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Future remains bright for condensing boilers

We have all heard the expression “nothing is forever”, but majority opinion in the HVAC industry is that condensing boilers have a long and productive future ahead of them.

While everyone expects the role of renewables to grow, the dominance and potential of boilers are two factors highlighted by those who believe the UK will continue to be a large consumer of this technology for some time to come.

The first of the industry experts consulted by H&V News highlights how the changes to Part L of the Building Regulations have affected installers. Ariston product manager Gareth Ash, says manufacturers are offering products and services to ensure installers are fully supported and able to meet the new requirements.

Efficient products

Part L of the Building Regulations refers to “conservation of fuel and power”, says Mr Ash, so these changes deal with energy efficiency at the level of energy-using products, appliances and systems, as well as the integration of renewable technologies.

Now, all boilers installed in the UK must be SEDBUK Band A rated (under SEDBUK 2005). The SEDBUK efficiency rating system is currently being reviewed, but under new proposals - which take into account hot water efficiency - a minimum efficiency rating of 88 per cent will be required.

Consequently, it is now illegal to install any boiler that is rated 87 per cent or below.

Installing a Band A boiler is similar to installing a regular Band B appliance. The main difference occurs during the commissioning of the boiler, says Mr Ash. Band B appliances incorporate a standard burner which means that, during the combustion set up, the installer simply needs to check the gas pressure using a manometer, adjust the gas valve until the gas pressure is correct and the installation is complete.

However, Band A boilers have only one heat exchanger and a pre-mix burner. Instead of a man­ometer, the installer must use a flue gas analyser to commission the boiler safely and accurately. This ensures the gas combustion is working correctly so the boiler is safe and efficient.

The flue gas analyser consists of a small box with a pump and a digital display. It shows the installer what the CO and CO2 levels are in the boiler’s waste gas and calculates the ratio between the two. If the combustion levels are wrong, the installer will need to adjust the gas valve, see it stabilise and adjust again until the levels are correct.

Simply by acquiring a flue gas analyser and becoming competent in its use through a short training course, as offered by leading manufacturers, installers can quickly and easily switch to installing Band A appliances.

The other big change to boiler requirements in the new Part L legislation refers to zoning. Where the entire central heating system is being replaced, in properties up to 150 sq m the system must be divided into two space heating zones, usually upstairs and downstairs, with independent temperature control.

For properties larger than 150 sq m, the same rule will apply but zones must also be independently timed. Some modern Band A boilers offer advanced integral temperature control systems that not only carefully monitor and regulate the boiler’s output to suit the exact requirements of the household at any given time, but are designed ready to accurately control two separate zones simply with the addition of a two-zone switching valve.

These advanced models are actually as straightforward to install as many other Band A boilers and do not require complicated wiring arrangements. In order to optimise temperature control and minimise boiler output still further, external controls such as outdoor sensors can also be integrated for further accuracy and efficiency.

The retrofitting market

The growing urgency to reduce carbon emissions and energy consumption means the focus of our industry’s efforts will increasingly be on retrofitting existing buildings, says Vaillant UK and Ireland commercial director Dave Lacey. This creates both an opportunity and a necessity to marry existing ‘traditional’ heating technologies with renewables.

Mr Lacey believes it is vital that design engineers focus on creating solutions that can be applied without disrupting the operation of occupied buildings. They must include the necessary controls and integration strategies to extract the maximum benefit from all the technologies available to building contractors.

Traditional market

While renewables will take a greater share, the evolving refurbishment market will remain dependent on traditional heating technologies, including high efficiency gas boilers, for some time to come and their importance should not be overlooked. Indeed, most design professionals will tell you high efficiency condensing boilers will have an even more important role to play when the commercial new build and refurbishment markets fully recover, Mr Lacey says.

Commercial boilers still have a key role in cutting carbon emissions. While renewables and micro­generation will take an increasingly large share of the market in the coming years, boilers will still be relied on to provide the lion’s share of commercial heating.

This will be particularly apparent in areas where the market is strong, such as in schools and retail properties.

It is also imperative that we continue to make our commercial boilers as efficient as possible and, when they are working in tandem with renewables, to get the configuration and controls strategy spot on.

Condensing boilers will only achieve their maximum efficiency in situ if the flow and return temperatures are closely controlled. This is why weather compensation control is being included in more of today’s designs, in order to keep systems in condensing mode for longer without compromising on comfort.

Low-carbon compliance

People need heating and hot ­water at a reasonable cost, especially at a time of rising fuel prices and increasing fuel poverty, says Baxi Group UK marketing director Sarah Brook. A new boiler is usually a distress purchase when the boiler breaks down and people don’t usually expect to spend upwards of £10,000 on an entirely new heating system.

It will take a long time to change the nation’s mindset regarding low carbon technologies. Our current central heating systems fit in with our lifestyle and are designed to suit our homes. Legislation and carbon reduction targets will drive the newbuild and public sector markets to install low carbon technologies.

However, replacing old boilers in the existing housing stock is where the future of the boiler market really lies, probably with the addition of low carbon technologies.

Upgrading to a SEDBUK 2005 >90 per cent boiler can save the householder around £235 a year on gas bills (according to the Energy Saving Trust), and the environmental benefits from substantially reduced carbon emissions. According to HHIC, there are still more than four million Band G boilers in use in the UK, each working at less than 70 per cent efficiency.

To bring those heating systems up to current standards, the government should be encouraged to introduce another boiler scrappage scheme, or a special tax rate, says Ms Brook.

The UK has one of the best gas networks in the world and a skill base of more than 126,000 Gas Safe registered installers. Introducing biomethane would green the existing gas grid and help to supplement the reserves of natural gas. Biomethane can be produced from landfill gas and animal manure, providing an almost endless supply.

No panacea

Baxi does not believe there is a single silver bullet when it comes to new low carbon technologies. It is important that the most appropriate product for each installation is specified and installers should be properly trained so that they can advise, specify and install the right technologies.

Micro-CHP is the logical successor to the condensing boiler. It looks and acts like a conventional boiler, making it a more familiar replacement for the householder. In addition, it generates electricity, saving money and providing a ­financial incentive through the feed-in tariff.

Gas boilers will continue to be centrally developed and modified, made more efficient, generating electricity as well as heat, and it will take a long time for them to disappear altogether.