anything if you’re trying to fix it & don’t know how,,, most boilers now have auto-fill but there’re many still working fine that don’t,,, 1 valve for fill & another for drain.
btw, boilers are never filled to capacity,,, suggest you call your hvac guy & have him stop by for a look-see – BE THERE when he is,,, you could be jeopardizing your family’s safety poking where you’re not familiar.
http://www.itsreallyconcrete.com
decorative concrete artisan
concrete repairs