Attic Ductwork R Value

Insulation levels are specified by r value.

Attic ductwork r value.

So i notice the ductboard is oc s quietr with an r value of 4 3. My attic gets hot and so i was wondering how much cool air i was losing to the heat of the attic. The effective r value of a buried duct installation depends on the size of the ducts the r value of the duct insulation and the depth of the loose fill insulation. When insulating ducts understanding the meaning and impact of r values and insulation thicknesses is essential to getting the most efficient affordable outcome on your heating installation project the ratings provide a guide for homeowners that determines the effectiveness of the insulation making it easier to choose the right insulation for your home.

For example if you have a type of insulation that has an r value of r 5 per inch of thickness you will need a depth of 6 inches of this insulation installed in your attic to reach r 30 if you live in zones 2 or 3. The higher the r value the better the thermal performance of the insulation. Return ducts ductwork that brings expended air back to the hvac system to be filtered reconditioned and redistributed require insulation with an r value of 3 5 for exterior ducts and ducts in a ventilated attic or unvented attic above an insulated ceiling. It was new when the ac was put in 7 years ago.

Table 1 shows effective r values for 8 inch round ducts at three attic insulation levels and three duct insulation levels r 4 2 r 6 and r 8. I called out the original hvac company and they took a look and said they saw no water. Recommended home insulation r values. Add the right kind of insulation.

When comparing r value between duct and attic insulation you have to consider the the air is moving through the duct and is already conditioned so it is picking up minimal heat from the attic air. Since the installation is in an unconditioned attic space i went up and looked at the duct install. This is why the r values are so different. The attic ductwork is flex duct work.

Allison bailes of decatur georgia is a speaker writer building science consultant and the author of the energy vanguard blog. The recommended level for most attics is to insulate to r 38 or about 10 to 14 inches depending on insulation type. I check on the oc website and find that the 4 3 is the lowest r value they make. R value is a measure of insulation s ability to resist heat flow.

And that means it s time to deal with duct insulation in a more meaningful way than just increasing the required r value to 8 for ducts in attics. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation. If you measure air temp at evaporator coil and supply air temp from vents the air is picking up very. Recently i had another hvac company come out and put in a new bathroom vent and they told me they believed the duct work was full of water.