The use of water heating / solar packages can help meet the requirements of Part L as well as satisfying the customer's desire to be 'green'. Jon Cockburn explains.
Solar thermal water heating is now an established renewable technology, but some contractors still shy away from it, believing that it involves a whole new skill set. In fact, the only skill that will likely fall outside the expertise of most is working at height in order to place the panels on the roof and this is easily remedied through training.


However, there are a number of key considerations to take into account before installing a solar system. The first is ensuring the equipment is appropriate for the size of the property, its location and its anticipated hot water use. Most manufacturers can offer advice on this that includes guidelines on system sizing.
Another factor requiring careful attention is the siting and positioning of the panels. To guarantee maximum energy retention, the panel must face the sun correctly to avoid loss of heat. Ideally, they need to be south facing at an inclined angle of 30 to 50 degrees to the horizontal.

Having the right water heating equipment is also vitally important. With solar gain able to provide up to 60 per cent of domestic hot water requirements, the remaining 40 per cent needs to be generated by another method so an efficient water heater is crucial.

Solar gain will heat water in a cylinder where, if necessary, it will be brought up to the required temperature for domestic use by an auxiliary heat source such as a direct electric immersion heater or a gas boiler via an indirect coil in the cylinder. That means that selecting the right water heater is as important to the whole arrangement as the solar panels.

When it comes to the equipment itself, many manufacturers package all of the components within a single ready-to-use unit. Typically, solar packages are a 'one box' electric heating solution comprising a central heating boiler, an unvented cylinder with a solar coil for maximum heat input and efficiency, solar hydraulic and electric controls, an LCD display panel and expansion vessels. Multi-functional and easy-to-use control panels make systems simple to configure and primary solar system fluid is also included with all the necessary connecting pipe work to link the cylinder to solar collectors.

When working with unvented cylinders, the quality of the cylinder itself is critical.
Heat loss levels are key to providing efficient operation. For example, our own Megaflo eco loses almost 30 per cent less heat than the previous model. This has been achieved by using thermal imagery testing techniques to ensure all potential heat radiating areas of the cylinder are covered.

Flow rates at low pressure are also crucial, particularly in larger conurbations where pressure can fluctuate considerably. Megaflo eco, for example, features a three-piece inlet water valve control, which gives installers the flexibility to site the pressure-reducing valve at the mains water entry point and ensures balanced pressure throughout all hot and cold outlets in a property.