Fitting Big Heating Performance into Smaller Spaces

Energy efficiency and performance do not have to be compromised if the plant room is tight on space or access is limited, as Jonathan Grist, commercial director of Viessmann explains.

Recently published government papers such as the Clean Growth and Clean Air strategy are creating a major shift towards low NOx appliances. Smaller wall-mounted or floor standing condensing boilers are already equipped with low NOx pre-mix burners. However, when it comes to larger heat generators, many energy managers and their contractors, particularly those in larger cities, experience the frustration of having to identify the preferred central heating boiler for their premises, while meeting the latest NOx emissions. Boilers with a heat output of more than 600 kW have in most cases traditionally been equipped with jet burners which are “matched” for performance, with the appropriate boiler. But today, it is not always possible to go down this route while providing a low NOx solution.

An additional headache has been that large boilers with third party jet burners just won’t fit in existing plant rooms. Modernising the boiler is an opportunity to improve energy efficiency and reduce running costs, but if the plant room is tight on space or access to the room is narrow at any point, boiler choice can be limited and potential savings lost. This is happening increasingly often because large industrial plantrooms are going out of favour and are being replaced by multiple boiler rooms with smaller spaces. Now there is a new solution to this headache.

Real-life problems posed by smaller spaces and limited access have been addressed with new, patented technologies by Viessmann, the leading international heating systems manufacturer. The result is a new gas condensing commercial boiler, the Vitocrossal 200 CRU, which produces 800 to 1,000 kW, within the smallest footprint on the market for a single, high water content modular boiler. It is 27 per cent more compact than its predecessor, thanks to an innovative burner and a clever modular design which allows delivery of the heat exchanger and burner modules in two separable pieces, rather than one much larger one.

The Vitocrossal 200 CRU’s new MatriX premix gas burner is much flatter than a conventional cylindrical burner and achieves powerful performance with a shorter flame, which allows a smaller combustion chamber. These innovations have cut a full metre from the boiler’s length. For heating larger premises with large plant rooms, there is a cascade function for up to eight boilers with a total output of 8,000 kW.

Whereas “traditional” pre-mix burners are made of stainless steel and shaped like a cylindrical tube, the Vitocrossal’s CRU disc burner is constructed of sintered and drilled stainless steel mesh. The perforated structure enables very low pressure-drop across the burner material, allowing the combustion chamber to be compact. In addition, this 95 per cent porous material produces stable combustion and achieves a high output at a low flame temperature, which also helps make the burner smaller.

Another technical advancement is the extended modulation range of 1:6, which enables greater energy efficiency at partial load and low NOx emissions of less than 24 mg per kWh. Buildings have variable heating loads throughout the year, and lack of boiler control or oversizing the heat generator can cause a boiler to start/stop too frequently. This never-ending burner cycle reduces system efficiency and increase NOx emissions. The new Vitocrossal’s CRU modulation range and high water-content prevent this, reducing mechanical wear and tear and improving energy efficiency and keep NOx down.

For high operational reliability and long service life, the Vitocrossal 200 CRU employs Viessmann’s proven, corrosion-resistant stainless-steel Inox-Crossal heat exchanger. This enables highly effective heat transfer and a high condensation rate, as well as reducing maintenance requirements because the smooth stainless-steel surface has a self-cleaning effect. Efficiency is further enhanced by the boiler having two return connections, so that there can be low- and high-temperature circuits for better boiler condensation and energy efficiency. This is highly desirable where two different return temperatures come back to a boiler which is heating two different system types, for example where there is underfloor heating in one part of the building and traditional radiators in another.

Better still, there is the capability to control multiple zones in buildings, which is like having a mini BMS system at a fraction of the cost. The boiler can be connected directly to Viessmann’s Vitodata server using proven Vitocom (LAN) interfaces and has integrated WLAN for a service interface. Operating status of the heating centre is monitored around-the-clock and if a fault begins to develop the boiler will automatically send a message to the heating contractor’s smartphone. This can be a great advantage, allowing potential faults to be addressed without any interruption to daily business.

The greatest advantage of all, however, must be that plant rooms with tight space or limited access no longer have to miss out on best-in-class boiler characteristics. If you’re looking for a high- performance boiler with exceptional energy efficiency, low NOx emissions, and minimal downtime and maintenance costs, it’s worth knowing that a relatively compact boiler now delivers these big benefits.