Central humdifier doesn't seem to work

I live in the northeast US and I have a forced-air furnace with central air and an attached humidifier but the air in the house seems dry.
The humidifier pad looked dry so I poked around a bit and found the humidistat plugged with dust and I blew it out with some compressed air. I then saw a trickle of water over the pad but a week or so later the air was still dry. I turned the humidistat up to 40% then 45% and waited a day or so each time. No (noticable) change.
Aside from foggy windows and not waking up with a dry throat, how can you tell if a humidifier is working? What else can I tweak, clean, etc. to get it working? (Or course, we're turning the corner from winter into spring and I won't want extra water in the air but at least I'll know for next winter.)
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Buy a hygrometer so you can see what the humidity is. Even a cheap one is a pretty good guide.
Keep an eye on the pad to be sure it is getting wet, that it is rotating if it is the type that does. Humidifiers are easily gunked up with minerals so it should be kept clean for best results.
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Chris wrote:

How is that again? If the pad looked dry and found the humidistat was plugged? Could you mean the valve? The humidistat should not be located near the pad - humidifier, but on the return air duct or by the thermostat.
How old is the pad. Likely it needs to be replaced.

I suggest getting one of those cheap digital meters that will display the temperature and humidity. Try some place like Brookstone or Sharper Image. It will not be 100% accurate, but close enough.
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In alt.home.repair on 16 Mar 2005 05:04:31 -0800 "Chris"

Blowing out the humidistat as you did was a good idea, but obviously didn't solve all the problems. IMO the odds are that the valve where the water goes into the humidifier is clogged. They probably sell parts to repair it, or the whole valve to repair the humidifier.
The valve/connection where the tube to the humidifier connects with a water pipe can also clog. Or it rusts into two pieces and the second piece stays stuck in the water pipe. Especially if you turn off your humidifier there each spring. (You don't run your humidifier in the summer, do you? Remember, it's automatic. You have to do something to stop it. Well, maybe not on a good one. I have el cheapo, with no motor, and it works fine except that I have to turn off the water each spring. The company that made this model seems to be gone.)
If either of these is true, or even if you're just checking them, make sure you don't have a polyethylene (translucent white plastic) tube to your humidifier. They will sprout leaks for no apparent reason (did so to my humidier and a friend's refridgerator ice maker. Good thing we were both home at the times.). Replace it with copper. Not hard. Not expensive. Plastic is NO good.

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Not sure what brand you have, but on my Aprilaire, which uses a bypass duct, there is a baffle that needs to be open or shut every heating season. If it is shut, you won't get any humidified air.
Not sure what you mean by a trickle. It should be enough to moisten the pad. Mine uses a metal grate that should be cleaned/replaced every so often.
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Is it a tumbling drum type, or a square vertical pad? Atached to the plenum, or flow through type? Float valve or electric solenoid? What brand? Waht model? How old? Does it have a drain? Does it have a pan under the evaporator pad? Is it 110 volt or 220 volt? Does it have a power source at all? Or is it mechanical?
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