Humidity wont go above 15% - Honeywell QuietCare HCM-630 Humidifier

It may very well be operating properly. One way to tell is to buy an inexpensive humidity gauge and check to see what the humidity level in the room is. (You rarely need extra humidity when the outside temperature is above 32°, and usually not until it drops into teh teens.)
Here's one you can pick up for $10 on Amazon.

Installed how recently, by whom? Call installer!

You should be able to get a higher humidity rate at normal settings. If you want high humidity above 40% that should be easily done with the high speed operation. The unit may need a good internal cleaning, and use a Vinegar solution to clear any Calcium or other mineral deposits from the misting ports and misting elements. You must use only Distilled or Filtered water, not tap water.

Hello, the first to confirm is if you are receiving 24 volts at the transformer, if you are then check for 24 volts going into the humidistat and out of the humidistat, if voltage is confirmed there then check if your solenoid is recieving 24 volts, if it is and the solenoid is not letting water into the humidifier than your solenoid is bad and must be replaced. If you do not have 24 volts at the transformer then turn off power to the transformer and set your meter to read continuity, you should have resistance if not the transformer is bad and must be replaced. If you have power to the humidifier and not humidifieing properly then you have to set the humidistat according to what the outdoor temp is, the outside temp determines what setting and % of humidity you should have in your home. Here is a what it should be
-20 set to 15%
-10 set to 20%
0 set to 25%
10 set to 30%
20 set to 35%
above 30 set to 40%

The higher the % of RH, (relative humidity), the more humid the house will be. I would disregard the temp part of the dial, and focus more on your comfort. Adjust it up daily until you reach a satisfactory humidity level. Hope this helps

get a humidity gauge from radio shack for about 20 bucks. thats the only way to tell. or pay a service compant tocome out for probaby a 100 bucks to tell you what the humidity level is in your home. id get the $20 one a the shack

you need to make sure your humidity level in the house isnt higher then what your humidifier will provide at any givin outdoor temp. this chart is in the owners manual. you cant remove the wires going to the ODS or it will give an error unless you have a resistor to put in its place. Anyway if the humidifier works in test mode according to AA it works so you may have higher humidity than you think, the highest your gonna get is 45% as the temp outside drops it will allow less humidity so it doesnt cause window condinsation (property damage) here is a copy of the chart. the #s on the left are the dial setting
TABLE 2 – % Relative Humidity Guide
Outdoor Temperature (°F)
-10°F 0°F 10°F 20°F 30°F 40°F
1 10% 10% 10% 15% 20% 25%
2 10% 10% 15% 20% 25% 30%
3 10% 15% 20% 25% 30% 35%
4 15% 20% 25% 30% 35% 40%
5 20% 25% 30% 35% 40% 45%
6 25% 30% 35% 40% 45% 45%
7 30% 35% 40% 45% 45% 45%

you may try running your blower 100% of the time.this should allow the humidifier to stay on even when your not heating. once the humidity level gets to where you want it, you may be able to put the fan selector back to auto. also you mentioned you have a variable blower. this is great if it is set up to run at approx. 20% fan speed when it is not heating or cooling. at 20% you can circulate enough air through the house to humidify without being able to hear the noise of the blower. it will really increase the comfort level of the house if you tend to have hot and cool spots. if it was not set up this way, contact the installer and ask if they can do this for you.

The max the aprilaire can put out is 45% Rh. Your humidifier may wired up to run only when the heat is on. In some cases this is not enough time to maintain your humidity level your seeking. To correct this, the hum. has to hooked up the hot side of the water supply. And the humidifier has to be hooked up when the fan runs and leave the fan run constantly