Next year will see tighter requirements relating to NOx emissions from boilers to come into force. Chris Meir, Sales Director at Remeha, looks at the latest moves to improve heating efficiency levels and air quality, and how the industry can address these requirements.
Nobody likes unnecessary waste. That’s why the European Union introduced the Energy-related Products (ErP) Directive in 2015 – to encourage the replacement of less efficient products with higher efficiency heating technology. Now the EU has turned its attention to nitrogen oxides (NOx), with new mandatory requirements for space heaters set to come into force next year under ErP. Even though Brexit negotiations are underway, all EU legislation will remain in place in the UK until it formally departs in March 2019. So what does this mean for installers – and what does it mean for boilers?
New ErP requirements
In September 2015, tighter efficiencies were enforced for space heating, including boilers up to 400kW on both new build and retrofit projects under the Ecodesign Directive of ErP. In practice, the higher efficiency requirements have effectively made it mandatory to install condensing boilers on small to medium-sized projects, phasing out non-condensing boilers up to 400kW.
The one exception has been the direct, like-for-like replacement of non-condensing pressure jet boiler shells or burners. These were initially out of scope of the legislation to allow for spares provision. However, from the beginning of next year, the window of opportunity for replacing burners or shells for non-condensing pressure jet boilers below 400kW closes firmly.
Then, from 26 September 2018, maximum NOx emissions of 56mg/kWh will be enforced for gas and liquefied petroleum (LPG) gas boilers and 120mg/kWh for oil-fired boilers. As before, the legislation applies to new equipment on both new build and replacement projects.
Focus on compliance
So, how will the new legislation affect the industry? For new build projects, the focus will be on installing only ErP-compliant, EU-certified, high efficiency, low NOx heating solutions.
The same is true for refurbishment projects. But the impact is likely to be greater as like-for-like replacements may no longer be possible. The tighter ErP requirements could mean a switch of technology and/or fuel supply as necessary. A probable scenario is a move to condensing boilers operating on either gas or LPG.
The drive towards condensing boiler technology is rooted in the fact that condensing boilers are the most efficient of all boiler types. Advanced models, like the Remeha Quinta Range, are capable of achieving near maximum gross efficiencies at around 98%.
High-performing boilers like these are also engineered to meet ultra-low NOx criteria at or below 40mg/kWh. As such they meet the EU standard EN15502 Pt 1 2015 Class 6 for NOx and are future-proofed to ErP 2018 NOx requirements. At the same time they are eligible for maximum BREEAM credits under the Pol 2 pollution category, helping to contribute to a higher environmental building rating.
Many condensing boilers are also certified for operation on LPG, making them a viable solution for off-grid projects. And importantly, they are a proven, tried-and-tested solution, with some low NOx condensing boiler models now in their third or even fourth generation.
So how to achieve maximum heating performance with minimum disruption? Switching to condensing boilers can and should be a smooth process. But on refurbishment projects in particular, certain design issues – such as the condensate and flueing arrangements – might benefit from forward planning. The same is true on off-grid projects where a change of fuel source is required.
Size matters
Then there’s the sizing. Accurate sizing of the heat load will help maximise energy performance and create a more comfortable building environment. Taking time to resize the current demand is essential as the building, and how it is used, may have changed since the last boiler installation.
The next decision is the equipment. Sharing the load across two or more boilers rather than installing one higher output unit allows the boilers to operate at part load where they are most efficient. This arrangement also increases the turndown ratio and modulation capability, allowing the boilers to match the building’s flexible heat demand more closely for further energy bill and cost reductions. At the same time, a multiple-boiler design increases the reliability and lifecycle of the individual boilers while making servicing and maintenance easier.
Another factor for consideration is the dew point. Condensing boilers perform best at return temperatures at or below 54°C (the dew point) where they can recover both sensible and latent heat from the flue gases. In older buildings, the radiator circuits will typically have been designed for 82°C flow and 71°C return temperatures, which will prevent the boiler from fully condensing.
How to resolve this? One solution is to lower the flow and return temperatures to 70/50°C or even 60/40°C. This is usually possible, as radiators in older buildings are frequently oversized, especially in buildings where fabric improvements have been made since the original heating installation.
Widening the temperature differential to, say, 80°C flow and 50°C return temperatures might be another option. This will allow the condensing boilers to condense while at the same time enabling them to provide the higher-temperature water needed to heat a calorifier or plate heat exchanger.
Of course, adding the appropriate control is key to achieving the higher boiler efficiencies and keeping NOx emissions to a minimum. Upgrading to time and temperature controls will optimise boiler performance. Adding a weather compensated control helps the boilers adapt to the fluctuating demand according to the outside temperature, increasing energy savings still further. Using a sequential control with multiple boilers lengthens their lifespan, rotating the lead boiler and ensuring effective operation.
Any legislation that reduces energy use, fuel bills and greenhouse gas emissions is to be welcomed. For end users, the benefits of the tighter ErP requirements are clear – the EU predicts a 20% reduction in energy costs on refurbishment projects when upgrading to ErP-compliant equipment. Then there’s the issue of air quality. As buildings and their heating systems typically emit NOx emissions, introducing mandatory emission requirements from heating is an important step towards achieving cleaner air.
Flexibility assured
End users aside, ErP’s drive to condensing boilers can also benefit installers. Firstly, condensing boilers are lighter and more compact, making them easier to handle and install. Secondly, they are designed to be flexible, with extended options that provide compact, time-saving solutions. Remeha, for example, offers complete cascade packages for two to ten wall-hung boilers that can be put together rapidly and entirely without welding.
Finally, manufacturers now provide an increasingly wide range of boiler outputs, making it easier to match the heat load. The Remeha Quinta Range, for example, offers outputs from 30kW right up to 160kW and the opportunity for mixed output cascades to achieve maximum performance and minimum waste.
ErP 2018 is coming. Fortunately, with today’s advanced, high efficiency, ultra-low NOx condensing boilers the tighter requirements of ErP and its considerable benefits are entirely achievable. But it’s always good to be prepared.
