In a new study to determine the most user-friendly boiler manuals in the UK, those from Ideal Heating were found to be the easiest to read. That’s according to new research by Uswitch.com, which used the Flesch reading ease test to investigate 130 manuals from the UK’s ten most popular boiler manufacturers.
The study took into account the number of long sentences and length of words (by syllable) used within the manuals to determine their level of comprehension. This helped determine the rank of boiler manufacturers with the most understandable manual (shorter sentences and fewer syllables per word).
| Boiler Manufacturer | Flesch reading ease test score (Out of 100) | |
| 1 | Ideal Heating | 61.40 |
| 2 | Alpha | 60.59 |
| 3 | Intergas | 60.07 |
| 4 | Vaillant | 59.71 |
| 5 | Baxi | 59.63 |
| 6 | Worcester | 58.82 |
| 7 | Glow-worm | 58.35 |
| 8 | Viessmann | 56.06 |
| 9 | Vokera | 54.93 |
| 10 | Atag | 53.35 |
The instllation and service manuals from Ideal Heating came out on top, with a 61.40/100 score for readability, because they were made up of the fewest long sentences and shortest words (by syllable). Instructions from this boiler manufacturer were dubbed the most easily read by users.
Following in close second is the manufacturer Alpha scoring 60.59/100 for readability. Alpha’s customers said they were comfortable using their manufacturer’s manual – with 37% confident using it to fix an issue with their boiler. This is twice more than Baxi’s customers (19.7%), which ranks fifth with a manual readability of 59.63 out of 100.
Ranking third is Intergas, with a readability score of 60.07 out of 100, followed by Vaillant (59.71/100). Two in five (41%) of Vaillant’s customers agree that the manuals from the boiler manufacturer are easy and simple to understand.
Those who own a boiler from Atag may struggle the most in understanding its manual instructions, as they have the longest sentences and most complex words. Scoring just 53.35 out of 100, Atag’s boiler manuals are ranked the lowest for readability of all manufacturers studied.
Ben Gallizzi, boiler expert at Uswitch.com, offers advice on how to troubleshoot common boiler problems:
“Our survey revealed that on average 1 in 4 Brits feel confident in tackling their boiler issues themselves. While some problems require professional assistance, others can be fixed by consulting your manufacturer’s manual. Here are some tips from our guide on how to troubleshoot common boiler problems.
Check your manual – The instruction manual provided by your boiler manufacturer is often the first step to resolving an issue. If there is an error code displayed on your boiler, check what the corresponding issue is to identify the exact issue you should target.
Check your pipes – As we enter the colder months, frozen outdoor pipes can often lead to no heating as no water is reaching the boiler. If your condensate pipe is frozen, heat the area with some warm water (not boiling), or apply heat to the pipe with a hairdryer or electric blanket.
Check your thermostat – If the thermostat is disconnected from the boiler, it can also be an obstacle to getting heating in your home. Try nudging your thermostat up a few degrees to kickstart it into action. Also check if any switches have been knocked out of place. If the problem persists, try resetting the thermostat following manufacturer instructions.
Check your boiler pressure – If your boiler pressure is too high or too low, both can create leaks in the system that prevent your boiler from running efficiently. To resolve this first check your boiler’s pressure gauge. If an issue is detected, follow your boiler instruction manual to repressurise the system.”
Read the full study on boiler statistics to find out more.

