Insulation Between Ac Ducts In The Attic

Why is this a problem.

Insulation between ac ducts in the attic.

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. 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. When water condenses and drips into your attic or home it can cause a some serious secondary problems.

To insulate the exterior you have a choice between sleeve style insulation and blanket wraps which literally wrap around the ductwork. 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. If the air distribution is in the attic space then consider insulating the rafters to move the distribution into the conditioned space. Attics are for the most part unconditioned meaning a leak here could significantly reduce your home s overall efficiency.

The flex ducts were literally filled shut with ice in the low spots compressing the scant insulation layer beneath them. Put it in an attic full of blown insulation and you re forcing. The existing metal ductwork in an older home may or may not have insulation. So water is condensing on your ac ducts.

The condenser in your air conditioner works hard to get rid of heat and pressurize refrigerant for the return trip through your house. But even if the ducts are installed to a tee there s still the possibility that leaks will develop. 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. The rigid insulation was saturated from condensation.

The number one prep step. The residential acm manual states that ducts shall have a minimum insulation value of r 4 2 prior to burial. In unfinished attic spaces insulate between and over the floor joists to seal off living spaces below. 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.

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. Have you ever considered the temperature differences delta ts across those different insulated surfaces. 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. Other times insulation may be on the outside.