DIY Thermal Imaging

Flir’s lowest-cost handheld thermal camera provides a resolution of 60 by 80 pixels.
This thermal image, taken during system troubleshooting and testing, reveals hot intercell connections inside a PV module.
The Flir One Pro (Gen 3) offers 1,440 by 1,080 pixels in a unit that attaches to an iPhone or Android.

There are many uses for thermal imaging, including finding air leaks, poorly installed or gaps in insulation, and thermal bridging. You can also use the cameras to find blockage in waste plumbing, underslab leaks in hydronic heating systems, leaks in flat roofs, and electrical faults. They can also be used to spot problems in PV arrays, such as poor intercell connections, underperforming modules, and defective bypass diodes.

This technology was previously the domain of professionals, mostly because the cameras were expensive. When I first heard of thermal imaging in the 1970s, the cameras cost up to $100,000. Today, you can purchase a basic thermal imager that attaches to a smartphone for $200 (or a pro version for $400). A good stand-alone imager is about $500; a cheap “brand X” imager sells for less than $100.

While you might be able to afford an imager, just how easy is it to use it and interpret the results? Well, that depends. The companies that manufacture the cameras often include online interpretation instructions, and there are multiple online videos that can help. Flir’s Thermal Imaging Guidebook explains imaging and how to use the cameras (

Some images may be very simple to interpret, but knowing how to fix a leak, for example, requires another level of know-how. Should a leak that is identified on an interior image be sealed from the inside, should foam insulation be added to the wall cavity, or is it a symptom of a greater problem with the building envelope? Having a camera does not fix the problem and the images it generates may not reveal underlying issues, but it can provide a helpful start.

Comments (1)

RMichael Curran's picture

There's now a cellphone available that has the flir thermal imaging device built-in, the Cat S-61. Not cheap but kinda neat.

Show or Hide All Comments