The rise of combi boilers has focused industry attention on the features and benefits of this very popular product category. There are instances however, where even this most adaptable of products is not suitable for certain types of requirements and only a hot water storage system can provide the solution. Martyn Bridges, Director of Marketing and Technical Support at Worcester, Bosch Group offers a reminder of the importance of cylinders and the role they play.
“The industry’s move towards combi boilers, and ever increasing sales in this area, has seen the merits of mains pressure systems coupled with hot water storage cylinders forced out of the limelight to some extent.
“However, demand for cylinders is still strong in our industry, particularly in larger properties or buildings where plans are in place for solar systems to be fitted. As a result, there is still plenty of business to be had for installers keeping a close eye on the market.
“At present, there are currently 23 million homes in the UK with central heating. Estimates also reveal that there are around 16 million combi boilers fitted in these homes. This suggests that around 8 million properties in the UK are without combi boilers and in these situations the majority will have hot water cylinders installed in airing cupboards (or other locations). This still represents a very sizeable market, especially where replacement opportunities are concerned.
“The variety of products available on the market has also increased over the years and cylinder designs have improved too. Today’s modern hot water cylinders are very different to those produced years ago. Going back 10 years or so it wasn’t unusual to find cylinders installed in peoples properties made from raw copper with no insulation or just an insulation jacket tied around them to prevent heat loss. In contrast, cylinders are now leaving the Worcester factory with insulation included within the product composition and a casing structure developed specifically to help maximise heat retention.
“Our latest product offering has been designed to comply with the ErP directive, which dictates a maximum heat loss of around no more than 2kw of heat per day, ensuring the household fully benefits from the reduction in heat loss and saving in energy. It is good news that technology is to offer such improved performance but in reality it will take some time to upgrade all UK homes to levels compliant with the ErP directive. New cylinders will be installed as and when old ones need replacing.
“Taking a typical example of a semi detached property with a 150 litre cylinder, in SAP this equates to a daily energy requirement (at the outlet of the system) of 1846kWh per year(5.06 per day which is close to the ErP medium profile). If we use SAP entering zero insulation thickness then we get a water heating consumption (to the boiler) of 9205 kWh per year, 25kWh per day which isn’t really realistic. Whereas if we enter a thickness of 12mm then we get 5161kWh per year and if we enter 50mm we get 4213 kWh per year. As you can see SAP has been designed to deliberately encourage direct input of heat loss rather than insulation thicknesses therefore it is very difficult to estimate the real heat loss from older cylinders.
A reasonable estimate for a 10 year old cylinder designed to BS 1566 heat loss test of the time would be around 7Kwh per day of heat loss and if this is entered into SAP as a declared value we get 5588kWh per year. On this basis we could see savings of at least 3.8kWh per day or 1407Kwh per year, this is a significant amount of money, especially when you consider the Government’s nationwide focus on encouraging homeowners to reduce the amount of energy and money. Whilst there is much discussion about cavity wall insulation, double glazing and SEDBUK ratings, the energy efficiency of hot water cylinders is seldom talked about, perhaps due to the fact they are hidden from view in most households.
“The poor insulation of old cylinders isn’t the only area of concern. The amount of heat used to heat older cylinder is also questionable. For example, the heat exchangers fitted in modern cylinders can heat water in rapid time whereas older units often have exchangers that take significantly longer to heat a cylinder of water.
“Whilst the government has invested lots of time and money in the promotion of all types of property insulation, we appear to have overlooked the role of the cylinder and the importance of updating these units as well. And, whilst a lot of homes in the UK will now have a high efficiency condensing boiler, too many of these may be fitted in conjunction with a non-efficient hot water storage cylinder. I would therefore suggest that it is time we turn our attention to this area of the heating sector and focus on the efficiency of complete systems, rather than the individual components.
“To do this effectively, it would be a good idea to set up some sort of cylinder scrappage scheme, which aims to reduce the number of older hot water cylinders fitted within homes. This would ensure more households have modern cylinders fitted alongside high-efficiency condensing boilers, thus reducing the amount of heat coming out of the airing cupboard and ultimately into the atmosphere.
“Whilst it may take some time to implement a scheme of this type, installers could take the initiative to actively check cylinders and advise homeowners on the benefits of regular servicing in the interim. If we can bring hot water storage to the forefront we can ensure cylinders won’t be sat in the airing cupboard for the next 20-30 years operating at inadequate levels during this time.”
For more information on Worcester, Bosch Group and its Greenstore series of unvented hot water storage cylinders, visit www.worcester-bosch.co.uk.
[author image=”https://www.installeronline.co.uk/wp-content/uploads/2013/01/martynbridges.jpg” ]Martyn Bridges began his career as a heating and plumbing apprentice and has grown up with a strong knowledge of the technical side of boilers. He joined Worcester, Bosch Group in 1986 as a Technical Service Engineer and worked his way through the ranks to become Director of Marketing and Technical Support in December 2004.[/author]
