Product review (3 stars): Fine tuning..
I have one of these valves on my humidifier, it was not opening when energized.. After tinkering with it I found that the packing was to tight.. So if yours isn't letting water thru try this... Remove the solenoid from the stem, use a small screw driver and tap the packing nut counter clockwise until you can spin it with your fingers.. Hand tighten clockwise, do not use any thing but your fingers to tighten.. You should be able to spin the stem..  After this mine works fine. It won't leak.. There is a rubber o ring type seal under the stem... Doesn't take much to seal.. Reinstall the solenoid and energize.. You should hear it click.. See if you can blow thru it.. If not.. Try loosening a little more.. Good Luck!