Radiators-Leaks

Cleaning radiators is an important part of maintaining an efficient, reliable central heating system and power flushing provides a speedy, thorough method of clearing out corrosion and other debris from the system. Part L of the UK Building Regulations even requires that systems are cleaned and flushed before adding anti-corrosion chemicals during commissioning whilst the warranty of new boilers often depends on correct cleaning and flushing. Thermal imaging provides a great, quantitative method of checking the performance of a heating system before and after flushing, thereby confirming the efficacy of the flushing process and visualising the results for the customer.

Choosing the Right Thermal Imaging Camera

With temperature readings falling within the normal operating range of all our thermal cameras, the most important issues to consider are thermal sensitivity and resolution. A thermal resolution of 80 x 60 pixels should be sufficient as checking radiators does not require a high-resolution imager. Similarly, a thermal sensitivity of 100mK would also be suitable, especially as temperature variations caused by sludge or other debris tend to be very clear, especially when a camera with an auto ranging function. Suitable models include the FLIR C5 or E4 Wifi and you can view our entire comprehensive range at Thermal Imaging Camera page. We also have an extensive hire fleet, providing an additional cost-effective solution with units available from £95 for three-day hire.

Pre-Flush Inspection

Domestic central heating boilers typically have an outflow temperature of around 75˚C and this would normally translate to a surface temperature of 55˚C to 60˚C on radiators in good condition. When checking whether flushing is required, it is important to look for lower temperatures than expected on any part of the radiator, especially for cold spots or patches. In order to best depict the heat pattern, it is advised to turn on the system in plenty of time and make sure all radiators are turned up as high as possible.

Corrosion usually causes cold spots at the bottom of a radiator, as shown in Figure 1 where a significant amount of sludge has collected in the bottom of a radiator. Note the difference in colour between points M1 and M2 compared to point M3, which indicates a temperature difference of approximately 22˚C.

Figure 1

Testo-power-flushing-before

Similarly, Figure 2 shows another radiator where corrosion is centred around the right-hand side of the radiator at the base. The dark blue/purple colour at point M2 indicates a temperature of just under 30˚C whilst points M1 and M3 have a temperature of approximately 50˚C, as shown by the orange hue.

Figure 2

Testo-power-flushing-before-extra

It is important to remember that these examples show particularly extensive corrosion and deposit build up inside the radiators and that less extreme cases without such a wide variation in temperature may also show a system that requires power flushing. Nevertheless, this provides a useful indication of what to look out for when assessing whether it is necessary to power flush a central heating system.

Post-Flush Inspection

During the flushing process, a thermal camera can be used to monitor progress and make sure that deposits are being successfully removed as the blue/purple colours seen in Figures 1 and 2 make way for brighter yellows or oranges (when using the ‘hot iron’ colour palette).

Once power flushing has been completed, the user should see a more or less uniform colour across the radiator, without the telltale cold patches caused by corrosion and debris. Remember that uniformity is more important than the actual temperature value when it comes to seeing the results of the flush. In Figure 3 - the post-flush version of Figure 1 - see how the colour at M1, M2 and M3 is now a broadly similar shade of yellow, clearly showing the debris that caused the cold spot before flushing has been successfully removed.

Figure 3

Testo-power-flushing-after

Similarly, Figure 4 also shows a consistent yellow across the radiator, thus indicating a clean, efficient system. It is also noticeable in this example that the overall temperature of the radiator has increased, as shown by the brighter yellow at points M1 and M2 compared to the orange in Figure 1.

Figure 4

Testo-power-flushing-after-extra

By checking the effects of a power flush with thermal imaging technology, technicians and heating engineers can make doubly sure that a central heating system has been thoroughly cleaned. Not only does this provide peace of mind for the operator themselves, it also allows them to show clients the results of their work and even help convince of the need for power flushing in the first place. Thermal technology stands out as the only way to provide a comprehensive, visual, and quantitative assessment of the efficacy of central heating power flushing.