Heating and Ventilating


Maximise benefits through a holistic approach

With fuel costs on the rise, it is becoming increasingly important for commercial and industrial applications to help investors to mitigate this increase. Pete Mills, explains how taking a more holistic approach to the provision of heating and hot water can result in bespoke systems which maximise efficiency levels
ONE OF THE most openly debated topics in the commercial and industrial industry is the impact of fuel costs, which are undoubtedly on the rise and stretching budgets to extremes. In light of this, we are regularly seeing instances whereby stakeholders are actively seeking alternative solutions which not only meet their energy requirements, but help to reduce costs.

When it comes to the provision of heating and hot water in commercial and industrial facilities, it is often found a combination of technologies is the best way to achieve significant savings on fuel. A well thought-out system can increase the likelihood of a favourable return on investment, which will in turn lead to quicker payback on the initial financial outlay.

For those thinking of embarking on a boiler replacement project, the good news is that carrying out work to upgrade a system needn't be as intrusive as you might expect. Whilst one solution definitely doesn't fit all, there are ways and means of integrating new condensing boilers into existing systems and pipework, without the risk of any contamination of the new boiler from the old heating system and loss of performance.

Today, most high performance condensing boilers need to be installed as part of a sealed system, and those that don't still benefit greatly from being separated from an ageing system where the water quality may be difficult to control. For certain applications, conversion from an open vented to a sealed system can be tough to achieve with potential leaks from old pipework and fittings to consider, as well as the possibility of corrosion problems if the water from an ageing system is allowed to circulate freely around a brand new condensing boiler.

In situations like these, the most practical way of overcoming this kind of problem is to leave the existing system open vented whilst separating the boiler primary circuit using a stainless steel plate heat exchanger. Introducing a plate heat exchanger to the system ensures a safe and protected primary circuit for the new condensing boiler, whilst also ensuring there is no risk of system leaks from a higher sealed system pressure and eliminating any corrosion or restriction issues.

Renewable specification
As with any installation, the key to ensuring the most ideal technologies are selected is having a detailed understanding of the end-user's requirements from the outset, which means a thorough specification process is required.

The emphasis when selecting the technology should be less on selecting a technology and more so on coming up with a winning combination that delivers the maximum benefit for the end user. There are a number of renewable technologies available on the market today, ranging from solar thermal panels to gas absorption heat pumps, and each has different strengths and limitations.

The perfect example to illustrate how one technology can fit the needs of an end user with particular requirements is solar thermal panels. The technology incorporated within the panels is ideal for applications where there is a high demand for hot water. By trapping solar radiation between a layer of glass, a micro green-house effect is created which then allows solar fluid to be passed through the hot absorber to soak up the free energy. This, in turn, can then be stored ready for use in a solar storage cylinder.

Whilst this technology offers a short payback period in its own right, by combining with an existing boiler, the end user can benefit from a system which offers up to 60 per cent of the annual hot water demand for free, with the boiler capable of meeting the extra demand when this is particularly high.

System alliance
One such arrangement for applications with sufficient demand for both electricity and heat is the incorporation of a combined heat and power (CHP) module. As heat is produced as a by-product of the power generated and by distributing via a thermal store, the technology lends itself to operation alongside any other heating source - a high-efficiency boiler being one of the most common examples.

The key to a successful systems alliance comprising CHP is that the system is designed to utilise 100 per cent of the heat generated. With premium efficiency levels and cost savings, the ultimate objective for such an arrangement, it is vital that no heat is rejected, which would have the potential to jeopardise the system's effectiveness and compromise the cost saving benefit. To avoid the dumping or wastage of heat, it is essential that the CHP module is correctly sized. Failure to do so from the outset of a project is likely to result in the production of too much heat for a building, which will nullify any potential performance enhancements. In most cases, CHP units are installed in tandem with boilers, however it is also possible to utilise the benefits of an alternative appliance. Whatever the arrangement, the key to reaping the benefits of a CHP system is to ensure it is sized to the thermal base load of a project, or 20 per cent of the peak load, to allow for maximum efficiency. Whilst CHP will meet a building's base heating load requirements most of the time, a secondary source will be required in most cases, to satisfy a building's peak heating load.

Although there are a number of technologies available in the marketplace which can achieve results in isolation, taking a step back and looking at the system as a whole offers the potential for huge benefits to be reaped. A well thought out system design can not only ensure the arrangement best meets the requirements of the application, but also helps to minimise expenditure.'


// The author is the commercial technical operations manager at Bosch Commercial and Industrial Heating //
22 January 2014


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