
Maintenance Instructions: 
Aprilaire Model 110 Humidifier 
 
1. Note manual humidifier control setting and turn dial to the "off" position. 
2. Disconnect electrical power, turn water supply off. 
3. Disconnect 
a. 120 volt electrical service. 
b. Copper Water Supply Line (1) and feed tube (2). 
c. Drain line. d) 24 volt leads. 
4. Turn two swing locks (3), one at either side of the lower housing of humidifier 
flange 
5. Lift humidifier straight up until bottom of t humidifier clears lip of lower 
housing. Pull humidifier out at bottom, lower and remove. 
Slide off three closure clips (4 & 5) that hold 2 halves of humidifier together. 
6. Remove upper half of humidifier. Remove water distribution pan cover (6) 
and remove any mineral deposits from the "V" notches. DO NOT scrape off 
granular coating from the bottom. This textured surface helps ensure even 
water flow for maximum performance. If the granular coating has been 
removed. Place several drops of liquid dishwashing soap on the distribution 
tray. This will only need to be done once if there is no granular coating. 
7. Remove water panel evaporator and scale control insert 
8. Remove water panel evaporator from insert and clean insert by flexing or 
using putty knife. If scale control insert is not used, contact your dealer 
about obtaining one. 
9. Install a new water panel evaporator with colored spot UP, in scale control 
insert. IMPORTANT: when installing scale control insert and water panel 
evaporator into the humidifier, the insert spout must discharge directly into 
the drain. 
10. Remove drain line (7) from the bottom of the humidifier. If applicable, flex it 
to loosen any mineral deposits or blockages. Then flush it with water under 
pressure. If it does not properly clear, replace it. Slip the drain line back onto 
the drain fitting. Make sure the drain line has a constant downward slope and 
is not flattened or blocked.