Insulation Between Ac Ducts In The Attic

If we put ducts in unconditioned space they have to be insulated to either r 8 if they re in an unconditioned attic or r 6 in any other type of unconditioned space.

Insulation between ac ducts in the attic.

The number one prep step. To avoid this hvac contractors must take care to properly seal and insulate air ducts something not all of them do to the same degree of precision. So water is condensing on your ac ducts. But even if the ducts are installed to a tee there s still the possibility that leaks will develop.

To insulate the exterior you have a choice between sleeve style insulation and blanket wraps which literally wrap around the ductwork. Gaps in the attic or between the lower floors and the attic will let heated or cooled air escape to the great unconditioned outdoors making any insulation you add essentially useless. I found instead a vintage 3 ton ac unit with 1 rigid insulation taped all over it and insulated flex duct snaking all over the poorly insulated attic. Sometimes the insulation is inside the ductwork.

Why is this a problem. Attics are for the most part unconditioned meaning a leak here could significantly reduce your home s overall efficiency. The rigid insulation was saturated from condensation. Because the moving air is in the ductwork for only a short period of time it does not need the insulation r value the attic floor requires.

Find a diagram of common air leaks here here s a quick primer on fixing draft prone spots. The acm manual also provides tables for effective r value of buried ducts based on attic insulation level and nominal duct diameter. 1a attic access door. The condenser in your air conditioner works hard to get rid of heat and pressurize refrigerant for the return trip through your house.

When water condenses and drips into your attic or home it can cause a some serious secondary problems. To install sleeves you must either disassemble the ductwork and slide it on before reassembling the ducts or as many homeowners find themselves doing slit it and wrap it around like the blanket style material. First water dripping off of your ducts and onto your insulation can cause the insulation to compress which decreases it s r value or ability to insulate. The flex ducts were literally filled shut with ice in the low spots compressing the scant insulation layer beneath them.

The residential acm manual states that ducts shall have a minimum insulation value of r 4 2 prior to burial. If the air distribution is in the attic space then consider insulating the rafters to move the distribution into the conditioned space. Other times insulation may be on the outside. In unfinished attic spaces insulate between and over the floor joists to seal off living spaces below.