Which uk24 Oct 2012 21:15
2. VPhase voltage optimisation device - £300 (plus installation)
The VPhase is another voltage optimisation device and claims to cut around 10% off your annual electricity bill by dropping the voltage in your home to 220V. It needs to be installed by a qualified electrician.
Why it's not worth it: It did better in our test than the Energy Wizard (see above), and saved some power when we turned on lights and used a vacuum cleaner. The instructions say that it will not save any energy when connected to closed loop (thermostatically controlled) heating. We tested it with a plug-in electric convection heater (with a thermostatic control) and found that it actually increased energy use – the lower output meant that it had to be on for longer. It’s pricey and will take a long time to pay for itself.