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Winning in the hot water generation game

The objectives of new water heating regulations are clear. The use of non-condensing water heating equipment is expected to be eliminated from 2015, says Jeff House
The energy performance of buildings is greatly influenced by the efficiency of the energy using products that serve its purposes and functions, with water heating representing a considerable energy demand. New regulatory measures defining performance standards, originating from EU eco-design Directives, are not expected to be fully in place until 2015, but their long-term objectives are quite clear. In particular, the use of non-condensing water heating equipment is expected to be eliminated from 2015, when only equipment using the more energy efficient condensing technology will be sanctioned.

This affects all products 'placed on the market' therefore it will apply to both new build and replacement installations. There will be a degree of overlap between the implementation of these Directives and existing measures such as Approved Document L of the Building Regulations, which will require clarity in future. In the meantime Building Regulations are undergoing changes which will come into effect this year.

Regulating condensing kit
The next update to the Building Regulations Part L2, due to take effect from October 2013, will enforce the application of condensing technology in non-domestic buildings, but only in the case of new build. It will not be until 2015 that the UK will be required to regulate the use of condensing technology in all non-domestic replacement applications.

Until that applies, it will be perfectly in order to replace like with like and install replacement non-condensing equipment. In such cases, it will not be until the next subsequent replacement, after the EU Directives have come into effect in 2015, that the mandatory use of condensing equipment will apply.

Reducing harmful emissions by making the more efficient use of energy mandatory should lead to a welcome reduction in energy bills, which will be an important factor when the overall cost of replacement is assessed.

However, the high cost of producing environmentally friendly energy for grid distribution is likely to mean that switching to condensing technology will lessen the impact of increasing energy bills rather than reducing them. The significance of this concealed, hard to quantify benefit may not be apparent if the question of the replacement of a non-condensing water heating system arises when it is still possible to replace it on a like for like basis.

However, experience shows that the cost of the energy needed to operate a non-condensing water heating system until it must be replaced compulsorily by a more energy efficient condensing system, will noticeably exceed the energy cost of making that transition at the outset. But financial matters are not the only considerations to factor in when a new installation or replacement project involving condensing equipment is being evaluated.

A simple, plug and play swap between the old non-condensing and the new condensing heaters involved should not be expected, as the technologies operate in different ways. For example, in general terms, in a non-condensing water heater, gases generated in the combustion process pass through a heat exchanger and are then released, still at a high temperature. In a condensing water heater, the otherwise wasted heat is extracted from exhaust gases by means of a larger or additional heat exchanger, the gases being released at a much lower temperature. The cooling process causes water vapour formed during combustion to collect as condensate, which must be suitably drained and the flue system employed must be of suitable construction to accommodate 'wet' flue gases. These same technical considerations will apply equally to hot water production via a calorifier or plate heat exchanger, as the boiler supplying the heat will also need to be of condensing design.

The application of condensing technology to a commercial water heating system may provide the opportunity to consider a complete re-design, enabling the introduction of a prefabricated solution. Bespoke design, off site construction, simplified delivery and greatly reduced change over down time are all benefits associated with pre-fabricated solutions. When coupled with whole life cost efficiencies these represent an attractive option.

LZC technologies incorporated
The prefabricated solution could incorporate both low to zero carbon (LZC) and condensing technologies, maximising the energy efficiency potential. Certain technologies can also enable an application to be made for tariff payments under the RHI (Renewable Heat Incentive) scheme. Recent statistics show that 90 per cent of accredited installations in the non-domestic sector use solid biomass fuel, typically in the form of wood pellets or wood chips. Biomass technology in particular lends itself to a pre-fabricated approach as fuel storage, fuel delivery systems and buffer vessels can be incorporated into a single, containerised plant room.

Depending on the characteristics of the location, a packaged solution can be installed in an existing plant room or supplied in an outside, purpose-built enclosure.

Leading manufacturers can be relied upon to provide information regarding all of the complexities associated with making these important decisions and to offer appropriate solutions. A full portfolio of products across all output ranges and demand profiles, including prefabricated options, will give the widest possible choice and ensure full compliance with all standards and statutory requirements.

// The author is marketing and applications manager for Baxi Commercial Division //
17 April 2013


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