Advice on reading thermal images
We have borrowed a thermal imaging camera (FLIR One) for a few days to identify heat leaks from house. Working from inside the house was relatively easy. Rooms were warm, with some cool spots in the corners of windows – nothing major. Easy to spot and fix.
We then took some thermal images from outside – the ambient temperature was 9-10C. The house was heated to 21-22C. Am I reading the thermal imaging correctly and that we're not really leaking signifiant heat?
Buy Bodge Buster – Homeowner Air Source Heat Pump Installation Guide: https://amzn.to/3NVndlU
From Zero to Heat Pump Hero: https://amzn.to/4bWkPFb
Subscribe and follow our Homeowners’ Q&A heat pump podcast
I think its better to get closer and do the exterior in much smaller sections to try to find cold spots or leaky areas.
Mitsubishi Ecodan 14kw ASHP + 500l Cylinder
Posted by: @editorWe have borrowed a thermal imaging camera (FLIR One) for a few days to identify heat leaks from house. Working from inside the house was relatively easy. Rooms were warm, with some cool spots in the corners of windows – nothing major. Easy to spot and fix.
We then took some thermal images from outside – the ambient temperature was 9-10C. The house was heated to 21-22C. Am I reading the thermal imaging correctly and that we're not really leaking signifiant heat?
Hi Mars,
The brighter the area the higher the temperature, so for images taken from outside, bright is bad, dark is good. Obviously the reverse applies when the images are taken indoors.
To ensure that it is not solar gain that you are measuring rather than heat loss due to poor insulation, I would suggest that you take the same images again as late as possible after the Sun has gone down.
Numerous test that I have performed would indicate that the fabric of a building can absorb quite a high degree of solar energy, even at this time of year. The energy from direct sunlight can be as high as 700W/m2.
@George, that's what we did inside. We did a lot of close ups. We'll do the same from outside.
Buy Bodge Buster – Homeowner Air Source Heat Pump Installation Guide: https://amzn.to/3NVndlU
From Zero to Heat Pump Hero: https://amzn.to/4bWkPFb
Subscribe and follow our Homeowners’ Q&A heat pump podcast
@derek-m, I had that same thought process. I did the exercise in the late afternoon which probably wasn't sensible. I think I'll do it again in the evening when the ambient temperature has dropped to 2-3C.
Buy Bodge Buster – Homeowner Air Source Heat Pump Installation Guide: https://amzn.to/3NVndlU
From Zero to Heat Pump Hero: https://amzn.to/4bWkPFb
Subscribe and follow our Homeowners’ Q&A heat pump podcast
Posted by: @editor@derek-m, I had that same thought process. I did the exercise in the late afternoon which probably wasn't sensible. I think I'll do it again in the evening when the ambient temperature has dropped to 2-3C.
I would suggest leaving the task as late as possible, since the fabric of the building can retain the heat energy for hours. An alternative would be early in the morning, just before or just after sunrise.
@derek-m, before sunrise is not going to happen 🤣
I'll go out tonight at around 23:00 and see what we can capture.
Buy Bodge Buster – Homeowner Air Source Heat Pump Installation Guide: https://amzn.to/3NVndlU
From Zero to Heat Pump Hero: https://amzn.to/4bWkPFb
Subscribe and follow our Homeowners’ Q&A heat pump podcast
I found that when taking images outside it was better to go closer so that there was no sky in the frame. The sky shows as a lot colder than the house, so the camera is having to colour a wide temperature difference. If you can exclude the sky the range to be coloured is a lot smaller so any leaky hot spots should be easier to spot.
@peterr, that's a very good tip. I think I need to get closer and cut out the sky because it's definitely "tainting" the colour spectrum.
@derek-m, I got up at 5 and took some shots – the house temperature was around 3C-4C, so 'better' than the 10C. Inside temperature at 21C.
In the two images I've posted, it speaks to your point @Peterr.
From a distance, I get "yellows" around the windows when the sky is captured – when close up, it's purples and blues. If you ignore the colours, and just read the C figures, you can still see leaks, but to be honest, I think the house is a lot better than I thought it was from an insulation perspective.
Buy Bodge Buster – Homeowner Air Source Heat Pump Installation Guide: https://amzn.to/3NVndlU
From Zero to Heat Pump Hero: https://amzn.to/4bWkPFb
Subscribe and follow our Homeowners’ Q&A heat pump podcast
@editor, when you took these images, did you also take one or two baseline shots? I've generally found it useful to have an idea of the temperature of something like a tree trunk at the same time so your 3-4degC reading can be seen in context of how much warmer the house is than its surroundings.
Certainly when I measured my house, I wasn't much interested in actual temperatures as much as temperature differences. My walls were getting to within 1-2 degrees of outside temperature and my double glazing was perhaps only a degree above wall temperature. The front door, however, was consistently about 5-6 degrees above outside temperature, so was an obvious candidate for replacement.
105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and SPH5000 inverter
1 x Myenergi Zappi
1 x VW ID3
Raised beds for home-grown veg and chickens for eggs
"Semper in excretia; sumus solum profundum variat"
@majordennisbloodnok, good points. To my mind, after the first couple of goes, I realised that while the colours are helpful they are not necessarily indicative of "heat losses" – what I did as part of my last session was to walk the length of the house and I took a reading of the brick work temperatures – they were typically in the range of 3-3.5C.
I then worked my way back the other way looking at windows and doors. The windows were all at 4.2-4.7C which to my mind isn't a massive differential.
This, to me, would indicate that we're not losing too much heat via the windows.
When inside the house, the colours were far more indicative of the temperature variations, and the corners of windows where you can sometimes feel air "movement" the temperatures were 1-2.5C lower than the room temperature. These gaps will all be sealed in the next few days. We have also received a groovy insulation cream that we will apply to the brickwork outside under the windows where we get some leaks.
All in all, I think that this has been a helpful exercise so far. I will continue to experiment and get more proficient with the thermal camera.
Buy Bodge Buster – Homeowner Air Source Heat Pump Installation Guide: https://amzn.to/3NVndlU
From Zero to Heat Pump Hero: https://amzn.to/4bWkPFb
Subscribe and follow our Homeowners’ Q&A heat pump podcast
- 22 Forums
- 2,074 Topics
- 45.5 K Posts
- 85 Online
- 3,351 Members
Join Us!
Trusted Installers
Struggling to find a reliable heat pump installer? A poor installation can lead to inefficiencies and high running costs. We now connect homeowners with top-rated installers who deliver quality work and excellent service.
✅ Verified, trusted & experienced installers
✅ Nationwide coverage expanding
✅ Special offers available
Latest Posts
-
RE: Why Your MCS-Certified Installer Might Not Be As Competent As You Think
@adisharma I'm really sorry to hear about your experi...
By JamesPa , 2 minutes ago
-
RE: 5 Star Service from Havenwise
@sheriff-fatman Good post. I am also considering Hav...
By Morgan , 4 hours ago
-
RE: Getting the best out of a heat pump - is Homely a possible answer?
@editor Cobbler’s Mantra that!
By Toodles , 5 hours ago
-
RE: What’s the modern take on advised types of insulation?
Grant was my local MP before he lost his seat. He was ...
By Jeff , 19 hours ago
-
RE: Radiators downstairs are cooler at the bottom after ASHP install
@melonbuffet This is great assuming now the down stairs...
By ASHP-BOBBA , 23 hours ago
-
RE: Commencing on an ASHP Installation Process
@jamespa Thanks for your input into this thread so far....
By Sheriff Fatman , 23 hours ago
-
Pacific Blue reveals ageing Codrington Wind Farm decommissioning plans.
Australia Blue, the first wind farm in Western Victoria...
By Morgan , 23 hours ago
-
RE: Ripped Off: How UK Homeowners Are Paying Gas Prices for Wind Energy
The challenge is who pays, who holds the debt and the i...
By Jeff , 1 day ago
-
RE: Flow rate discrepancy between ASHP and manifold
That's useful thanks, I hadn't seen that table before. ...
By AshRolls , 2 days ago
-
In principle I agree, @johnmo, but with provisos. The...
By Majordennisbloodnok , 2 days ago
-
RE: Heat pump installation and BUS Grant timings
@jamespa Thats how I understood it too. 🙂
By ASHP-BOBBA , 2 days ago
-
RE: Antifreeze top up for my heat pump - is this a rip off?
@sallyl That sounds about right if they are re-filling ...
By Brendon Uys , 2 days ago
-
RE: Enabling WiFi: Samsung ASHP on Smart Things App
I would switch it off and see if anyone noticed. We use...
By Anonymous 5011 , 3 days ago
-
I wouldn't be so sure about that. Heat pump designers ...
By JamesPa , 3 days ago
-
RE: Jokes and fun posts about heat pumps and renewables
@toodles they're a rowdy bunch!
By Mars , 3 days ago
-
RE: Home energy storage & battery register
@jamespa To a certain extent, by exporting to the grid ...
By Toodles , 4 days ago
-
RE: Forum updates, announcements & issues
@editor Fairy Nuff Mars, I doubt that my ramblings woul...
By Toodles , 5 days ago
-
RE: Confusion about heat pump sizing
We’ve published a deep dive into heat pump sizing, and ...
By Mars , 5 days ago
-
We’ve published a deep dive into heat pump sizing, and ...
By Mars , 5 days ago