Commercial heating


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Raising the bar to lower emissions


Replacing outdated commercial boilers with modern, high-efficiency condensing models is an excellent method of achieving significant energy savings, as well as a reducing in CO and NOx emissions – as Emiliano Gabrielli, country manager at ATAG Commercial, explains


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pace heating and hot water in commercial and industrial properties accounts for more than a quarter of the UK’s heating demand. According


to the National Atmospheric Emissions Inventory (NAEI), CO2 emissions were at 85 MtCO2 in 2019, with commercial buildings accounting for 14% of these and public buildings 9%. Prior to the pandemic, UK government findings highlighted a 3% decrease in emissions in the business sector, attributed to a reduction in industrial combustion and air conditioning. But now, as the commercial heating industry looks towards decarbonisation and a Net Zero future, it is important to make the most of existing high efficiency products. When looking to replace commercial boilers as part of a refurbishment or retrofit project, it is important to consider the long-term economic and energy efficient credentials of any new heating products or systems. Considering the advances in engineering and technology, there are many options now available to contractors and engineers. So, what are the key things to look out for when replacing outdated, inefficient appliances? The three core elements to consider are the heat


exchanger, pump and controls, each of which helps in terms of longevity and efficiency. Let’s consider each of these individually, beginning with the heat exchanger, which can maximise heat transfer without compromising reliability.


When identifying the best heat exchanger for the


application in hand, the material from which this vital component is made is significant. Indeed, ensuring the heat exchanger is constructed from stainless steel not only assists reliability, it also enhances direct heat transfer and levels of condensation. Additionally, stainless steel has unique properties enabling it to remain smooth, despite the presence of sulphuric and nitric acid in the water (created from flue gas condensate). In fact, stainless steel can neutralise any corrosive effect and sustain a longer lasting, higher level of operational efficiency when compared to alternative materials. However, stainless steel construction alone is not enough; modern heat exchangers have been designed to maximise the transfer of thermal energy from the boiler’s burner into the system water. This


12 November 2021


process is dependent upon the water’s turbulence and flow rate, which leads to the second piece of the commercial heating puzzle – the pump. A modulating circulation pump is essential in


keeping the water inside the heat exchanger in a turbulent state. This turbulence agitates the waterflow, removing any insulating barrier between the water and the wall of the heat exchanger – thereby ensuring a rapid and efficient transfer of heat. Due to the pump moving water around inside a


small closed system (between the boiler and the low loss header or heat exchanger, depending of the application), it expends minimal energy; furthermore, the turbulent flow of the water preserves the lifespan of the heat exchanger by reducing debris and precipitation fouling on the heat transfer surface. The latest light commercial boilers, such as ATAG’s


XL-W and XL-F, utilise intelligent built-in, modulating pumps to constantly monitor flow rate. This allows the heat exchanger to reach and maintain a set-point temperature, while minimising energy input. From an energy saving standpoint, a boiler’s


overall modulation, or turndown, needs to be considered, particularly as heating requirements vary depending upon the seasons – with more warmth needed during the winter months, for example. Utilising a boiler with a wide modulation ratio will not only enhance efficiency, it will also reduce wear and tear on components. The modulation ratio indicates a boiler’s ability to reduce its maximum output


to its minimum output – and the wider the range, the better. As a result, units achieving 1:10 (when minimum output is one tenth of the maximum) are considered to have an excellent modulation ratio. Finally, a boiler and heating system’s efficiency is


bolstered by the controls utilised, which need to be advanced enough to manage the heating demand. Astute manufacturers will have integrated these into their boilers, removing the need for any external devices, while still ensuring they can be connected with any BMS if necessary – through common protocols such as ModBUS and BACnet. One aspect of a boiler that should never be


overlooked is its exhaust gases – particularly in terms of NOx emissions. Units with specially designed combustion zones inside the heat exchanger will greatly minimise the formation of harmful NOx and CO. Indeed, the NOx levels for all our XL-F boilers are below 24mg/kWh (EN15502) and achieve the maximum BREEAM credits in accordance with the BREEAM UK New Construction 2018. So, as the commercial heating sector looks


towards a zero-carbon future, manufacturers are playing their part by ensuring their boilers are capable of reducing emissions while offering reliable, effective and long-lasting levels of performance. By selecting modern, technological advanced models equipped with the latest components, installers and contractors can ensure every project excels, both in terms of energy efficiency and durability.


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