When water starts pouring out the top of a window, something is very wrong.
Luckily, we were around for the incident and I suspected the cause immediately. The hot water baseboard heaters I put in the bedroom upstairs. I thought perhaps the valve had leaked but actually a 1 inch tear had opened up in the middle of one of the units. I know the piping is thin in those but there’s no way it should have burst under regular pressures–especially since it is on the second floor and so receiving relatively low pressure anyway.
Good thing we have that bedroom and the adjoining bathroom on a separate loop so we can shut it off and keep the rest of the system operating. Hopefully, I can cut out the broken part and solder in a repair. That won’t be easy, though, since the pipe is designed to dissipate heat.