Is there an alternative to a self-piercing saddle valve for a humidifier?
I had a self piercing saddle valve on my whole house humidifier when I bought the house.  It had developed mineral deposits in the piercing hole and no longer worked.  I ended up taking it off, cutting the pipe and sweating in a regular valve.  Self-piercing valves are notorious for clogging up and also for eventually leaking.  Since it is in you attic, any leak would drip down onto you ceiling and cause water damage.  I would consider replacing it with a regular valve.