Friendly reminder: if you do not have a carbon monoxide monitor in your house, go buy one. We've had problems with our boiler making a loud banging sound when it kicks in. Several plumbers have looked at it, nobody has yet fixed it. But one of them told us to buy a CO alarm, so we did. That alarm just went off while Swatra was showering. Turns out all those bangs dislodged a pipe, apparently allowing CO to escape. I shudder to think what would have happened without the alarm.