BSEE O
Building services engineers are increasingly turning to modular boiler designs to achieve the ghter environmental requirements surrounding heat. Good boiler selecon can play a key role in maximising the benefits, says Ryan Kirkwood, specificaon manager at Remeha
ver the last century, boiler technology has evolved
dramatically from the earliest
manufactured ‘tea kettle’ commercial boilers to today’s precision engineered condensing boilers. More compact and lightweight, modern condensing boilers are capable of delivering near maximum efficiency with low Class 6 emission levels and enhanced control capability as standard.
But it’s how this high efficiency technology is applied that will determine the end result. One flexible solution that optimises both plant room space and boiler lifetime performance is a modular boiler design.
How does this benefit the customer and building services engineer? Essentially, a modular boiler arrangement enables the design to be broken down into smaller parts or sections for easier integration and improved efficiency.
With that in mind, let’s consider two frequent challenges when it comes to heating refurbishment: space and capital costs.
Space constraints
The plant room in older buildings is often a cramped, low-ceilinged basement space, accessed via a narrow staircase. So, the first hurdle is typically how to get the boilers out and the new boilers into the plant room.
Historically, large boilers with a high output would be specified to meet a high heat demand – as a site visit to an older school, hotel or hospital building will reveal. This was due in part to a limited range of boilers but also to combat poor insulation, infiltration losses and general inefficiencies in the system. When replacing dated boiler plant with new-generation condensing boilers, a key advantage of a modular configuration is the ability to install large outputs in a much smaller footprint as well as in hard-to- reach areas.
Selecting several lower output condensing boilers, which are proportionally more compact in size, to meet the demand is a practical means of overcoming access and space constraints. Installation time and costs are also reduced as the smaller, more lightweight units are both safer to handle and easier to position. Boilers like the Remeha floor standing range, for example, are designed to fit through standard doorways and lifts, with integral wheels for easier manoeuvrability. Some higher output boilers are also able to be disassembled into parts, which can again smooth access constraints and help avoid associated costs such as the need for cranes. These same design aspects enable the plant to be removed safely from the building at the end of its lifecycle.
Efficient by design
A further benefit of a modular boiler arrangement is that it enables more accurate matching of the changing heat requirements of the building. In many commercial and non- domestic buildings, the heat requirement will vary throughout the day depending on occupancy and usage. If the boilers are able to adapt quickly and accurately to the fluctuating demand, this will keep comfort levels high while avoiding energy waste.
As the design increases the turndown ratio, the boilers can match the lower demand while still providing the load required by the system at peak demand. This in turn prevents on/off cycling for more efficient energy use.
A multi-boiler design will also provide improved reliability and non- disruptive maintenance, ensuring uninterrupted heating provision even if one of the boilers is offline.
Floorstanding or vertical stacking?
Now let’s consider how the plant space is best allocated.
Modular boiler arrangements are normally separated into stacking and
BOILERS & HOT WATER Evolving the design
floor standing categories. With both, maintenance areas, access space and walkways must be factored in when selecting the boilers. A major advantage of vertical- stacking style arrangements is their ability to offer a larger heat output in a smaller physical footprint. But as access is required on all sides of the plant and pipework arrangement, the units will often need to be positioned as an island in the middle of the plant room. The vertical headers combining the units will also need careful attention to ensure that the boiler pumps, system pumps and overall hydronics perform as intended. Floor standing modular
configurations, in contrast, usually only require access at the front. So, while the footprint might be similar in terms of plant, they can achieve an equally, if not more, compact configuration overall. As a result, there is greater plant room design flexibility and, as the modules are all at the same height, maintenance can be carried out safely at a lower level.
Good boiler selection
Boiler selection is the next step. Regardless of the design, with all modern condensing boilers, quality construction and longevity should top the list of criteria.
The heat exchanger is central to this, as many floor standing boiler arrangements and most vertical stacking systems use aluminium heat exchangers to keep weight down and efficiency up.
When selecting boilers for a modular system, check if the heat exchanger is sectional or monobloc. A single casting monobloc design will allow constant thermal expansion across the whole heat exchanger, reducing the need for large joins and improving
performance, reliability and lifespan. An understanding of how the connecting pipe kit holds up to the overall job specification, with quality parts, pumps and valves, is advisable. The products, accessories and spare parts should also be readily available to ensure a timely delivery and high heating performance throughout the boiler’s life cycle.
uA key advantage of a modular boiler configuraon is the ability to install large outputs in a much smaller footprint as well as in hardtoreach areas
Finally, if the plant is to continue to operate efficiently throughout its lifecycle, ease of installation, control, maintenance and servicing should also be determining factors when it comes to boiler selection.
Quality outcome
As an industry, our aim is to deliver comfortable, energy-efficient buildings, with heating a natural starting point for improvement measures that will move us closer to our more challenging environmental targets.
Modular boiler designs can provide a time saving, space-saving, energy- efficient solution to high
performance heating. But as each project will have different requirements and budgets, it’s essential to think carefully about how best to allocate plant space and to ensure good boiler selection to achieve the best outcome. And with manufacturers like Remeha offering expert product and technical support, we as an industry can work towards achieving the most appropriate, cost-effective and energy-efficient solution every time.
remeha.co.uk
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COMMERCIAL & INDUSTRIAL
20 BUILDING SERVICES & ENVIRONMENTAL ENGINEER NOVEMBER 2019
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