Curosity kills the cat

But satisfaction definitely brings it back.

When I see something with the IR Camera that makes no sense I will not leave the home until I have an answer. I had an interior wall between two bedrooms that had identical hot spots on both sides of the wall that basically traveled from the top plate to the floor as viewed from within both bedrooms.

This dividing wall naturally joined the exterior wall on the east side the time of day was roughly 2 PM no sunshine on the exterior wall, bedroom windows on the east The gas Pak A/C unit was located just on the opposite side of the exterior wall on the ground level and was operating at the time. This was a slab foundation with the A/C ducts embedded within the slab.

The hot spots on the interior wall had to do with the A/C unit what do you suppose I found when I went into the attic???

My guess is: poor framing in combination with no insulation, and attic heat was flowing down the wall?


We’ll take a couple of SWAGs given your description and the photos. At the top of the first wall section, closest to the outside wall, the temp is registering near 93+ Degrees (about the temp of a liquid line). Was the liquid line brought down into that cavity, routed near the top, before it exited the outside wall framing just below the top plate. From there it was run between the wall cladding and sheathing (if the wall cladding was brick). The heat all around it appears to be from conduction as the temperature gradient starts dropping the farther you get from that point. It is also a possibility that the wall studs were notched at the top and the liquid line was run in the notch, without benefit of any nail plate protection, before it emerged above the top plate of the wall and into the attic.

Another guess would be a lack of fireblocking in the attic at that point and the heat from the liquid line is being drawn in at that point.

Like I said a couple of SWAGs until we hear more detail.

He stated a gas pack A/C unit, no refrigerant lines exist except inside the one piece packaged unit outside.

I wonder where the return duct runs?
Must be sucking in hot air from the attic via the wall cavity somehow…

Hi Charlie,

were they using the cavity wall space as a supply plenum?



Hi Gerry if it was used as a supply plenum with the A/C in operation would not have been reading in the 90’s;-) Slab floor not a crawl

Here is a pic of the outside unit No refrigerant lines

Hi Bruce you got it right except for the sucking part. There was a chase with the metal return air duct within the chase but the chase was open at the top into the attic and no insulation on the bedroom interior walls the attic temp was just cooking these two walls.

Great post Charlie,
But I am confused as to why the chase was open to the attic? I would expect it to be closed off in some way.

This type of construction is not common here but have seen a few this way. They frame the chase in, install the plenum the rectangular plenum as in the pic just penetrates the brick veneer and then they install the round return duct vertical all of the way up to the attic level and 90 over to the ceiling plenum’s where the return air grills are located.

The area into the attic where the 90 was located was where the heat from the attic was effecting the walls this area should have been sealed at the attic level. It will be after my report gets submitted. Difficult to just state in the report need to seal this area to prevent temp intrusion and actually get someone to do it. If one can show a pic of the area in IR with the temp glaring at them I find better results

Thanks for the explanation Charley.