I Thought I Knew Thermal Imaging. I Was Wrong.
Most thermal camera buyers obsess over resolution and completely ignore real-world physics. Here's the thing: I was one of them. In 2019, I spent $3,800 on my first FLIR E8 Pro. Six weeks later, I had a $400 repair bill and zero usable data from my first three inspections.
That's when I stopped being a gadget guy and started being a tool operator. Two FLIR cameras, one pretty expensive multimeter mistake, and a load cell disaster later, I've documented enough errors to fill a small book. This is the condensed version.
Let's start with the question that brought you here: can thermal cameras see through glass?
The FLIR E8 Pro, Glass, and the $380 Lesson
No. They cannot. And I learned this the expensive way.
I was inspecting a building in November 2020. From outside, the windows looked warm – thought I'd found a massive heat leak. Took 47 images with my FLIR E8 Pro. Returned to site. Confirmed the leak. Paid for remediation. Re-inspected. Still showed hot.
Turned out I was reading the reflection of the sky and the warm interior objects behind me, not the glass itself. Glass is highly reflective and mostly transparent to long-wave infrared (the band FLIR sensors use). You're seeing a mirror, not a window.
Here's what the FLIR E8 Pro (and any thermal camera) actually sees:
Regular glass reflects 85-95% of thermal radiation. The remaining 5-15% comes from the glass itself. You can't see through it. Period. If you need to check a window's thermal performance, you inspect the frame and the seal – not the glass pane.
That mistake cost me $380 in wasted remediation and a damaged reputation with that client.
Three More FLIR Mistakes I'd Rather You Not Make
1. The FLIR K55 – Not a Toy, Not a Diagnostic Tool
Look, I get it. The FLIR K55 looks amazing. It's for firefighters. It sees through smoke. People ask me if they can use it for electrical inspections. The answer is kind of, but don't.
The K55 is built for high-temperature, smoke-filled environments. Its dynamic range is optimized for fires – 500°C to 1,000°C targets. An electrical panel running at 60°C? That's background noise to a K55. The camera might not even register it properly.
I saw a guy on a forum try to use his K55 to find a hot breaker. He spent an hour, got confusing readings, and almost called an electrician. Turns out the camera was fine – it just wasn't the right tool.
The right tool for electrical: FLIR E8 Pro or the EX-series. The K55 is for surviving fires, not diagnosing panels.
2. Load Cells and Thermal Cameras – A Weird Pairing I Got Wrong
This one's niche, but it cost me a $2,100 order. I work with load cells (force sensors) for industrial weighing. A client asked why their load cells were drifting. I used my FLIR to check for heat sources near the cells. Found nothing. Spent a week chasing ghosts.
The problem wasn't thermal. The problem was moisture ingress in the load cell cable. The thermal camera can't see moisture inside a sealed cable.
My mistake: I assumed thermal imaging would reveal any abnormality. It revealed the surface. The real issue was deeper. Now I have a rule: thermal first, but confirm with a multimeter or physical inspection.
3. The 110 Plus Essential Multimeter – I Skipped the Manual. Bad Idea.
I bought the FLIR 110 Plus Essential multimeter because I wanted a single-brand kit. Look, it's a solid meter. But I made the classic rookie error: I assumed it works exactly like my old clamp meter.
It didn't. The 110 Plus has a true-RMS function that needs to be engaged for non-sinusoidal waveforms. I was measuring a VFD-driven motor's output. The reading was wrong. I blamed the motor. Replaced a $2,200 drive. The original drive was fine.
The lesson: Read the damn manual. The 110 Plus is a great meter – once you understand its modes. And use it with your thermal camera, not as a standalone replacement. The combo is deadly: thermal finds the hot spot, multimeter confirms if it's electrical or friction.
Why Buyers Keep Making These Mistakes
Most people buy the FLIR first and learn the physics second.
Here's what I'd do differently:
Before you buy any FLIR camera, ask yourself:
- What am I actually looking at? Glass? Metal? Plastic? Each reflects/emits differently.
- Do I understand emissivity? If not, you'll miss half your targets.
- Will I need to measure through something? If yes, you probably need contact tools too.
The question everyone asks: 'What's the best FLIR camera?'
The question they should ask: 'What exactly do I need to measure, and will thermal be enough?'
That second question would have saved me thousands.
The $4,200 Truth
Between the window mistake ($380), the load cell misdiagnosis ($2,100), the VFD replacement ($2,200 plus labor), and the K55 misuse (no direct cost, but lost hours), I've personally racked up over $4,200 in thermal-camera-related errors.
I've documented every one. Now I maintain a pre-inspection checklist for my team. It takes 10 minutes to go through. It's prevented at least 7 repeat mistakes in the last 18 months. That's about $800 saved, conservatively.
So here's my final opinion: thermal cameras – FLIR or otherwise – are phenomenal tools. But only when you understand their limits.
Can they see through glass? No. Is a K55 for electrical work? No. Can a load cell problem always be thermal? No. Is a multimeter a substitute for a thermal camera? No. The combination is what makes it work.
The FLIR E8 Pro is an amazing camera. The FLIR K55 is incredible for its intended use. The 110 Plus multimeter is solid. But none of them is magic. They're tools.
And tools need operators who've learned from their mistakes.
I learned mine so you don't have to. Now go – but check the glass first.
