Much has been written in the trade press over the past few months about forthcoming legislation that will affect M&E system designers, installers and suppliers of heating equipment.Legislation is surely going to come and,when it does,it will affect us all in the way we specify,select and operate our plant,however it is becoming clear that the Climate Change Levy,revisions to Part L2 of the Building Regulations and the introduction of the Energy Performance for Buildings Directive will have the greatest impact.
Energy saving
With regard to combustion equipment,what we know of impending legislation is primarily concerned with boilers. However,it is confidently predicted that water heaters will follow in the legislative agenda as they have a significant impact on the energy performance of buildings.Indeed,in many cases,water heaters can be the major energy user as in sports facilities and hotels with seasonal demand for hot water.Already independent gas-fired water heaters are recognised as contributing to considerable energy savings in many applications by the separation of hot water from the space heating load.
This arrangement has largely superseded the old boiler/calorifier system,whereby the boiler has to be fired up all year round even in the summer for production of domestic hot water,which is uneconomic. Now the independent water heater performs its own dedicated function all year round so the boiler can be shut down during summer months. Independent water heaters have also shown savings that are due to their small footprint and,as this allows them to be installed close to the point of use;further savings can be gained through reduced transmission losses.
Condensing technology
Therefore it is logical that these versatile independent gas water heaters should take the next step by becoming intrinsically energy efficient.To that end condensing technology has been developed and applied to independent gas-fired water heaters and is now available. It is therefore possible to match the performance of condensing boilers with their equivalent condensing water heaters whether they are of the storage or non-storage type,in the plant room or at the point of use.
That Government has at long last taken notice of these advances in the industry and its acceptance that gas-fired water heaters do play a part in energy saving is confirmed by inclusion in the Energy Technology List,albeit under the heading of boilers with the sub- heading of condensing water heaters.This is the list of energy approved equipment on which it is possible for companies to receive tax breaks under the provisions of the Enhanced Capital Allowance Scheme set up to help offset the punitive impact of the Climate Change Levy which was introduced in April 2001.
As mentioned earlier, gas water heaters can be of the storage or non-storage variety.With their small footprint,condensing storage water heaters will give the same versatility in application as their standard-energy counterparts that are widely used in the UK today.
Storage condensing water heaters
Condensing storage water heaters can be sized to meet the demand of any given building,independent of whatever the space heating load might be.Obviously the demand for water heating and space heating can vary widely, both in the daily pattern and seasonal pattern. Generally these appliances are self-contained with their own burner and flue.Achieving around 106 percent nett efficiency,these high performance units are produced in a variety of configurations some have their combustion external to the water storage area and some have the combustion and heat transfer within the storage tank.Both glass lined and stainless steel products are available and therefore can take account of water quality in various parts of the country. Perhaps the most interesting development with these condensing water heaters is the fact that they are available not only with remote control capability but also with computer diagnostics.This feature brings them in line with the more superior high efficiency boilers that are available on the market.
Non-storage condensing water heaters
High volume non-storage condensing water heaters have been around much longer than their storage counterparts.They are either copper or stainless finned tube heat exchangers and have generally had higher performances and a larger range of capacities than storage units.They are usually lightweight and can therefore be installed in unusual situations such as mezzanine floors and,compared with a boiler/calorifier system,can save on space with their smaller footprint.Depending on their application,non-storage units can have additional direct storage tanks added to the system,particularly useful where there is intermittent high demand for hot water.
Improving energy performance
The Building Energy Efficiency Directive will impact greatly upon the operating and running costs of most commercial buildings, targeting particularly those with floor areas in excess of 1000m2.
The objective is to improve the energy performance of buildings using new standards for calculated and, more importantly,measured energy performance validated by a ten year certificate,subject to regular inspections.The use of indirect gas-fired water heating, especially the newer condensing technologies,can contribute towards attaining better energy performance ratings for these buildings.
