Anyone know why my gas fired back boiler kicks into life every now and again even though I've got the central heating and hot water switched off at the immersion switch? The back boiler is located behind a gas fire in the living room. I nipped outside and observed the gas meter spinning round merrily so it's definitely using my gas supply. I did wonder if I was somehow sharing a boiler with next door as our fireplaces are back-to-back although I find that unlikely?? Anyhow, I was just trying to fathom out why I'm paying for gas when everything is switched off. There are no other gas appliances in the house. Can be doing without a gas bill like the last one!! Cheers.