To repair or replace?
Wall-hung condensing boilers with flexible flueing are growing in popularity.
Upgrading heating plant and installing a new boiler is a major purchase for organisations. GRAHAM WILLIAMSOn looks at why, despite the initial outlay, it is better to replace rather than continue to repair ailing heating plant.The ever-increasing pressure on businesses to take greater responsibility for budgets and reduce costs means that there are always difficult decisions to be made. When it comes to whether to replace or simply repair an older heating plant, these pressures intensify as current and pending changes to legislation, in particular the Building Regulations, continue to require organisations to demonstrate a more energy-efficient approach. In many cases, it will be obvious that the time has come to make the much-needed investment in a more efficient boiler, rather than continuing to eke out a few more years of costly service from an existing appliance. False economy
For other installations the choice may be less stark, and the temptation will remain to postpone major capital expenditure. However, this could turn out to be a false economy. Where boilers are concerned, it makes greater sense to take a planned approach rather than having to make a distress and potentially costly purchase when the boiler fails, which could also have implications for the smooth running of a modern business. In operation, older conventional boilers can be 50% more demanding on fuel than modern condensing or high-efficiency equivalents and are equally expensive to maintain. Although not often visible, such heightened running costs will invariably lead to a much greater financial burden on organisations in the long-term. Once the decision has been made to replace rather than repair, building owners are generally faced by a bewildering plethora of boiler types, output and initial purchase prices. To choose between these options, some clients may take their lead from the contractor, while other larger property owners may have dedicated consultant specifiers. Some organisations may delegate the task to someone within the business who will not necessarily have a technical background in heating systems. In this situation it is important to ensure that the choice of boiler is not simply made on the initial purchase cost and that all the benefits of both condensing and high efficiency technologies are taken into consideration. Condensing boilers
The move towards using condensing boilers is being increasingly driven by the Government. Last year’s Energy White Paper set out a number of initiatives to meet the reduction of carbon-dioxide emissions as agreed at Kyoto. These included ensuring both domestic and commercial buildings are as energy efficient as possible. This reinforces an EU Directive to improve the Energy Performance of Buildings and which has to be implemented by member states by 1 January 2006. By its very nature, a condensing boiler recovers heat from the products of combustion (flue gases) causing the flue-gas temperature to fall below its dew point and deposit condensate. There are further environmental benefits when a condensing boiler is operating at optimum efficiency — such as reduced time in-use, lower fuel demands and consequentially less damaging emissions. Even in non-condensing mode, a condensing boiler will be more efficient than conventional alternatives installed in the same system, by virtue of the greater surface area of its heat exchanger. However, when operating at full capacity, condensing boilers can help organisations to realise significant energy savings. This is largely due to the use of two heat exchangers. The secondary heat exchanger takes advantage of flue gases to pre-heat returning water and as a result gives the boiler the potential to return energy efficiency levels of up to an impressive 94%. Wall-hung boilers
Another possible approach for organisations looking for a new boiler is the increasingly popular wall-hung condensing boiler with a compact 2-stage heat exchanger. By making maximum use of aluminium components and drawing on the best of boiler technology, the result is an attractive and very compact commercial solution. Capable of being installed in both single and multiple configurations, the rapid growth of this type of boiler can be attributed to flueing flexibility (making siting significantly easier) the ability to modulate down to about 15% of load (matching output to system requirements) and, importantly, the achievement of over 90% fuel efficiency levels. However, condensing boilers are not the only option available to help increase building efficiency. High-efficiency boilers — sometimes also referred to as semi-condensing or modular — also have much to recommend them. Their performance is enhanced by an extensive use of copper or aluminium, with a high heat transfer rate, in heat-exchanger components and the linking of independent modules within a combined casing. Modular system
With a modular system, when heat is required the lowest module in a bank of up to 12 fires, followed sequentially by the others until output matches load. This means that energy can be conserved, as the modules at the bottom that start-up first will continually heat the non-firing upper modules, which can then act as secondary heat sinks. It also ensures that only the modules necessary to meet the system requirements are used, minimising wastage and ultimately increase operating efficiency. In the end the choice is clear. Commercial buildings can stay with old, potentially unreliable systems and continue to pay over the odds to heat buildings. Alternatively, you can take action now and invest in a new more efficient plant — and reap the longer-term benefits. Graham Williamson is business director for commercial heating with Ideal Boilers Ltd, PO Box 103, National Avenue, Hull HU5 4JN.