I have a Honeywell Enviracaire Furnance humidifier. It started leaking a lot. When I looked inside, the filter was really badly corroded. I replaced the filter and hooked it up again. It still leaks at the bottom.

SOURCE: Water flow through humidifier

The solenoid that turns on the water to the unit should not change the water flow, so you should get the same amount of water that flows into the solenoid. If you want less water, you can partially close the valve at the water source.

SOURCE: Humidifier leaks

My Air-O-Swiss U7142 has a leak from the very bottom. I found that as long as the water flows on to the "pan" that evaporizes the water, the water will come out from the bottom. Does anybody know how to fix this?

SOURCE: cleaning a furnace humidifier steel filter?

Most water panels are generally replaced once a year on flow through humidifiers.

SOURCE: water keeps running into humidifier even furnance blower is not

This sounds like, the 550 transformer is not connected to the blower motor power connection (in parallel)

SOURCE: need to replace the hb1 valve (mfg part mh26533)

Put the humidifier number, not the solenoid number, into Google or directly at www.appliancefactoryparts.com . They show a breakdown of the humidifier and let you order replacement parts. I've just ordered the solenoid assembly, which they say is in stock.