The air handler unit on my central air conditioning system in Florida is located in a closet that opens to the attic. The air handler is exposed to the attic temperatures (hot) which seems counter intuitive for maximum cooling capability. The cooling coils are bolted to a metal frame that's as hot as the attic.

Should I insulate the closet so the majority of the indoor unit is, truly in cooled indoor space?

What are the pros and cons of my current (typical) setup versus an indoor air handler that resides in the cooled space?

  • Are your ducts in said vented attic as well? Jun 7, 2020 at 17:54
  • Do you have a strip heater in the air handler? Is there one main return?
    – JACK
    Jun 7, 2020 at 18:00
  • yes to both. Ducts are insulated from top of air handler to each room via attic. There is only 1 return air intake located immediately below the air handler. Indoor air returns through intake vent near floor then goes vertically through air handler, across cooling coils, out the top into cooling ducts. Jun 7, 2020 at 19:41
  • @MarcCompere -- how much insulation is around the ducts? Jun 7, 2020 at 20:18
  • I've got standard insulated air ducts. Some 4-inch. Some 6-inch with plenty of pink and older style dark grey fiberglass insulation on the tops of the rooms Jun 9, 2020 at 0:19

1 Answer 1


This is the same arrangement as in all 270 houses in my tract development in Dallas TX. It is the standard arrangement. There is some insulation on the inside of the sheetmetal panels.

EDIT Given the new info that this is a heat pump it would be some benefit to put an insulated ceiling on the closet. Possibly the original heating was a gas fired furnace and the heat pump a retrofit.

EDIT2 If there is a gas fired water heater in this closet,then it is probably necessary to have an opening for combustion air or to expel heat to the attic.

EDIT3 Our closet has an insulated drywall ceiling with one small section of screening to supply combustion air from the attic to the gas fired furnace and the gas fired water heater.

  • leave it alone is not a useful answer. it seems that an HVAC unit would deliver more cooling to the air if it didn't have to cool the metal frame exposed to hot attic temperatures Jun 9, 2020 at 0:19
  • Do you have a gas furnace in the same unit? If so, does it get its combustion air from the closet or from outside? Jun 9, 2020 at 15:19
  • In Dallas TX many houses have the air handler with refrigeration coils in the attic, not just in a closet connected to the attic. Jun 9, 2020 at 16:19
  • mines a heat pump. no gas furnace. Jun 10, 2020 at 2:13
  • 1
    Additionally, "leave it alone" can be a perfectly good and valid answer if there's nothing to worry about and no changes should be made to a professionally installed system that was installed according to the manufacturer's directions and all current conventional wisdom.
    – FreeMan
    Jun 10, 2020 at 17:16

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