Non-Contact Infrared Themometers

[Marcia Maynard]

I recently became aware of the benefits of owning and using a non-contact infrared thermometer. 

Here is a great link from the NDSU Extension office:
"A simple way homeowners can check their homes for heat loss is with an infrared thermometer. Infrared thermometers vary in cost, but generally are around $50. Depending on the season, a homeowner can find areas in a home where air and heat are leaking. The bigger the difference between the inside and outside temperature the easier it is to detect heat leaks. The North Dakota State University Extension service has developed a publication Determining Insulation and Air Infiltration Levels Using an Infrared Thermometer that describes the process of evaluating your home for heat leaks."

https://www.ag.ndsu.edu/pubs/ageng/structu/ae1373....

I'm shopping for a non-contact infrared thermometer that offers the best value and was surprised to find so many brands available, different features, range of quality, etc.  Anyone using these and have a favorite? Any tips about using them?

[Matt R.]

Originally posted by @Marcia Maynard:

Any tips about using them?

Keep in mind that the area that it "sees" the temperature of gets wider as you get further away from the surface.  The manual should tell you the width of the area it is measuring, at various distances.  Some of them have an integrated laser pointer, which shows you the center of the area it is measuring, but the total area will be a circle centered on that red dot.  Put an ice cube in the middle of a table and take readings at various distances... if you're next to the ice you'll get pretty close to 32 (or 0), but as you get further away, the temperature will go up.

Also, some materials are better at emitting infrared than others.  If you heated samples of two different materials to the same internal temperature, you would get different amounts of infrared radiation from them.  The measurement of this is called "emissivity" and runs from 0 to 1.  It works out that "most" things have an emissivity of 0.9 or more, so a lot of infrared thermometers used a fixed emissivity value of around 0.9 to 0.95.  Things that are shiny/reflective have lower emissivity, though... if you need to measure things like that, it can help to get a thermometer with adjustable emissivity.

Once you've done everything you can with an infrared thermometer, the next step up is an infrared camera.  These are made by FLIR, who is very, very proud of them.  Usually, somebody like a home inspector buys one for several thousand dollars, and then pays for it a little at a time by using it on many inspections.  You can "see" where the studs are in walls, if a ceiling has water behind it, and even overheated electrical connections.