Northumberland boiler installations: The Good, the Bad, and the Ugly
http://knight-ware-labs.co.uk/A-Range-Of-Fundamentals-About-Gas-Boilers-You-Did-Not-Find-Out-About-In-College-.html
This is made worse when boilers sizes are increased in order to improve hot water performance; the better the hot water performance, the higher the minimum output. They are known as being one of the most efficient