Sorry Dave, I wasn't making conspiracy theories



I think it's stating the heat losses through the insulation as an electricity consumption figure as well but it's a bold figure to state without any qualification. There's a few things that should also be stated such as the difference between surrounding ambient air temperature and the temp of the water in the cylinder during the test. Also does this loss refer to a cylinder with insulated or lagged inlet and outlet pipework or one without pipework lagging. Finally does this refer to a cylinder under normal day to day use which would have temperature variations or one that's sitting static under fairly constant temperature (although I'm not sure how you'd measure the losses accurately when it's being used) .

It would be interesting to slap a data logger on an unused cylinder for a day and see how close this figure is under real life conditions. It sounds very optimistic to me.