Boiler replacement — be prepared

boiler, DHW, Ideal Commercial, space heating
The future is condensing boilers - Darren Finley

Darren Finley of Ideal Commercial outlines the advantages of installing high-efficiency condensing commercial boilers ahead of legislation changes — as well as some of the aspects that must be considered when designing a replacement system.

The ErP (Energy-related Products) Directive is expected to come into force in 2015. Within this documentation, the European Commission has outlined a minimum efficiency requirement for individual energy-using appliances. In the case of space-heating boilers, the new legislation will effectively see the phasing out of all non-condensing models so that conducting a like-for-like replacement utilising low-efficiency boilers will no longer be an option.

As retrofit projects account for around 70% of the boiler market, the industry has no choice but to get up to speed on the implications of replacing a non-condensing boiler with a high-efficiency condensing model to ensure compliance with legislative requirements.

From a practical viewpoint, as well as an environmental one, modern condensing boilers offer numerous advantages compared to older appliances.

Leading manufacturers have developed products that not only exceed the required efficiency standards, including those outlined in the forthcoming ErP Directive, but that also offer much smaller footprints, higher outputs for wall-hung models, innovative design for quick and easy maintenance, module sequencing for longevity and far more advanced control systems — including simple integration with a building-management system.

In addition to offering these improved features and reducing fuel bills, other financial advantages are available if, for instance, the appliance is listed on the Energy Technology List (ETL). This lets businesses claim a 100% first-year capital allowance on qualifying machinery as part of the Government’s Enhanced Capital Allowance scheme.

Carbon saving — these two Imax Xtra 480 gas-fired condensing boilers from Ideal Commercial at the new Langtree Park stadium of St Helens Rugby Football Club work alongside a biomass boiler.

There is little doubt that the potential of condensing boilers to save cost, space and carbon make them a sensible choice for boiler replacement — even before the new efficiency standards are enforced. However, there are a number of important aspects to consider when integrating a condensing boiler with an existing space-heating system.

One of the most common queries boiler manufacturers receive is whether the existing space-heating system can accommodate the difference in flow and return temperatures required for the new boiler to operate in condensing mode. The rule of thumb is that the lower the return temperature, the more efficient the operation of the boiler, though for significant condensation to form in the heat exchanger, the return temperature must be at 54°C or lower. Even if the new boiler is not operating in full condensing mode for some periods of the year, it will still be significantly more energy efficient than standard-efficiency models. However, with good preparation and intelligent design, the boiler’s maximum efficiency potential can be realised in most cases.

The vital first step when designing a replacement heating system is to conduct an in-depth survey of the building.

Depending on its age, there are likely to have been a number of modifications made since the building’s initial construction, often consisting of upgrades to the building fabric such as improved insulation, building extensions, division of rooms, adaptations to the number of radiators, or the replacement of pipework.

The needs of the building will also need to be reassessed, as the hours of occupation may have changed. Without a proper site survey, modifications made to the building since its initial construction could be overlooked, affecting vital calculations such as those made to establish heat loss, heat gain, humidity and air flow that are used in the sizing of a space-heating system.

Another essential step is to ensure the existing system is fully cleansed and flushed before any new appliances are installed. This removes any debris as well as mineral deposits such as iron oxide and limescale, which can cause corrosion and reduce the lifespan of boiler components.

The advanced control systems of modern boilers include simple integration with a building-management system.

There are various methods of removing corrosive minerals and debris from a heating system — including chemical cleaners, pumps and magnets. The best cleaning method will depend on the system, such as the nature and severity of the contamination, whether it is a sealed system or not, if there have been any existing issues etc.

Regular system cleaning, in addition to annual boiler servicing, is an important part of ensuring that the boiler’s operational potential is maximised.

In addition, the new boiler can be separated from the existing system using a plate heat exchanger, ensuring the boiler remains uncontaminated and working at optimum efficiency in the years to come.

There are various methods the design engineer can explore to reduce the return temperature and maximise boiler efficiency, and these depend on the exact specifications of a particular application. At any point, the boiler manufacturer is always on hand to assist in the design and maintenance of a space-heating system. For added peace of mind, it is best to work with a company that offers extended warranties on parts and labour.

As with any technical system, knowledge is key, and a reliable manufacturer is well placed to work alongside the design engineer, providing technical and product advice at any stage of the process, as well as further recommendations that can improve heating system efficiency still further.

Darren Finley is national sales director for Ideal Commercial.

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