Even when your heating’s switched off, a very efficient HIU still requires a small amount of energy to run, to make sure you always have heating and hot water on demand. This means there’ll be a very minimal amount of energy being used to keep the HIU working as it should.
So that we can cover our costs to keep the heat network running, the daily standing charge applies at all times, regardless of whether you’re using any hot water, or if you have your heating on. You can find out more about what your daily standing charge covers here https://www.watkinsenergy.co.uk/charges.html.