Modular boilers are designed as an alternative to large single boilers and offer an efficient, secure and flexible approach to commercial heating. Essentially comprising a number of separate small boiler modules, which can be installed alongside one another in a horizontal or as a vertical stack, modulation is shared across all modules in the system to ensure only the required amount of heat is generated.

Where floor-standing boilers have traditionally been the boiler of choice for projects requiring high heat output, they may not always be the most suitable and practical option. When it comes to retrofits in older buildings, demands may have increased over time, or the building may have had an extension.

Increasing boiler size to adequately meet the changing demands of a building could be an issue for plant rooms where space is already limited. For instance, when construction and refurbishment contractor, Mulalley & Co, needed an efficient and space-saving heating system to replace seven existing NGR floor-standing cast iron sectional boilers, it upgraded to two Wessex ModuMax modules, stacked on top of each other, with a total output of 464kW. With the previous system using up most of the floor area available, the new modular system reduced the area needed by nearly half.

Similarly, when it comes to modern commercial buildings, plant room space is often at a premium. With the priority being on floor space that generates value for money, plant rooms are often small and tucked away. To address this, modern condensing modular boilers can be positioned in a way that best suits a plantrooms layout.

Available as single boiler modules, or with the option to stack in combinations to the desired output, continuous product development over the last few decades has made it possible to achieve an output of 1MW with modular boiler systems from less than 1m² of floor space.

Compared to larger high output boilers, which may require a crane during the installation process, modular boilers can be easily separated and moved to the place of use within a building. Furthermore, thanks to their compact design, issues such as tight stairways and overhead obstructions can be avoided.

It's also worth remembering that when it comes to retrofits, modular boilers can also be installed alongside the existing boiler for a smooth changeover.

Unlike traditional boilers that operate at fixed heat outputs, modulating boilers adjust their heat output based on the current demand. This means the boilers deliver the right amount of heat, at the right time, with little or no wastage. This not only has valuable cost benefits but also makes for a low environmental impact.

To understand the full impact of this versatility, let’s consider an application that requires four 70kW non-modulating boilers that can be turned down from 280kW to 70kW in 70kW increments. If there is an off-peak demand period, requiring a constant 95kW of power to maintain a heating circuit at a set temperature, two boilers would need to run together to meet the demand. However, the plant would then produce 140kW, which is 45kW more than necessary. In comparison, three 97kW Wessex ModuMax 97/291V units could be installed as an alternative to four non-modulating 70kW models; together, at 291kW, these would satisfy the 280kW peak load requirement. However, as boilers run most efficiently at lowest loads, this 95kW requirement could be efficiently achieved by firing two or three Wessex ModuMax boilers and modulating these together to achieve the desired power for example, three boilers, each running at 31.6kW each.

This would also reduce the inefficiencies of short cycling, which can lead to not just energy waste but more worryingly, wear and tear, which could eventually result in boiler breakdown.

To further enhance the longevity of modular boilers, it’s also important to specify a product with a stainless-steel heat exchanger. This will offer increased resistance against corrosion. Also, as stainless-steel heat exchangers can withstand a higher flow rate than exchangers made from other materials, the risk of blockages within the exchanger from debris or rust will also be minimized.

Despite all the best will in the world, things can and still do go wrong and this is where modular boilers offer increased protection. With a modular boiler system, there’s the added benefit of system back up. Should one boiler module need servicing or stop working, the other modules in the system can continue to meet the system demand for heat without the risk of interruption to services.

With the constant battle to achieve more with less in today’s world, modular boilers provide a flexible and energy-efficient solution. Designed to accurately match the heat load profile of a building, with minimal risk of costly disruption and unplanned downtime, modern modular boilers offer a durable and cost-effective solution for commercial buildings. Moreover, thanks to their considerably reduced footprint and low CO2 and NOx emissions, they successfully reduce the space needed for equipment in a plantroom, while lowering impact on the environment.