Avoid These Hot Mistakes
Thermal imagers are relatively simple devices, but like any diagnostic tool, it’s possible to make mistakes with time. Novice users may forget to set up the ranges on the camera or overlook whether the measurement is in Celsius or Fahrenheit.
The first rule of thermal imaging is to remember that unlike Superman, thermal images don’t see through objects – they can’t look behind walls, doors, or covers. “They only see the first 1/10,000 of an inch of the energy radiating off of a surface,” explains Lux.
This is most commonly forgotten when searching for moisture problems.
“It’s a myth that you can detect a water leak behind a wall,” notes Jeff Abramson, director of thermography development with tool developer Fluke. “You can only spot moisture intrusion if the wall material easily conducts heat or the water changes the surface temperature of the wall. Drywall is a good example – I can stand behind a panel, spray water on it, and a thermal camera will read it on the other side. But if a water leak is running down a pipe and pools below your floor surface without affecting the wall, you probably won’t see it.”
Users often overlook the concept of emissivity. "Emissivity is the property of a surface to emit energy via radiation. Getting an accurate temperature of a bright metal surface is extremely difficult," Abramson adds. "A thermal imager will often provide a table of common materials and their emissivity values. However, just setting your thermal imager to that emissivity may not give you an accurate reading."
Emissivity also applies to glass – it will reflect back your own heat signature if you’re standing at the right angle. “Sometimes the angle can be difficult if a reflection is amplifying the thermal read,” explains Woodroof. “Just like the glare from the sun while driving, the glare from a window can create a false impression of the heat signature. You may need to adjust the angle that you take the reading from to get a proper measurement.”
Measuring objects outside can also be tricky because you need to pay attention to wind speeds, Abramson stresses. Even a 10 mph breeze will give you a much lower temperature reading than what the object really is. This can also be a problem inside if you have fans running or are scanning something under a hot air return.
It’s important to read equipment during normal operating loads.
“If you’re looking at a target in an electrical distribution system, you can’t expect to find a problem if it’s not under load,” cautions Scanlon. “Some people make the mistake of taking measurements on their switchgear under irregular building conditions, such as when a production line is offline or operating at a reduced load.”
Thermal imagers are often confused with handheld spot temperature guns. Both use infrared, but thermometers measure only one point, as opposed to the thousands of points a thermal camera uses, says Mavrides.
Use an IR thermometer only if you know the location of a problem (e.g. the sealant on the second window from the left) and leave the infrared camera for when you’re not sure if a problem exists in the first place.
Justify the Cost of a Camera
There’s no doubt about it – thermal cameras are a pricy addition to a facility manager’s tool belt.
“A good quality camera will cost between $3,500 and $9,000,” Lux observes. “But the price of handheld cameras has really dropped – 10 years ago, the same model could have been around $40,000.”
When selecting a camera, carefully look at the warranty, recommends Lux. Depending on the application, some thermal images need to be recalibrated annually – at $700-1,500 per adjustment, this represents an ongoing investment. Some companies may include recalibration in the warranty.
Others might offer a one-time replacement if the camera is accidentally broken. The tools are typically built to withstand modest drops, such as from a ladder, but a trip from the roof to the pavement below will cause irreparable damage.
Large facilities or those that are mission critical are most likely to own thermal imagers and use them extensively, says Woodroof. Smaller properties are apt to have them for troubleshooting specific equipment but will still hire an outside electrical firm for yearly inspections.
“A building can have a particular system that benefits from regular thermal imaging,” notes Abramson, “but the person specializing in that component may not consider pointing the camera at the roof to look for moisture. A contractor will look at the whole building.”
It’s important to keep track of savings opportunities you uncover with your thermal imager to help quantify payback.
“For $2,000, you can buy a tool that produces high resolution thermal images with over 19,000 pixel elements,” says Scanlon. “If in the first week of using a thermal camera you haven’t found at least the price of the tool in savings opportunities, you’re not using it right.”
Not only will it catch problems that you literally can’t see, but a thermal camera can decrease labor costs, keep workers safe, qualify you for insurance breaks, and increase the frequency of inspections you can perform.
Thermal imagers can also provide leverage when you need approval for upgrades. Instead of taking an incomprehensible spreadsheet of data to company leadership, you can show them a visual that instantly makes the problem clear.
“I once found about a mile of uninsulated pipe in the steam trap tunnels at a facility,” says Woodroof. “It’s really helpful to have a picture of a deficiency like that and take it to a CFO to request funding.”
If the cost still seems steep or you want to test the tool before purchasing one, some utilities, cities, or large companies have a tool library where you can rent or check out a thermal imager, notes Woodroof.
“The bottom line is that any time you find that your building is compromised, you are losing money – dollars are going right out your roof, windows, and doors,” argues Scanlon. “There’s so much about your building that you can understand with a thermal camera that you wouldn’t see otherwise. There will be a time when every facility manager uses an IR camera and wonders, ‘How did I ever do my job without one of these?’”
Jennie Morton email@example.com is
associate editor of BUILDINGS.