Charley, I’m talking in the heating mode also. My questioning as to whether this is a significant deficiency is more about are we going to be able to prove our claims to the HVAC industry when we start calling out this stuff.
It’s an interesting topic. One of which I have not personally analyzed. But the hypothesis that 3 feet of buried uninsulated refrigerant line is an energy loss (for such a short distance) just doesn’t seem much of a significance to me.
A lot of home inspectors callout uninsulated refrigerant lines from the house to the condensing unit, and I feel the same way about that.
Just as with geothermal equipment, the amount of heat transfer is based upon the length of the pipe buried in the ground or water.
Do we really have enough length to even measure a significant difference? I can do the math and prove that you are correct that there is a loss, but just how much is going to be too much?
Heat transfer in fluids (moving air and water) is much greater than the heat transfer through conduction in the ground. So an uninsulated line above ground
is probably going to be worse than below ground.
We are pulling high velocity turbulent air that is 30° hotter/colder than the outside air across a significant amount of piping located inside the condensing unit that is not insulated by the manufacturer. They don’t bother to insulate those lines?!
Good conversation
Just don’t want newbie home inspectors to start trying to call this stuff out and get into a head-to-head conflict with the HVAC industry and the real estate agents.
I would be very interested to know exactly what the MFG had to say about burying a uninsulated hot gas line from a heat pump. I am of a different opinion than you on this. I did a IR job for the service sup for the Trane campany recently and I have his E-mail address so I will shoot this discussion to him and see how he responds Have a happy thanks giving My Tennessee Buddy
One of the requirements is that you properly tune the scan.
As Mr. Moore pointed out your level and span our way out of whack for whatever your target was supposed to be.
Your temperature reflect target should be set on “average” and not “minimum/maximum”.
It should also be at the same angle as your target.
What is the spot measurement tool on the house for?
If it was for determining outdoor air temperature, I recommend you make an ambient air target from your temperature reflect target as well.
What was your point in taking the scan?
It appears you are trying to show a temperature differential between the deflector and the siding of the house.
You cannot adjust emissivity in one thermal scan when you have two dissimilar targets you are measuring. You must take two separate scans.
I see no attempts to adjust emissivity at your spot measurement locations (but they are out of range so I can’t see).
The shape of the deflector is conical. Is the location of your spot temperature tool in the right location, taking into account emissivity changes due to angle of view?
In the digital photograph you can see reflective changes. There’s a high probability that you also have infrared reflection issues involved.
If you’re trying to measure the temperature of the air coming out of the condensing unit, you should be utilizing a known target placed in the air stream to take your measurements from (just as trying to determine the outside air temperature).
Interesting thread. I am thinking like Charley on this one as well. I would think there would be an efficiency concern.
Also, what about the potential that the lines could be damaged by objects or rocks buried against it in the soil as well? Vibration as we all know is a significant concern. Leak detection underground would be interesting as well.
Sorry Charlie for butting in, I should have posted this on a new thread.
Jeffrey and David, thanks for your constructive criticism.
Yes I pass but the field assignment was only part of it, lucky me…;-)
What I was trying to show is warm air from the heat pump in cooling mode being deflected on the house which it is trying to cool (and vice versa if in heating mode).
This may sound insignificant to some much like a buried suction line, but to me it is worth noting and heat pump manufacturers should have snow covers designed to deflect air away from house and not directly on it.
I am presently toying with the camera and any advice/comments are welcome.
Bill, can you expound on why you think this would be an energy efficiency concern? Interested in your perspective.
As for the lines being damaged, refrigeration copper piping is the heaviest piping they make. Not much chance of damage.
Vibration: the pipe won’t vibrate when they’re buried in the ground!
Leak detection: is difficult to do inside of a wall and ceiling as well.
Somebody needs to take a thermal scan of pipe buried in the ground and see just how much heat transfer is occurring.
In my opinion the pipes should be insulated or sleeved if they are buried under the ground (just like anything else). But we are discussing energy loss.
What is the specific heat of “dirt”?
Clay is; 0.22 Btu/lb m°F
Air is: 0.2375 Btu/lb m°F
Not much difference!
The big difference lies between solids and fluids. Fluid movement (convection) can extract a significant amount of heat versus a solid they rely solely on conduction without convection.
You know, windchill factor!?
Would you lose more heat driving your motorcycle down the road in the wintertime or buried below a sand castle at the beach at the same outdoor air temperature?
Great points Mike. I was thinking along the lines that the temperature of the soil was considerably higher than what we nomally see in this area. I think he mentioned around 100 degrees F surface. But, alas they would be subject to the same radiant heat if they was not buried. They probably are better off in the ground in that case.
Also, I just wonder about the transitional stress imparted on the lines as they run from the unit to the ground. However, after considering your response, it would be no different than passing through a wall without adequate isolation.
I think a better test would be to strap a temp sensor to the line and cover it in the manner of a TXV expansion bulb just as it leaves the unit and again just before it enters the indooor coil and measure the temp loss
