The market moves to high efficiency

Representing the capabilities of modern boilers is Ideal’s Imax range. They are available as wall-hung and floor-standing versions with outputs up to 280 kW. All models can modulate down to 12 kW, enabling boiler output to be matched to system requirements.
Developing regulations are driving changes in the boilers market. GRAHAM WILLIAMSON considers their implications and offers practical advice on product selection.As we write this article, the final decision on the future of the Building Regulations L2 and L2a for non-domestic buildings is still being debated. The proposals introduce tougher seasonal-efficiency targets for heating equipment in non-domestic properties, which will inevitably focus the industry’s attention on improving the performance of boilers and, more importantly, buildings. Whatever the outcome of this final consultation, what cannot be ignored is how high-efficiency boilers have enjoyed a significant surge in the last five years. The market share of these boilers in the UK now stands at nearly 40% of all boilers installed. Potential impact Specifiers and heating contractors need to be aware, not only of the potential impact of the legislation, but also the product options available for this increasingly popular choice. To date, the increase in the take-up of condensing boilers in the commercial sector has largely been due to product attributes, and not necessarily related to the higher operating efficiency of the equipment. Government measures, such as the Carbon Trust’s Enhanced Capital Allowance Scheme, have helped raise awareness of the benefits of condensing boilers in the commercial sector — although much education is still required. The last year alone has seen the market in the UK for commercial condensing boilers grow nearly 20%, in an otherwise flat market. This recent shift has been fuelled by innovation in the size of the boilers, ease-of-installation and siting, as well as flue flexibility. Gathering pace Clearly the move towards higher efficiency products is gathering pace and will continue to do so. However, each application must be considered in its own right, and there probably will not be one solution that fits all. Correct product selection will still be essential if real fuel savings and actual carbon reductions are to be realised, and this is recognised in the new document. For example, the use of standard-efficiency boilers in the replacement sector will continue, albeit on the proviso that heating load assessments are carried out and control upgrades are considered — therefore demonstrating a significant improvement over the older system. Where the selection of a condensing boiler is considered, this will require both system design and controls to be integrated to provide the ability for lower return temperatures to gain maximum benefit. Without a correctly designed system, a condensing boiler may only operate as efficiently as a standard boiler. It should also be recognised that a boiler will only condense when the system allows it to do so. Crucially, this is when the return temperature is maintained below 50°C. At present, few existing systems have been designed, or are even suitable, for condensing operation. These are the key issues that need to be considered if the full benefits of condensing boilers are to be realised, especially in replacement applications, which now equates to over 70% of all boilers installed. Replacement There are further issues when considering a condensing boiler in a replacement application if budgets are limited. In older systems, there is likely to be a significant build up of sludge and debris developed over time. Modern condensing heat-exchanger technology, through its compact design, is less likely to be tolerant to these conditions, and the system may have to be cleaned prior to fitting the new boiler plant. Also most condensing boilers require a greater flow rate through the boiler to maximise performance and prevent damage to the heat exchanger. An existing system in the UK is typically designed with an 11 K difference between flow and return, whereas most condensing boilers require a 20 K difference. The duty of the existing pump will thus need to be verified, and new pumps may need to be fitted. This increased differential can have an adverse effect on radiator performance. An existing installation will already have a flue system that may well have been installed for a number of years and therefore may not be suitable for the newer condensing boiler. In particular the flue system may not be able to handle the level of condensate that may be produced within it. Commitment The Government’s commitment to tackling carbon emissions will undoubtedly drive further growth in the condensing-boiler market. The impending changes to the Building Regulations will further force this change, although the debate on condensing technology will not end there as the commercial market is inherently more complicated than its domestic counterpart. Specifiers and installers will need to be aware of this debate as well as the product attributes of high-efficiency technology. Condensing boilers can offer significant benefits, but all the implications of fitting them must be considered before carrying out the installation. They must not be seen as a solution for all applications. Graham Williamson is with Ideal Boilers Ltd, PO Box 103, National Avenue, Hull HU5 4JN.
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