, a six-inch diameter, nominal R-8 flex duct has an actual R-value of only 5.62 not counting surface films. With the film resistances the total R-value of 6.45 is 19% less than the nominal value. For R-11 ducts (six-inch diameter) the R-value with films is only 7.81, 29% less than the nominal value.

Is insulating ductwork worth it?

Ducts are made of sheet metal, fiberglass, or other materials. Ducts that leak heated air into unheated spaces can add hundreds of dollars a year to your heating and cooling bills, but you can reduce that loss by sealing and insulating your ducts. Insulating ducts in unconditioned spaces is usually very cost-effective.

Is bubblewrap a good insulator?


Bubble wrap is an excellent insulator thanks to small pockets of air trapped within the bubbles. After applying bubble wrap insulation to your windowpane from the inside, tiny bubbles serve as a network of many insulating pockets filled with air.

How do you increase airflow in ductwork?

3 Simple Ways to Improve Your Furnace's Airflow for More Comfort
  1. Unblock and clean your vents. Here's a super easy way to increase air flow.
  2. Change your filters and clean your return grill. A dirty air filter impedes air movement and makes it hard for your furnace to work efficiently.
  3. Seal leaky ductwork. Snap on some goggles and a dust mask, it's time to check out your air ducts.