Originally Posted by Wet_Boots
It is a problem on systems without proper drains, because everybody can do everything correctly, and water can leak through a faulty system shutoff valve to collect and freeze outdoors.
Thats why I always leave boiler drain open. Put a note on the invoice that if they see water coming out of BD , DO NOT SHUT IT , call us and I will replace shut off. Also provides another weeks work at season end.