BSEE


mproving air quality has been a commonly addressed topic in recent years for the UK, with increasing awareness of the implications of pollution on the environment and people’s health. In particular, nitrogen oxide (NOx) emissions, which are formed in a boiler’s combustion process, have been highlighted as a key pollutant that needs to be reduced where possible and legislation has been put in place to do so.


I Legislative requirements


Following the launch of the government’s Clean Air Strategy and its crucial oversight of NOx emissions from commercial boilers, Andy Green, technical director at Poerton Commercial, outlines the current legislave requirements to reduce NOx


emissions and how the commercial HVAC sector should connue to implement change


Last year was a positive one for legislative enforcement in this area. In July, the ‘Cleaner Heat Cashback’ initiative was launched to improve London’s air quality by incentivising London-based SMEs to install new and cleaner heating systems in place of old inefficient boilers. The £10 million scheme launched by Mayor Sadiq Khan offers 30-40 per cent cashback and has been well received. As of September, the Energy-related Products Directive (ErP) has set out maximum nitrogen oxide (NOx) emissions from heating systems of up to 400kW in size as part of its target to reduce energy consumption and greenhouse gas emissions by 20 per cent as of the year 2020. For oil-fired boilers, these maximum levels are 120mg/kWh and for gas or LPG boilers the restriction is 56mg/kWh.


In addition, compliance dates for the Medium Combustion Plant Directive (MCPD) have started to come into effect for new and existing combustion plants with a thermal input between 1MW and 50MW. For example, as of December 2018, new plants of this size with natural gas boilers must meet a maximum NOx emission level of 100mg/Nm3. Existing plant operators have significantly longer to comply. January 2025 will be the key date for existing plants of 5MW or higher and January 2030 will be the compliance date for those with a thermal input of between 1MW and 5MW. Most recently, we’ve seen the introduction of the government’s Clean Air Strategy which sets an ambitious, long-term target to reduce air pollution and people’s exposure to particulate matter (PM). However, while the strategy is right in pointing towards the likes of transport and industrial processes as key contributors to NOx emissions in the UK, it fails to address the NOx emissions from gas- fired boilers. What’s more, given the success of the Cleaner Heat Cashback scheme, and that it operates on a first-come-first-served basis, the Clean Air Strategy would have been the fitting follow-up to continue the momentum of reducing NOx emissions from gas boilers.


The manufacturer’s role


When it comes to meeting NOx requirements, boiler and burner manufacturers are responsible for improving their systems with combustion control techniques such as burner modifications and flue gas recirculation to reduce NOx levels. For example, the Potterton Commercial


16 BUILDING SERVICES & ENVIRONMENTAL ENGINEER AUGUST 2019 uThe commercial heang sector needs to connue to educate its customers on the importance and benefits of low NOx heang soluons


Sirius three range of stainless steel floor standing and wall-hung commercial boilers, available in outputs from 50 to 250kW, offers NOx emissions as low as 17mg/kW for maximum BREEAM credits. This is thanks to Sermeta bluejet burners, which have a three- dimensional surface to provide excellent flame retention both at boiler start-up and in extreme conditions such as in intense cold. This flame stability makes it possible to work on a wider CO2 adjustment range and thus reduce NOx and CO emissions by up to 50 per cent.


Switching to alternative, cleaner fuels is another method of reducing NOx. With the potential introduction of hydrogen into the gas network as a future fuel source for HVAC systems, manufacturers need to consider how they can ensure optimum boiler performance while catering for subsequent changes in gas quality. For example, understanding how low NOx will affect efficiency, turndown and capacity is important along with the development of gas-adapted controls. While the onus is on manufacturers to ensure new heating systems comply with maximum NOx levels, it is important for end-users to be aware of upcoming legislative changes. As such, the commercial heating sector needs to continue to educate its customers on the importance and benefits of low NOx heating solutions in the drive to improve air quality and make boilers more efficient and environmentally friendly.


More information


For more information on Potterton Commercial’s new Sirius three range of ErP compliant wall-hung and floor standing boilers with NOx levels as low as 17mg/kW, please visit www.pottertoncommercial.co.uk/ getsirius


HEATING & PLUMBING


Keeping it clean: Condensing NOx emissions in the commercial heating sector


uThe Poerton Commercial Sirius three range of stainless steel floor standing and wall hung commercial boilers, oer NOx emissions as low as 17mg/kW for maximum BREEAM credits


About Potterton Commercial


otterton Commercial, part of Baxi Heating, develops and manufactures a comprehensive range of gas and oil-fired boilers for commercial applications in the UK. With a heritage that


P


spans 150 years, Potterton Commercial continues to develop high efficiency boilers with condensing outputs from 30kW to 1MW and pressure jet outputs from 419 to 4000kW.


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