In the EU and UK it is now obligatory for all new domestic heating and plumbing products (rated up to 400 kw) to comply with maximum nitrogen oxide (NOx) emission levels. This is line with a great deal of international regulation: NOx emissions are controlled by law or regulation in many countries (including the US, Canada, Australia and Singapore) and these may vary further by sector (maritime and automotive may have their own specific codes and limits, for example). 

The regulation of NOx required because this gas is a major pollutant, associated with thousands of deaths worldwide through its effects – both direct and indirect – on human health. It has been associated with asthma in children, lung inflammation and a host of other respiratory disorders, as well as cardiovascular damage. NOx is dangerous to animals, plants and ecosystems and is a major constituent of acid rain and smog. 

Despite its singular name, NOx is actually a collective term for nitrogen oxides – a family of highly reactive and poisonous gases – which are produced when fossil fuels are burned. Although NOx pollution is a global problem, large cities are particularly badly affected through vehicle exhaust fumes and heating system emissions; around a third of any large city’s NOx pollution comes from heating. In addition, nitrogen dioxide reacts in sunlight with other gases (such as volatile organic compounds) to generate ozone, which is a greenhouse gas.  

Why measure NOx?

Since NOx emissions are increasingly regulated, they must be measured to ensure compliance with relevant directives. The measurement of NOx from boilers and other domestic appliances is also carried out to check that these are running safely, and to ensure the owner/operator and those around them are not being exposed to excessive NOx. 

Measuring NOx with a flue gas analyzer/combustion analyzer

As well as having to meet the demands of regulation, the HVAC sector recognises the growing importance of NOx measurement due to the worldwide focus on sustainability and green issues, and awareness of its harmful effects on health. This is reflected in a growing market for combustion analyzers that calculate NOx (e.g. the Sprint Pro 5 and the Sprint Pro 6).  

In the short to medium term, demand for NOx measurement seems likely to increase; the reduction of NOx emissions is a key component of sustainability policies worldwide and HVAC engineers and designers are prioritising the design of better, cleaner forms of heating (which will have to be benchmarked, verified and maintained).  

Over time, highly efficient, ultra-low-NOx systems are likely to dominate, and the measurement of NOx will therefore become an increasingly important parameter and a more prominent part of day-to-day work in the HVAC sector. 

Our Sprint Pro 5 and 6 models come complete with dedicated NO sensors allowing for a range of NO and NOx measurement options