How to deal with ductwork that is installed in an unconditioned attic and a powered attic ventilator?
I am a homeowner of a brick ranch built in 1960s in Climate Zone 7, and it is about 1,800 sq. ft. [Editor’s note: It turns out that Ted is really in Climate Zone 4.]
The previous owner had the furnace and ductwork were installed in the attic and a powered attic ventilator (PAV) too in 2013. The attic floor does have some fiberglass as insulation material and it is about 8 inches. The ductwork is insulated flexible duct (supply duct is black from the outside and the return duct is silver from the outside).
In hot days last week (about 95F outdoor), the attic was over 120F and the PAV was running (thermostat of PAV set at 120F). All the ductwork were warm from the outside so I think the hot attic reduced the efficiency of the A/C (also newly installed in 2013).
In hot days, the indoor temperature was about 76F but not able to go blow it when attic was hot. I read lots of useful articles on this website and in general, it seems the PAV and the radiant barrier are not recommended. I am not sure if the general talk also applied to my situation.
Should I turn off the PAV so it won’t suck cool air from the conditioned area? I see vent of the gable and I can see daylight come in on two edges of the roof so I think they are for outdoor air to come in to the attic.
Should I put more insulation material on top of the attic floor and the ductwork? Will radiant barrier under the rafters help?
Thanks in advanced for your comments and recommendations.