My Lasko 5000L won't work.

SOURCE: No Water flow thru Humidifier

Loosen the brass fitting where it connects to the soleniod valve. If water comes out your saddle valve is ok. Carefully retighten this fitting. With the humidifier turned on loosen the first fitting down stream from the valve see if water comes out. if it does turn the humidifier off and see if it stops, it should. That will tell you the the valve is ok then, just clean the filter and the oriface. if it does not turn on and off check the wiring. if ok replace the valve.
Good luck

SOURCE: The humidstat light is on when I first try to get

This is normal, based on where you have the humidistat knob set to, it will go out only after reaching the humidity level set on the knob. Also if you have it setting in a fairly large open area of your home, it may take a loooong time to reach the proper humidity level. My cousin has one of these units setting in his living room, which has a cathedral ceiling, the unit's humidistat light never goes off, and the unit runs continually, unless the resevoir runs low. But the unit operates fine.

Hope this answers your question. You may refer to your user's manual regarding this, or if you don't have a copy, you may download one at this link: http://ec1.images-amazon.com/media/i3d/01/A/man-migrate/MANUAL000006709.pdf

kcomp1863

SOURCE: I have a aprilaire model

I installed a new unit, and the fan and solenoid would not operate. I checked that the board H leads closed during test, all the wiring continuity, and the solenoid by applying 24vac to open and close it. Because components checked, and wiring checked, I finally looked at the connections to the fan, at the current sensing relay switch. The human error was a loose spade connection from factory assembly! Once all those connections were tight, the unit is functioning properly.