The payback period is all too often ignored when assessing the most energy-efficient ways of generating hot water, according to Tony Billett, chairman of Zenex Technologies
With current gas and electricity price increases, saving energy in the home has never been more important.

Plumbing and heating installers have a golden opportunity to help householders by offering solutions that can reduce their utility costs.

One of the biggest areas for potential savings is through generating hot water in the most energy-efficient way possible.

As water plays such a crucial role in our everyday lives, there is plenty of scope to help consumers save energy, domestic hot water (DHW), and consequently save money.

Installers do not have a shortage of options when it comes to finding ways of generating hot water. Solutions are as diverse as solar water heating systems, heat pumps and other boiler adaptations which recover waste energy.

Perhaps the simplest method to calculate the savings these offer is to look at the payback period of each solution.

With solar, analysis nearly always overlooks the high initial outlay costs. Despite some government grants being available, the payback period for a solar water heating system can be more than 100 years. There are few incentives for even the youngest home owner to install a solar hot water system if they want to reap the benefits in their lifetime.



While the Centre for Renewable Energy does not endorse any particular products, it does issue some very useful information for consumers on request.

Installing a solar water heating system, the independent organisation says, will typically cost between £3,000 and £4,500. It reports that there will typically be savings of around £50 each year. Based on a gas-heated three-bedroom semi-detached house, the payback period would be between 60 and 90 years.

Taking the information from another independent organisation's website, the Energy Saving Trust, utility customers get payback periods for the same water heating system of between 80 and 112 years. The calculations are based on the supplied figures of between £3,200 and £4,500 for initial set-up and annual savings of £40.

Future prices

Of course, both organisations do stress, though, that the actual savings will depend on future utility prices. But, with all major suppliers putting up their tariffs in the past 12 months, it is only likely they will be increased further in coming years.

The good news, though, is that, if you look at the issue of hot water generation more closely, cheaper and more efficient ways of saving money on energy bills become apparent. For example, independent tests have proved that efficiencies can be made from recovering waste heat from the flue of modern condensing boilers by installing a passive flue gas heat recovery device. Evidence of the availability of this energy can be seen by the stream of hot, moist exhaust often visible at the flue exit of the modern boiler.

Cutting consumption

The GasSaver, for example, is simply installed on top of a boiler and reduces gas consumption required for domestic hot water by up to 50%. It also cuts water consumption by reducing lukewarm waste. With this device, incoming cold mains water passes through one heat exchanger in a thermal store and another in the flue.

Water, on leaving the store is heated to a temperature as high as 80°C and is then blended with the cold mains water to 30°C for entry to the boiler. With a cost of less than £600, the GasSaver has a payback period of just three to five years, which represents significant overall cost savings for householders.

Visit www.zenexenergy.com