I've been monitoring it for 14 months since I realised they only use shower when my family members do . I only turn the water off at stop tap for half an hour when I get fed up of the constant pipe bumping. if they had their own hot water it'd just switch on and they would not have to keep trying the taps ,would they. It always magically works and the pipe bumping stops when my hot water setting is on. I do remember my landlord telling me " the meter and boiler must stay on at all times " when I went to switch off the gas at meter but I put it down to him not realising it is automatic and will switch on when there's gas available or old fashioned sexism , thinking women don't understand the workings. I've had a gas engineer in who witnessed what I described but the pipe can't be followed properly because it's buried in the concrete of the cellar steps so I'm forced to turn the water pressure low and run the sink taps to stop them mooching while my family are in shower ( not enough water for both that way) and they had the cheek to come outside and shout stop messing with the water! I will not repeat my response.