Where can I find a cap-part #143-186 at.

Sounds like the high pitched noise is coming from the solenoid valve which allows water to enter the humidifier. Typically when the water pressure is too high, it causes this high pitched sound at the solenoid valve. You can adjust the water pressure a little at a time and see if it helps, just make sure you’re getting enough water across the water panel.

I read you rite,t the humidifier won't supply enough water to wet the roller . If so then follow the fresh water line down to the shut off valve. Most likely a saddle valve. with screws holding the valve tight to the side of the water pipe. I have had many of these plug up with junk in the water over time. best suggestion is to screw in the valve all way till it stops hard ,like suddenly. If it very stiff to turn the valve get a wrench and loosen the collar nut just a bit so the valve screw handle will screw in and out easier. Remember clockwise is in or OFF, and Counter clockwise is open or out. Run this valve closed and open a few times, then check the humidifier float for proper water level. Good Luck, Bill

Do you hear the solenoid click. Furnace must be on and humidistat must be up. Do you have the ability to check for 24 volts (2 wires at solenoid). Loosen copper nut at solenoid to see if water is present. (Be careful about water spraying). Loosen nut on humidifier side of solenoid. Could be small blockage in copper line at solenoid.(There is a very small orifice there that could get clogged)
Could be Humidistat also. really need voltage meter to check wiring.

the value would have been stuck inside the white cap, the valve rim should come out like an umbrella out of the cap.

With the Honeywell he220, you will use alot of water, trying to turn down the water will only reduce your amount of humidity in the home, you may be able to adjust it a little but you need to take the cover off and reduce the water flow a little at a time watching the water as it flows across the pad, you just have to make sure the humidifier pad is getting plenty of water across it, to little and you lose your humidification, hope that was helpful to ya, thanks for your question,
mr.grzz

If the unit was installed with a saddle valve, which is most often the case, you could try turning down the water pressure by tightening the valve a bit. Just follow the copper water line from the humidifier back to the main water line and look for a little valve that you can turn. Try to tighten this enough so that you still have water flowing, but at the proper volume so that it doesn't overflow and splash all over.

I've been working on the Aprilaire 110 unit today, after encountering the same problem. Here's how I fixed it: First, with the humidistat turned to 0%, I turned off the water supply saddle valve all the way (all the way to the right)--and then turned it back on all the way (all the way left). Still no water flow. Second, I slightly loosened the inline valve nut on the discharge side of the solenoid on the side of the 110 unit. Water began flowing, so I tightened it back up; and now the water flows freely. Conclusion: You may have some mineral deposit buildup in your lines, as I apparently did.

That is not a 'motor' on the side of the humidifier housing, it is a solenoid valve. The water feeds in to one side and exits the other side to a tube that feeds in to the top of the humidifier unit. The valve opens and allows water to flow when electrical power is applied to the valve

The valve electircal requirement may be either 120 vac or 24 vac. Power typically is switched on and off by a Humidistat control. The power feed to the Humidistat may come from a small transformer if the valve is a 24 vac unit, or directly from a furnace connection if the valve is a 120 vac unit. There are many variations, though.

A qualified licensed eletrician should check the power feed to the valve. If there is no power feed to the valve then he can trace back to the point of failure and correct the issue ... but he must also check for additional issues with the valve itself, as noted below.

Other possibles reasons for solenoid valve failure:

If power feed to the valve tests ok, then the coil inside the solenoid may be 'open' (bad, no continuity). The electrician can test the coil by checking resistance or continuity of the coil.

A non-electrical problem is that the valve path may be blocked by hardwater mineral build-up or other foreign material that flowed through the water line.

The solenoid valve must be replaced if either of the above is true with your valve.

Remember, use only a quailified licensed electrician!

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

check list
1.check the clamp on the pipe where water line connects
is the hole clogged (water turned off)wont take long
2.Is water flowing all the way to resevoir after turnnig water on
loosen line at reservoir
3.jiggle float water should enter the reservoir inlet to float valevel
somestime cake up,clean float off
4.Remove pump cap clean impeller and standpipe
5.clean reservoir,and close everything up

Usually the hole in the pipe is clogged up in step 1 or the float is sticking if there is no evidence of water in the reservoir