IR Temperature Measurement

In the process of building my HI toolkit, it is apparent that I should have a decent IR hand-held temperature measuring device. After doing some research, it appears that there are many on the market with fairly widely varying specs. That said, I am interested in hearing recommdations from some of you experts on the subject. In other words, how did you decide on the unit you bought and use and would you make the same choice again and why? What specs do you consider important? How to get the most useful instrument for the price? TIA

I use the BCAM by FlIR., but you could save $5,500 and buy something else.
This allows me to measure and SEE temperatures.

I think you are referring to a handheld laser infrared thermometer…Not an infrared camera…right? If so, the distance-to-spot is an important feature for accurate reading from far away. Others might have other points of view.

That’s correct - the camera is a bit pricey for someone just starting out. As for the thermometers, I see some that are pretty cheap (under $100) and others that cost a lot more. For home inspection purposes how accurate does it really have to be? Can someone explain the ‘distance to spot ratio’?

Small so you can keep it with you all the time.

Laser so you can ID the spot you are looking at. A Laser that shoots from the lens is more accurate as you don’t have a parallax problem.

Common batteries for easy replacement.

The ability to change emissivity settings (may say "light-dark object on a switch).

And just check on the specs to see that it is the tool for your use. High end units can shoot more accurate at further distance (which you may not need).
Cheap units, you have to just about touch the object for accuracy.

If you do not understand the “spot” of view they are talking about, it is the size per distance that the unit sees. The unit averages everything inside this spot to give you a reading. If the object does not fill the spot, the measurement will not be the results you are looking for.

Whatever you buy, test its accuracy by point it to boiling water. You should get around 212 F. depending on how high above sea level you are. Some of the cheaper ones are way off.

They are handy, but should not be used to test the air differential. They are handy to test the register teperatures quickly though.

So what is your recommended test equipment for air temperature?

I see units specified as 5:1, 10:1 etc. but am not really sure how to use that ratio.

5:1 10:1 is the area it covers per foot away from the object 5 inches etc. 3 feet away = 15"s. to check the furnace or air conditioner use a small therometer, $3 or so. Insert in the duct work one foot from the main stack and the same for the air return. Digital ones change quicker and are only about $5. You can monitor the limit switch when the heat drops back off when the limit switch kicks out and the blower is still running. the furnace will cycle on and off. The difference in the air conditioning should be between 12 and 22 degrees with a clean filter and the unit has been running a while.

A thermistor type thermometer is the most accurate, responsive and can be calibrated with a glass of ice water (in many models).

If you are doing delta T’s for HVAC evaluation, get a hygrometer. It will tell you something you can actually use.

The IR thermometer is great for things you can’t reach, or touch (Like a 240 VAC electrical conductor with the power on). Still you are using this as a qualitative rather than a quantitative measurement. So accuracy is not so critical.

My infared thermometer is an 8:1 ratio, 8" away it reads a 1" circle 8’ away it reads a 1’ circle.

Accuracy of the exact reading is not important, accuracy of the delta is what you are looking for, that is why we look for a delta range. :smiley:

two pack gets the job done nicely

Excellent suggestion - I’ll look for that item the next time I am in Sam’s (nearest one is about 100 miles RT). Many Thanks.