Analyize these

Dave A here is some info for you this would have had me scratching my head if the owner had not been present and answered some quetions for me

These images were from the interior looking at the exterior walls A/C
operating Delta T was 14 degrees the wall studs were metal with dry wall that one could see.

Question why can you not see the wall studs with that much delta T???

Thermal break, no studs touch both inner and outer wall?

They have to touch the inner wall

Staggered wall studs install.

Nope they were a standard wall install nothing special about them

Without talking to the owner my clue would have been the size of the A/C units there were 2 on this 5K+ home a 4 ton and a 2-1/2 ton

How long has the AC been running and Delta T reached?

How old is the home?

Length of time the ac had been running. not long enough for entire wall to change temp.

Does it have something to do with where the Delta T was measured or was it 14 in the room you took the photos?


Though we think of metal suds as highly conductive, there is little mass to conduct heat across the wall cavity.

Metal studs are more energy efficient than wood…

BTW: this is in direct conflict with all the miss-information posted on the internet that says otherwise…

So don’t start posting all that miss-information here. Thanks.

Do the math. How many BTU’s can pass through 16ga metal 3.5" long? (actually longer if you flatten it out).
This is about “volume” of heat energy, not the “rate” of heat energy transfer.

Metal also has a lesser ability to absorb heat energy than wood.

The amount of heat that passes through a length of thin metal is also widely displaced across a wide area where it contacts the sheetrock. Harder to measure because the BTU/mass is not sufficient to increase the temp of the sheetrock.

All the math in the world woud not have helped in this situation because behind the drywall all exterior walls and the ceiling had plywood installed to the interior with drywall attached to the plywood as the owner stated one can hang pictures on the wall anywhere.

As I stated above this would have had my thinking cap on had not the owner informing me before hand. I have never had a wall covered with both drywall and plywood on the interior side

Not many homes the size of this one in OKla with 110 degree summers with some humidity that can be cooled with the size of the units that were in use

built houses and remodeled kitchens for many years and all kits had plywood behind sheetrock. Hang boxes any where you want to.

I hear they do things like that east of the mississippi just not out here:mrgreen:

Hey Charley,

Is that little yellow square in photo four a switch?

The high thermal capacity of wood studs would allow you to see them in spite of an additional layer of plywood added. You can see the studs in a wood lathed plaster wall (even through the pictures on the wall of a closet).

Fourier’s Law:

Btu/hr = (thermal conductivity (55k) x thickness of material (.025) x the Delta T (14F in this case)) / length (width in this case) of the stud (A metal stud is about 7" wide).

…is the reason you can’t see the studs.

Not saying the added R-Value of plywood did not increase insulation of the wall.

It’s about the Mass.

Probably a dimmer, they give off a little heat due to internal circuitry.

Yes it was a switch but unlike any I have seen it was almost like a control panel had as many as 6 button for different lights.

This home had more extras than the law allows for common people

had a big closet for all the controls and alarms, moisture alarms by all 3 water heaters

Had two A/C stats on two zone systems the stat pads can control either unit or any zone. One pad on one side of the home and one on the other

good question.