British Gas are really struggling in this pandemic. It’s going to take 8 weeks before they can fix our boiler, which loses pressure rapidly and whose pressure fluctuates a lot during the on/off cycle.
Not wishing to spend money and carbon using an electric heater, we are modifying our behaviour. It’s likely the fluctuations are caused by a lack of air in a container somewhere in the boiler that would normally be air-filled to damp out pressure fluctuations. And as far as we can see the loss of water is not a leak somewhere else in the system. So we only have the heating on when I’m around to check the pressure every hour or so, and I’ve reduced the water temperature (we don’t need it high) to decrease the fluctuations. (Downwards when the burner comes on and there’s cold water in a hot casing, then back upwards and beyond when the hot water spreads to the cold radiators… I guess).