High efficiency is not the be all and end all
March 1st 2008

Despite the heating industry's excellent response to Part L2 and L2a of the Building Regulations, which has seen the move towards high efficiency (HE) boilers really gather pace since April 2006, Graham Williamson, business director of commercial heating at Ideal Boilers, argues that standard efficiency (SE) appliances still have a major role to play in the non-domestic sector

Without doubt, the last 18 months have been extremely challenging for everyone involved in the heating industry, particularly installers and specifiers. Not only have they been charged with getting to grips with the complexities of the Building Regulations, but they also had to do this in a relatively short space of time, as the approved version of the Part L document was rushed through to meet its deadline.

The good news is that despite these hurdles, the industry as a whole has embraced energy efficiency. There is now a wide range of HE commercial condensing boilers on the market that meet and exceed legislation requirements, offering installers and specifiers more choice and options. To complement this, manufacturers and trade industry bodies have taken the initiative and produced a range supporting information to help installers understand what they actually need to do to comply.

But while there has never been a better time for installers to help their end-user customers take advantage of a high efficiency heating and hot water system, it is vitally important they recognise that a HE boiler may not be the right solution for every application.

The fact remains that a HE boiler will only condense when the system allows it to do so, crucially, when the return temperature is maintained below 50°C. However, because commercial and industrial heating systems in UK buildings can be as much as 20 to 30 years old, many cannot easily adopt condensing technology, either through design or suitability. With the replacement boiler sector accounting for approximately 70% to 80% of all commercial boilers installed, careful consideration must therefore be given to overall system design before choosing either a HE or SE boiler for a replacement project.

So what factors do installers need to take into account before making the right selection for their end-user customers? The main consideration is the flow and return temperatures that commercial buildings are designed on. To gain maximum benefits of a condensing boiler for example, the system must be designed on a 60°C flow – 40°C return. However, currently the majority of systems are designed on 82°C flow – 71°C return. If this is overlooked, the rated output of the appliance can significantly reduce by as much as 8%.

Secondly, installers must think more carefully about flue positions. It is critical that the flue system is inspected to not only ensure it is in sound condition, but also that its construction is suitable for a condensing boiler. Due to the high level of condensate that will be formed within the flue system, the material used must be impervious to the acidic nature of the flue gases to prevent a serious failure.

Controls also have a significant role to play. Whether you are installing a SE or HE appliance, unless it is managed and operated properly in an appropriate manner, the benefits of even the most energy efficient boiler will be significantly reduced.

There are other factors too that have to be taken into account. This includes looking closely at the water distribution characteristics and, because the mean water temperature is lower in a HE system, designers need to consider radiator sizes as well, in order to meet the heating requirements of a building.

If these factors are not taken into account, then a condensing boiler installed into an existing building using traditional design parameters will not gain maximum benefits.

It is for this reason that recognition was given in the Building Regulations (L2B for existing buildings) for the use of SE boilers.

In fact, by more accurately sizing a replacement boiler (through a system load assessment) and evaluating the controls, a modern SE boiler could offer the same carbon reduction benefits, that are possible had a condensing boiler been installed.

Ideal Boilers is the leading manufacturer in the commercial and industrial heating market. The company has been at the forefront in the drive towards energy efficiency by introducing a range of highly efficient appliances that meet and exceed legislation requirements. To compliment this, we also offer a comprehensive range of standard efficiency appliances, offering installers and specifiers greater flexibility, choice and options.

Overall, the key is that both standard efficiency and high efficiency boilers have their place in the market, therefore it is essential installers and specifiers consider the application of these products along with the requirements for installing them in their own right. By doing this, building service managers will benefit from the most cost-effective and energy efficient solutions for their premises.