Insulation Between Ac Ducts In The Attic

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.

Insulation between ac ducts in the attic.

The duct work is insulated to keep the condensate from forming on the outside of the pipes and dripping off from the temperature differences in the attic in the summertime with ac running. In more cases than not a 3 ton ac with the ducts in the attic has a ton or so of load that s just from the location of the ducts in the attic and the associated duct gains leakage etc. Why is this a problem. Our heating and ac ducts are 100 within the thermal envelope in the floor trusses above our insulated basement.

Well mainly it s a way to save space. What would be bad is if the duct work is flex duct and gets mashed under the weight of the added insulation on top of it. Why is condensation on ductwork a problem. 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.

2 duct leakage must be no higher than 1 5 cfm25 per 100 square feet of conditioned floor area. So why put an hvac system up in the attic at all. 1 the air handler must be inside conditioned space. In last week s blog i discussed the practice of burying attic ducts in deep insulation since burying ducts is simply one of several ways to address the energy waste associated with the decision to locate ducts in a vented unconditioned attic it s worth taking a fresh look at all of the possible solutions to the attic duct problem.

Other times insulation may be on the outside. Attic hvac systems save space. So more would help. Sometimes the insulation is inside the ductwork.

The condenser in your air conditioner works hard to get rid of heat and pressurize refrigerant for the return trip through your house. Flexible ductwork comes with different insulation r values. So water is condensing on your ac ducts. Most updated central air conditioned homes have a new air conditioner split system meaning the ac is broken up into parts.

And 3 the sum of the ceiling insulation above the duct and the duct insulation must equal the prescriptive r value for ceiling insulation. The remaining 2 tons of capacity is at least 1 5x oversized for the actual 1 load. But our erv ducts stand alone system not tied in w heat pump and 2 jumper ducts for pressure balancing from bedrooms are suspended above the insulation in our vented attic. The second question gets a yes if the buried ducts meet even more stringent requirements.

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