The colorful world of thermal imaging — Part 2

At the end of last month’s article, we were discussing the potential application of this technology for locating leaks below grade. That is but one of the possible applications in the HVAC field. The most obvious application is looking for energy leaks (heating or cooling) in the buildings shell and core. Again, differential in temperature is critical before attempting to look for energy leaks.

At the end of last month's article, we were discussing the potential application of this technology for locating leaks below grade. That is but one of the possible applications in the HVAC field. The most obvious application is looking for energy leaks (heating or cooling) in the buildings shell and core. Again, differential in temperature is critical before attempting to look for energy leaks.

For example, if you were trying to determine why a given dwelling was experiencing cool conditions inside when it is cold outside, you wouldn’t want to show up when the outside air temperature is hovering around 65ºF to 70ºF. There would not be enough differential to give good color difference to show where the weak links are occurring in the envelope. Conversely, you would not want to show up for an air conditioning audit when the outside air is hovering around 40ºF for the same reason. Wrong differential at the wrong time. It requires planning on the thermographers part to insure ideal conditions prevail for capturing an image of the potential problems. I have been known to show up on a jobsite at 4:30 a.m. in an attempt to locate a leak in a snowmelt slab prior to the sun coming up and causing a total wash out of the slab. You have to think ahead and plan accordingly.

Certain situations are not time sensitive, but still require some planning ahead to insure optimal observation conditions. For example, utilization of this technology to locate defective steam traps in a two-pipe, closed-loop steam process heating system requires that the system be up and operating completely before an assessment can be made. I once showed up at a microbrewery to perform an audit of their steam production/utilization facilities only to find out that they weren’t running any batches that day, so the steam system was shut down. Plan ahead.

Likewise, if you wanted to observe a water heating system in operation, don’t show up on a marginal heat call day and expect to see conditions anywhere near what they should be for ideal observations. While on the topic of observing a hot water heating system in operation, I will give newbies another hint to keep them out of trouble. Infrared cameras are looking at the energy emissions coming off of a given body. Certain materials can significantly affect the emissions of energy.

For example, copper and certain grades of steel can appear to be exceptionally cool, even though in reality, they may be hotter than blazes. When I find myself in a mechanical room, looking at a large amount of copper tubing, I will place a small piece of blue painters’ masking tape on the critical parts of the system that I am attempting to monitor to dull the emissivity of the pipes to show true surface temperatures. Then, when I am doing a statistical analysis, using the software that came with the camera, I can pinpoint those small targets to get an idea of the differentials I am seeing between pipes.

Another item to be aware of is thermal reflections. In my research and development of the radiant windows, I use the IR camera quite extensively, and have inadvertently discovered, that you can see reflections in the window that show "color," but when you get down to using the pixel analysis software, the surface temperatures are inline. In other words, don’t believe everything you "see." Colorization is important in reviewing, but comes with many caveats as I have explained here. Don't just depend upon color alone in your assessment and diagnosis. Get familiar with your equipment and specific applications so that you don’t get wrapped up in false positives.

At one point in time, there was only one source of supply for this type of product, and that company was known as FLIR, which is an acronym for Forward Looking Infra Red. They got their start in the defense business, but quickly realized their potentials in non-military applications. When I first got involved with IR, a basic camera cost $30,000. It also had a battery pack that came on a belt, and required a stout person to carry it around. It also had a small refrigeration system that had to cool down a reference cell and it required about 10 minutes of operation to get it to the point that it was ready to roll.

Tune in next month as we continue to discover this fantastic resource in controlling energy waste and managing energy use. Until then, don’t forget to check the batteries in your and your customers smoke and carbon monoxide detection alarms, and happy spring hydroncing.

Mark Eatherton is a Denver-based hydronics contractor. He can be reached via e-mail at [email protected] or by phone at 303-936-7606.

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