There are a number of issues to be considered when installing hot water, heating and storage products, not only in terms of improving performance but also reducing energy use and carbon emissions.
The method of water heating used within a property will depend upon whether it is located in a gas or off-gas area. While the majority of UK households do have access to mains gas, there are still an estimated four million households (15% of the country’s population) off the grid – and therefore limited to a choice of oil, LPG, solid fuel or electric.
A typical off-gas family faces fuel bills up to 120% higher than a mains gas user (and some 32% are classed as being in fuel poverty). So, it’s important for installers to fit cost effective systems where possible. Fortunately, electric water heating offers high levels of controllability and reliability. Floor-standing, direct unvented cylinders are one such product that can be installed, as these heat the water via an electric immersion in direct contact with the water; this, in turn, reduces energy losses that can be experienced from pipework, as well as circulating pumps. However, to ensure optimum efficiency, it’s important that they are sized correctly. Generally, a 150-litre capacity water heater or hot water cylinder is sufficient to satisfy the requirements of a three bedroom house.
A technology already common throughout Europe is the heat pump water heater, with 70,000 pieces being fitted in 2012 alone. These types of products, such as Ariston’s NUOS, are now growing in popularity in the UK. Heat pump water heaters combine a cylinder with a heat pump, which uses an external duct to capture the heat from the ambient air. Combined systems of this type provide an excellent Coefficient of Performance and can deliver energy savings of up to 75% when compared to regular electric hot water storage cylinders.
For areas of the UK where gas is available, the method of hot water supply is, more often than not, predetermined by the choice of central heating system. Furthermore, hot water requirements tend to vary, depending on usage – as opposed to less relevant factors such as boiler location, cost and ease of installation. The issue is clouded even more by the numerous water heating systems on the market, although there are really only two main types of system: instantaneous water heating (which heats water as required) and hot water storage (which stores hot water ready for use).
The humble gas boiler continues to be installers’ favoured method of water heating. Indeed, the Energy Saving Trust (EST) reports that boilers used to heat homes and hot water account for 55% of what is spent on annual energy bills – so an efficient model can make a big difference.
Installers should be well aware by now that fuel bills can be reduced significantly if a homeowner’s boiler is replaced with a modern, high efficiency, SEDBUK ‘A’ rated model. Should end users have recently had a new boiler installed, they may also be interested in integrating external advanced boiler controls.
While the gas boiler remains a stalwart of water heating, people are more frequently asking about renewables, especially solar, so installers will find it useful if they are able to recommend a compatible cylinder. Many solar thermal panels can be used with an existing water system or as part of a new installation in combination with an indirect or twin coil cylinder.
Following recent changes to Part L, cylinders are now more highly insulated to reduce heat loss; in fact, those offered by Ariston have achieved EST Recommended status. The regulations specify that provisions should be made for the conservation of fuel and power, so that greater efficiencies can be achieved.
However, if an end user’s primary heat source is electric, there will be no boiler to serve the top coil. In cases like these, a single coil cylinder should be used, which sees an electric immersion heater used as the primary means of heating the water, while the single coil is connected to the solar thermal system as a secondary heat source.
Given that there are so many different water heating options available, it’s important that installers fully understand the technologies that are out there and are trained accordingly. This will enable them to fit the right products for the right applications, while providing their customers with value for money.