The Best Thermal Imaging Cameras For Finding Leaks And Cold Spots
Five thermal cameras for tracking down cold radiators and draughty windows.
Our quick verdict
Our pick of the best thermal imaging camera is the FLIR ONE EDGE PRO. It's small enough to keep in a pocket, works with iPhone as well as Android, and saves images straight to your phone, so you can send a cold radiator to a plumber in seconds. If you'd rather have a standalone camera that works out of the box, the TOPDON TC004 Thermal Imaging Camera is very easy to use.
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Our Picks At A Glance
- Check price of FLIR ONE EDGE PRO
Best Smartphone
FLIR ONE EDGE PROiPhone and Android users who want a pocketable wireless thermal camera
- Check price of TOPDON TC004 Thermal Imaging Camera
Best Value
TOPDON TC004 Thermal Imaging CameraHomeowners and landlords who want a standalone camera ready out of the box
- Check price of Bosch GTC 400 C Thermal Camera
Best Professional
Bosch GTC 400 C Thermal CameraPlumbers, electricians and surveyors who need reports for customers
- Check price of TOPDON Thermal Imaging Camera for Android
Best Smartphone Runner Up
TOPDON Thermal Imaging Camera for AndroidAndroid users who want sharp thermal images for the money
- Check price of PerfectPrime IR0280 Thermal Imager
Best Budget
PerfectPrime IR0280 Thermal ImagerOccasional checks for leaks and insulation gaps on a tight budget
Thermal resolution is the number to read in the listings, and it's easy to confuse with the visible camera resolution printed alongside it. A low-resolution sensor shows a cold radiator well enough, but tracing a pipe under the floor or the edge of missing insulation needs more pixels. Then decide between a phone add-on, which costs less for the image quality and puts pictures straight on your phone, and a standalone camera that's tougher and quicker to grab.
We've used both types on our own properties, and the five picks run from a trade Bosch to a budget imager.
Diagnosing Faults With These Thermal Cameras
We own a number of properties, including Airbnbs and rentals, and we're regularly asked to diagnose problems where a thermal camera is the quickest tool for the job. We've used them on everything from electrical faults to leaks.
The two photos below were taken while testing a handheld camera whose brand isn't readable on screen, so we don't tie them to a model in this list. The first shows a radiator that wasn't heating at the bottom, with the screen reading 54.7°C at the centre point, a maximum of 56.4°C and a minimum of 16.6°C. The second shows cold air getting in around a window frame.
Each reading shows the spot temperature along with the hottest and coldest points in view, and the colour scale makes the cold areas obvious even if you've never used one before. The emissivity on both screens is set to 0.95, which suits most painted and matt surfaces around the house.
We've also been using the FLIR ONE EDGE PRO, which connects wirelessly to a phone. The first photo below shows the camera itself, and the second is a screenshot straight from the phone, with a cold window and a hot appliance clearly marked.
The Short below shows us testing the TOPDON TC004 on a radiator that isn't heating fully, so you can see how the readings update live as you move the camera.
Watch Us Test This Thermal Imaging Camera - Easy Diagnosis of a Radiator Not Heating Fully #shorts
When a brand brings out a newer model, we try to get hold of it so this list stays current. Every camera was rated on the same points:
- Accuracy: how close the readings are and whether emissivity can be adjusted for different materials
- Image quality: thermal resolution and how clearly hot and cold spots show
- Ease of use: how quickly you can pick it up and get a useful reading
- Saving and sharing: storing images and video, and the apps or software for reviewing them
- Build: how well it copes with drops, dust and damp
- Extras and value: accessories in the box, warranty and price
Our Recommended Thermal Imaging Cameras
Two of these work through a phone and three are standalone cameras. Temperature ranges are the makers' figures.
Best Smartphone
FLIR ONE EDGE PRO
Best for: iPhone and Android users who want a pocketable wireless thermal camera
Check Price On AmazonThe FLIR ONE EDGE PRO is FLIR's newer phone-based thermal camera, and it now works with both iOS and Android phones and tablets. It connects wirelessly, so you download FLIR's app, follow the setup on screen and you're taking thermal images within minutes. Anyone comfortable with a smartphone will find it easy for home inspections.
One detail we liked in testing is the extendable USB connector, which meant we didn't have to take our phone out of its case to plug it in. Images and video save straight to your phone, so sharing a photo of a cold radiator with a plumber or a tenant takes seconds. FLIR quotes a range up to 400°C.
It costs more than other phone-based cameras, including the TOPDON TC001 further down.
What we like
- Works with iOS and Android phones and tablets
- Wireless connection to your phone
- Extendable USB connector meant we didn't need to remove our phone case
- Saves images and video straight to your phone
- Measures up to 400°C according to FLIR
- Simple setup through FLIR's app
What to know
- Costs more than the TOPDON TC001 phone camera
- Relies on your phone's battery and screen
Our verdict
Buy the FLIR if you want thermal images on the phone you already carry, whichever make it is, with sharing as simple as sending a photo. Android users can spend less on the TOPDON TC001, which TOPDON rates at a sharper 256 x 192 resolution.
Best Value
TOPDON TC004 Thermal Imaging Camera
Best for: Homeowners and landlords who want a standalone camera ready out of the box
Check Price On AmazonThe TC004 is a standalone handheld camera, so it doesn't need a phone and works straight out of the box. We found it very easy to use, and it's the camera in our YouTube Short. The display is clear, with centre, hot spot and cold spot readings, and you save an image by pressing the trigger.
The built-in torch proved useful when we were crawling through a roof space, and you can adjust the emissivity for different surfaces. TOPDON says it can survive a 2 metre drop. In the box you get an SD card, a carry case and a charger.
Viewing saved images means taking the SD card out and putting it in a computer with TOPDON's software, and its 350°C maximum is lower than the other cameras here.
What we like
- Very easy to use in our testing
- Built-in torch that helped us in the roof space
- Clear centre, hot spot and cold spot readings
- Adjustable emissivity for different surfaces
- Survives a 2 metre drop according to TOPDON
- SD card, carry case and charger included
What to know
- Saved images can only be viewed by moving the SD card to a computer
- Measures up to 350°C, lower than the other cameras here
Our verdict
Easy to pick up and use, with a torch that earned its keep in our roof space, the TC004 is the handheld we'd recommend for checking radiators, draughts and lofts. Getting images off it means a trip to the computer with the SD card, so anyone who wants instant sharing is better off with a phone camera like the FLIR ONE EDGE PRO.
Best Professional
Bosch GTC 400 C Thermal Camera
Best for: Plumbers, electricians and surveyors who need reports for customers
Check Price On AmazonThe GTC 400 C is Bosch's professional thermal camera and the dearest in this roundup. It's built for plumbers, electricians and other trades who'll use it every week and need to show customers what they've found.
It has a large colour display with a 160 x 120 pixel infrared sensor, and it links to Bosch's Measuring Master app. Photos are stored on the camera and can be sent to your phone, where the app turns them into reports you can pass on. Bosch rates the body at IP53, so it copes with drops and splashes on site.
Power comes from a Bosch lithium battery pack or AA batteries, which is handy if you forget to charge it. It comes with several accessories and measures up to 400°C according to Bosch.
What we like
- IP53 rated body for drops and splashes
- Runs on a Bosch battery pack or AA batteries
- Builds reports through the Measuring Master app
- 160 x 120 pixel infrared sensor
- Transfers photos to your phone
- Measures up to 400°C according to Bosch
What to know
- The most expensive camera in our roundup
- More than most homeowners need for occasional checks
Our verdict
The GTC 400 C is built for trades who need to hand customers a proper report, with the IP53 body taking site knocks and Bosch's app doing the heavy lifting. It's the most expensive camera here, and homeowners checking their own radiators and windows will be better served by the TOPDON TC004.
Best Smartphone Runner Up
TOPDON Thermal Imaging Camera for Android
Best for: Android users who want sharp thermal images for the money
Check Price On AmazonThis is TOPDON's TC001, a plug-and-play thermal camera for Android phones and tablets that also works with Windows computers. Unlike the TC004 above, it uses your phone's screen rather than its own.
The specs are strong for the price. TOPDON quotes a 256 x 192 pixel resolution and 40mK thermal sensitivity, which means sharper, more detailed images than the PerfectPrime and a higher resolution than the Bosch. It reads from minus 20 to 550°C, giving it the widest range of the phone cameras here, and you can pick from 9 colour palettes to suit what you're looking at.
TOPDON also says it uses less power than its earlier models, which helps when it's drawing from your phone. The big limitation is that it doesn't work with iPhones or iPads.
What we like
- 256 x 192 pixel resolution according to TOPDON
- 40mK thermal sensitivity
- Reads from minus 20 to 550°C
- Choice of 9 colour palettes
- Plug-and-play on Android and Windows
What to know
- Doesn't work with iOS devices
Our verdict
Android users get the sharpest quoted resolution here for the money, plus a wide temperature range and nine colour palettes. It simply won't work with an iPhone or iPad. Anyone who prefers a camera that doesn't depend on a phone should look at the standalone TOPDON TC004.
Best Budget
PerfectPrime IR0280 Thermal Imager
Best for: Occasional checks for leaks and insulation gaps on a tight budget
Check Price On AmazonThe PerfectPrime IR0280 costs a fraction of the other cameras here, and it'll still find hot and cold water leaks, gaps in insulation and radiators that aren't heating properly. It's easy to use out of the box, runs on a rechargeable lithium-ion battery and records video when you pull the trigger.
The feature that impressed us in testing was the ability to live stream data to a computer, which is handy if you want to watch a reading change over time on a bigger screen. PerfectPrime quotes a temperature range up to 1,000°C.
The compromises show in the build and the image. In our testing it didn't feel as well made as the others, and the 32 x 32 pixel thermal resolution gives a grainy picture, so small details are harder to pick out.
What we like
- Live streams data to a computer, which impressed us in testing
- Easy to use out of the box
- Records video with a pull of the trigger
- Rechargeable lithium-ion battery
- Temperature range up to 1,000°C according to PerfectPrime
What to know
- Didn't feel as well built as the others in our testing
- Grainy image from the 32 x 32 pixel thermal resolution
Our verdict
For the odd job on a tight budget, the PerfectPrime still finds leaks and cold spots, and live streaming to a computer impressed us. The grainy 32 x 32 image and a build that didn't feel as solid as the others in our testing are the trade-offs. If you'll use it regularly, the TOPDON TC004 is worth the extra.
What Matters When Buying A Thermal Camera
Thermal cameras range from cheap imagers to trade tools costing several times as much. For home use, the right one depends on how you want to view the images and how much detail you need to see.
Standalone Or Phone Camera
A standalone camera like the TOPDON TC004 or Bosch GTC 400 C has its own screen, battery and buttons. It's tougher, quicker to grab and doesn't drain your phone. Phone cameras like the FLIR ONE EDGE PRO and TOPDON TC001 are smaller and cheaper for the image quality, and saving and sharing is easier because the pictures land straight on your phone. Check compatibility before buying, as some only work with Android.
Thermal Resolution
Thermal resolution is the number of heat-sensing pixels, and it's the spec that makes the biggest difference to what you can see. A 32 x 32 sensor will show a cold radiator but blurs smaller details, while 160 x 120 or 256 x 192 lets you see individual pipes under a floor or the edge of missing insulation. Ignore the visible camera resolution in listings, as that's a separate sensor.
Accuracy And Emissivity
Different surfaces give off heat differently, which is what emissivity measures. Shiny metal, glass and chrome can fool a thermal camera into reading too cold. A camera with adjustable emissivity lets you correct for that, and our own readings were taken at 0.95, which suits most painted surfaces. For shiny pipes, a strip of matt tape gives a truer reading.
What You'll Use It For
Around the home, the most common jobs are finding cold patches on radiators, tracing leaks, spotting draughts and checking for missing insulation. A radiator that's cold at the bottom points to sludge, and our guide on draining a central heating system explains how to flush it out. If the whole system keeps dropping pressure, see why your boiler keeps losing pressure, as a hidden leak is one cause a thermal camera can help find.
Cold spots on walls and ceilings can also show where damp and mould are likely to form. If you're checking under floors, our guide to floor insulation covers how to fix any gaps you find.
Saving And Reporting
Think about what happens after you take the picture. If you'll send images to a tenant, a plumber or an insurer, a phone camera or one with an app like the Bosch makes that simple. Cameras that store images on an SD card work fine but mean an extra step at the computer.
Thermal Imaging Questions Homeowners Ask Us
Can a thermal camera find a water leak?
Yes, a thermal camera can find a water leak by showing the temperature difference the water causes. A leak from a hot pipe shows up as a warm patch spreading across a floor or wall, while a cold water leak shows as a cooler area. It works best with the heating or hot water running, and it can't see through thick walls, only the surface temperature.
Can a thermal imaging camera see through walls?
No, a thermal imaging camera can't see through walls. It reads the surface temperature, so it shows heat that has travelled through to the surface from pipes, cables or gaps in insulation behind it. That's why hot water pipes under a floor or a cold bridge in a wall show up, but you won't see objects inside a cavity.
Why is my radiator cold at the bottom?
A radiator that's cold at the bottom but hot at the top has sludge settling inside it, which blocks the water from flowing through the lower part. A thermal camera shows this clearly as a hot band along the top fading to cold underneath. Flushing the radiator or the whole system clears it, and a magnetic filter helps stop it coming back.
Is a phone thermal camera as good as a handheld one?
A phone thermal camera gives good image quality for the money, as it uses your phone's screen rather than its own. A handheld camera is tougher, quicker to use and won't drain your phone, which matters for regular use or in dusty places. For occasional home checks, a phone camera is the better value.
Do I need to change the emissivity setting on a thermal camera?
Set emissivity to 0.95 for most painted and matt surfaces around the house, which is what our radiator and window readings used. Shiny metal, glass and chrome can fool a thermal camera into reading too cold. A camera with adjustable emissivity, such as the TOPDON TC004, lets you correct for that, and a strip of matt tape on shiny pipes gives a truer reading.
Should I buy the TOPDON TC004 or the FLIR ONE EDGE PRO?
Buy the TOPDON TC004 if you want a standalone camera that works straight out of the box, with a torch that helped us in a roof space. Choose the FLIR ONE EDGE PRO if you want to share images instantly, as it works wirelessly with iPhone and Android and saves straight to your phone. The TC004 needs its SD card moved to a computer.
Is the PerfectPrime IR0280 good enough for finding leaks?
Yes, the PerfectPrime IR0280 still finds hot and cold water leaks, insulation gaps and radiators that aren't heating properly. The compromise is a grainy picture from its 32 x 32 pixel thermal resolution, so small details are harder to pick out. It didn't feel as well made as the others in our testing, but live streaming to a computer impressed us.
Does a homeowner need the Bosch GTC 400 C?
No, most homeowners don't need the Bosch GTC 400 C. It's the most expensive camera in the roundup and is built for plumbers, electricians and surveyors who need reports for customers, with an IP53 body and the Measuring Master app. For checking your own radiators and windows, the TOPDON TC004 does the job.
Our Choice Of Thermal Imaging Camera
The FLIR ONE EDGE PRO is our top thermal imaging camera, a pocketable camera that works wirelessly with iPhone and Android and puts every image straight on your phone. If you'd rather have a standalone camera, the TOPDON TC004 is the one we found easiest to use, and its torch helped us in a dark roof space.
Trades who need reports should look at the Bosch GTC 400 C, and Android users on a budget get sharp images from the TOPDON TC001.
Richard has spent years renovating properties and turning them into rentals and Airbnbs. Like a lot of people he started out as a beginner, and these days there isn't much DIY he won't take on.