Aprilaire 112 User manual

READ AND SAVE THESE INSTRUCTIONS
Includes Safety, Operating and Maintenance
Instructions and Warranty
TABLE OF CONTENTS PAGE
Introduction ................................................Inside Front Cover
Principle of Operation ............................................................1
Operating Instructions
•Automatic Humidifier Control............................................3
•Manual Humidistat ............................................................5
Effect of Water Characteristics ..............................................6
Annual Maintenance ..............................................................7
Annual Summer Shutdown ....................................................7
Periodic Preventative Maintenance .......................................8
MAINTENANCE INSTRUCTIONS
Models 558 & 550 ..............................................................9
Models 568 & 560 ..............................................................9
Models 768 & 760 ............................................................10
Model 440 ........................................................................11
Models 448 & 445 ............................................................11
Reservoir Pump Sections .............................................12
Models 350 & 360 ............................................................13
Models 110 & 112 ............................................................14
Models 220 & 224 ............................................................15
Limited Warranty..................................................................16
Replacement Record ............................................Back Cover
HUMIDIFIERS
The Best Cure For Dryness®
®
FOR MODELS 768, 760, 568, 560, 558, 550,
448, 445, 360, 350, 110, 112, 220, 224, & 440
OWNER’S MANUAL

WARNING! 120 volts may cause injury from
electrical shock. Disconnect power and shut off
water supply before servicing.
CAUTION! Sudden operation may cause
personal injury or property damage. Turn
humidistat or Automatic Humidifier Control,
to “OFF” or lowest setting before servicing
Replacement Water Panel evaporators are available from your installing con-
tractor or from most other local heating and air conditioning contractors in
your area. However, if you still have difficulty in obtaining a replacement Water
Panel evaporator, use the dealer locator in our web site (www.aprilaire.com)
or look in the Yellow Pages under Humidifying Apparatus or Heating & Air
Conditioning Contractors.
© Research Products Corporation 2000
INTRODUCTION
Thank you for your recent Aprilaire®Humidifier
purchase. We sincerely appreciate your business and
are pleased to add your name to our growing list of
customers. With this purchase, you have invested in the
highest quality equipment currently available. Research
Products Corporation is the largest manufacturer of
whole house humidifiers, air cleaners and fresh air
exchangers and is a recognized leader in the heating
and air conditioning industry today.
Please be assured that in addition to product quality,
we are also committed to unit performance as well as
customer satisfaction. Your unit will require periodic
maintenance to assure you of continued fine performance.
Please proceed as shown on page 7 to obtain service
parts and/or replacement Water Panel®evaporators.
Now, please take a few minutes and read the
appropriate section of this booklet. This will familiarize
you with the benefits you will receive from the equip-
ment you just purchased and help you understand the
routine maintenance that will be required. Be sure to
register your warranty with us for our records and your
protection. You may do so by returning the Warranty
Information Card to us, or you can register online at:
www.aprilaire.com/warranty.

I. PRINCIPLE OF OPERATION
With your purchase of a humidification system, you have
invested in a humidifier that operates on the evaporative
principle – nature’s own way of adding moisture – and will
provide the proper relative humidity all during the heating
season. It is very possible that you have questions concerning
your new humidifier – questions on what it can do for you, and
what you should do to receive maximum benefits from it. This
booklet is intended to help you do exactly that.
Nature, in producing an invigorating comfortable April day,
combines just the right temperature and the right amount of
moisture. Aprilaire Humidifiers employ the same principle, with
refinements, to give you the proper relative humidity for maxi-
mum allowable comfort all winter long.
The important considerations in the evaluation of a humidifier
are Positive Control, Sufficient Capacity, Trouble-free
Performance and Minimum Maintenance. The operating
principle of your Aprilaire provides all of these advantages.
Here, briefly, is the method:
The Aprilaire Humidifier (except the Models 350 and 360) is
installed to operate in conjunction with the furnace blower
motor. When the humidistat or Automatic Humidifier Control
calls for humidity and the blower motor is operating, water flows
to the distribution pan located at the top of the unit. The water is
uniformly distributed across the width of the pan and through a
scientifically designed system of outlets. It flows by gravity over
the Water Panel
®
evaporator, the heart of the unit. Dry, hot air is
moved through the moisture-laden Water Panel evaporator
where the evaporation takes place. The now humidified air
carrying moisture in vapor form (nature’s own way) is circulated
throughout the home.
The Models 350 and 360 use service hot water (140°F maxi-
mum) for its heat source, as heat is needed for evaporation.
While the water going to the unit is hot, the flushing water to the
drain will be cold. The heat is extracted during the evaporation
process.
The correct water flow is determined by an orifice
equipped with each drain type unit. When the unit is operating,
there will be a small, steady stream of water to drain, which
flushes away most of the trouble-causing minerals. Do not
use the saddle valve to regulate the water flow. It is designed to
be completely opened or closed. The minerals and solid residue
®
Your Humidifier
- 1 -

- 2 -
not trapped by the replaceable Water Panel evaporator are
flushed down the drain. The drain also eliminates the problems
caused by stagnant water. This is the most effective and least
expensive method to dispose of trouble-causing minerals.
There are some homes where drain facilities are not accessi-
ble or available. For these situations, or where high water
hardness is not a problem, specially designed Aprilaire
Humidifiers, Models 448 and 445, are available, incorporating
a water recirculating system.
Capacity is high because an average-size home (10,000 cu. ft.)
requires the addition of approximately 9 gallons of water
per day to maintain
35% relative humidity when the outside
temperature is 20°. The smallest Aprilaire Humidifier under most
operating conditions, has this humidifying capacity. Trouble-
free performance and minimum maintenance are assured by
the design features of the Aprilaire Humidifier. All unit hous
ing
parts that come in contact with water are non-metal and will
never rust
or corrode. Neither heat nor water will affect them
under normal operating conditions.
The Water Panel evaporator, designed especially for uniform,
high evaporation, and the Scale Control Insert also efficiently
traps mineral deposits which are often the cause of damage to
working parts in ordinary humidifiers. No “white dust” can be
distributed throughout the living quarters. The Water Panel evap-
orator is the heart of the unit and must be in good condition to
assure high capacity trouble-free performance. It should be
changed annually.
The granular coating in the bottom of the distribution tray is
designed to provide equal distribution of the water to each of the
openings assuring an even flow of water over the Water Panel
evaporator. Do not clean the mineral scale off the bottom of the
water distribution tray at the end of the humidification season.
The scale itself provides an excellent track for the water to follow.
This is actually what we try to simulate with the synthetic coating
in the bottom of the tray. If the coating is removed, it is not necessary
to purchase a new distribution tray or upper housing. You can
accomplish the same uniform performance by applying a small
amount of liquid dishwashing detergent over the entire lower surface
of the water distribution tray. This will allow the water to flow
evenly through each of the openings, provided, of course, the
unit is level in order to achieve maximum capacity.
There are many humidifiers on the market. They all add
moisture . . . with varying degrees of efficiency. None, however,
can provide the features, design, and performance incorporated
into your Aprilaire Humidifier.

II. OPERATING INSTRUCTIONS
Automatic Humidifier Control: (Manual humidistat-see pg 5)
Your Automatic Humidifier Control is installed in the cold air return.
During the first heating season, your Automatic Humidifier Control
needs to be set initially to match your home’s condition. Please
follow these steps when adjusting your control (refer to Figure A).
1.Turn the dial setting knob to “5,” which is within the normal
range. During the next 24-48 hours it may be necessary to
adjust the dial for more or less humidity, depending on your
personal comfort and home’s requirements. Refer to the
“Operation Guide” (Table 1).
2.During the coldest portion of the first heating season, minor
adjustments may be necessary. This is dependent upon
your individual home construction, refer to the “Operation
Guide” (Table 1).
- 3 -
(Table 1) Operation Guide
Condition Solution
Condensation on windows Reduce the setting on the control dial
by 1 increment.
Lack of humidity Increase the setting on the control dial
by 1 increment.
Humidifier does not operate Turn dial to “Test.” Make certain furnace
blower is operating and furnace is calling
for heat. If unit still doesn’t operate, consult
a heating contractor.
Humidifier won’t shut off Turn dial to “Off.” If unit continues to
operate, consult a heating contractor.
Test mode System operation is checked by setting the
knob to“Test.” Make certain furnace blower
is operating and furnace is calling for heat.
Humidifier will operate for one minute.
Off
7
6
5
4
3
21
T
e
s
t
N
O
R
M
A
L
Humidity Level
(Figure A)
The relative humidity in your
home will now be accurately
controlled to meet your needs
and should not need further
adjustment during future
heating seasons. Make note of
the dial setting in the event you
temporarily move the knob
when performing annual
maintenance of the Aprilaire
Humidifier.

Your Aprilaire Automatic Humidifier, is a high precision system
that will accurately maintain the relative humidity in your home.
For every 1º change in outdoor temperature, the control will
automatically adjust the indoor relative humidity (RH) by 1⁄2%.
If you would like to determine the RH in your home, follow
these steps:
1. Determine the outdoor temperature.
2. Activate the furnace blower by setting your thermostat fan
switch to the “On”position, or setting your thermostat to a
higher temperature.
3. Turn the control dial setting to the “Off”position. Then,
slowly turn the dial clockwise until you hear the solenoid
valve “click on.”Next, slowly turn the dial counter
clockwise until you hear the solenoid valve “click off.”At
this point, make note of the dial setting.
4. Locate your dial setting on Table 2. Follow the dial setting
to the right until it intersects with the current outdoor
temperature. This is the relative humidity in your home
under existing conditions.
5. Return the thermostat and the control to their original
settings.
The Automatic Humidifier will accurately control the humidity
in your home to a maximum of 45% RH and a minimum of
10% RH. The values of outdoor temperature and dial settings
may fall in between or outside of the listed values in Table 2. In
these cases, you can only approximate your home’s actual
indoor RH.
As an example, if the outdoor temperature is 20ºF, and, following step 3, the
humidifier turns off at “5”on the dial range, then the RH in your home is 35%.
- 4 -
(Table 2) % Relative Humidity Guide
-10 0 10 20 30 40
1 101010152025
2 101015202530
3 101520253035
4 152025303540
520253035 40 45
6 253035404545
7 303540454545
Outdoor Temperature (ºF)
Dial Setting

- 5 -
Manual Humidistat:
(Automatic Humidifier Control – see pg 3)
Your new Aprilaire Humidifier is controlled by a humidistat
installed either in the living area or in the cold air return. It is
important to anticipate a drop in outdoor temperature and reduce
the setting accordingly to avoid excessive condensation. For
example, with an outdoor temperature of 20°the correct setting
will be 35% relative humidity. If the temperature is expected to
fall to 0°that evening, then merely reduce the setting to 25%
several hours prior to the temperature change.
The recommended settings on the humidistat are based on
years of research (see table 3) and experience as to what is best
for the average home. These settings represent a compromise
between RH levels that would be most desirable for comfort
reasons and humidity levels that are suitable for protection of
your home. For example, a wintertime indoor RH of 50% may be
considered ideal, but unfortunately, it probably would result in
damage to your home. Observance of the recommended RH
levels on your humidistat, therefore, is an important safeguard.
Condensation of water on inside windows in the form of fogging
or frost is usually an indication of too high relative humidities.
This same condensation can take place in other areas in your
home with the possibility of damage resulting.
Outside Temperature Recommended RH
+40°45%
+30°40%
+20°35%
+10°30%
0°25%
–10°20%
–20°15%
(Table 3) Outdoor-Indoor Relative Humidity
The humidistat is a precision instrument that can be used
to determine the RH accurately in your home during the winter.
Turn the dial to the lower setting, then reverse the dial direction
slowly until a “click”is heard. At this point, read the RH on the
dial. This will be very close to the actual RH in your home.

- 6 -
To check the humidifier operation, set the humidistat above
the click point, make sure that the water saddle valve is open and
that there is electricity to the unit. Generally, with all models
except the 350 and 360 Aprilaire Humidifiers, the furnace blower
motor must be operating for the Aprilaire Humidifier to function.
After the humidifier has operated for several minutes and water
is entering the unit and coming out at the drain, reduce
the humidistat setting below the click point and the unit should
automatically shut off. Now set the humidistat dial at the recom-
mended inside relative humidity, depending on the outside
temperature. Follow the suggested settings prior to a drop in the
outside temperature.
Additional Information
Be sure to keep fireplace dampers closed when not in use.
They provide an excellent escape route for heat, as well as
humidity. Humidity is lost at an even faster rate than heat
because water vapor tends to seek its own level and your
humidifier would not be able to replace it even when running
at full capacity.
On occasion, indoor moisture producing activities such as
clothes drying, cooking, showers, etc., may raise the relative
humidity level higher than it should be, even though the
Aprilaire Humidifier is not operating. Telltale indications, again,
are condensation or frost on cold surfaces such as windows,
doors, walls, etc. If such condensation persists for several
hours, your home should be ventilated to dissipate the poten-
tial damaging excess moisture levels.
III. EFFECT OF WATER CHARACTERISTICS
Your humidifier will operate effectively using either hot, cold,
hard or mechanically softened water. Whether to use available
tap water, even though it may be quite hard, or chemically soft-
ened water, is a common concern to homeowners when installing
a humidifier.
Water used in homes contains varying amounts of minerals.
The residue remaining as a result of hard water evaporation is pri-
marily calcium and magnesium components and is usually quite
hard, scaly, and dense.
Residue from softened water tends to be soft and fluffy and has a
greater volume than hard water scale. The service life of a Water
Panel evaporator may be extended by using hard water, but in

- 7 -
either case, the Water Panel evaporator is usually changed once
a year. In the Models 448 and 445 Aprilaire Humidifiers, these
solids will build up on the evaporator surface, in the reservoir
and pump section. This is why proper maintenance is important
and necessary. Service hot water, 140°maximum, is recom-
mended with drain type units for increasing capacity and for
heat pump applications.
In the drain-equipped models, most of these solids are effec-
tively controlled by flushing them down the drain.
IV. ANNUAL MAINTENANCE
For best performance, we recommend that you replace the
water panel evaporator in your Aprilaire Humidifier annually.
•Call the installer of your Aprilaire Humidifier. This information is
often found on your equipment.
•Call your heating and air conditioning dealer.
•Use our “Dealer Locator”at: www.aprilaire.com
•Look in the Yellow Pages under Humidifying Apparatus
or Heating & Air Conditioner Contractors.
•If none of the above is successful and you still need
information, please feel free to write us.
V. ANNUAL SUMMER SHUTDOWN
For Models 220, 224, 440, 445, 448, 550, 558, 560, and 568
close the bypass damper if provided. For the Models 445 and
448, empty the reservoir.
AUTOMATIC HUMIDIFIER CONTROL:
Humidifiers controlled by the Automatic Humidifier Control
require no control adjustment. Shut off the water supply to the
humidifier by closing the saddle valve.
MANUAL HUMIDISTAT:
Humidifiers controlled by a manual humidistat, simply turn the
humidistat to the “Off”position. Shut off the water supply to the
humidifier by closing the saddle valve.

- 8 -
Inspection and
Service Instructions
1. Disconnect electrical power to the furnace
and shut off water supply.
2. Disconnect the water line at the inlet com-
pression nut.
3. Remove the in-line strainer from inside the
inlet fitting by using a small nail or wire.
4. Flush the in-line strainer clean or replace
with a new strainer, Service Department,
Part No. 4004.
5. Replace the in-line strainer and reconnect
the inlet water line (Double Wrench To
Prevent Leaking).
6. Disconnect the water line at the outlet com-
pression nut.
7. Remove the orifice from the copper or plas-
tic tube and make sure this small opening is
unplugged.
8. Replace the orifice and reconnect the outlet water line (Double Wrench
To Prevent Leaking).
9. Turn on water supply and reconnect electrical power to the furnace.
VI. PERIODIC PREVENTATIVE MAINTENANCE
NOTE: Periodic inspection and preventive maintenance
of your total heating system is important for efficient and safe
operation. Your heating contractor should include humidifier
service at the same time.
All models, except No’s. 448 and 445, are equipped with
an in-line water strainer and orifice as shown below. These parts
should be inspected and cleaned periodically to assure contin-
ued proper unit performance.

- 9 -
MODELS 558-550-568-560
1. Note humidistat or control setting and turn dial to the “OFF”position.
2. Turn off water supply.
3. At the side of the unit opposite the airflow duct pull front cover (1) off hold-
ing with both hands and set aside.
4. Carefully pull the plastic feed tube (2) out of the nozzle (3) at the top of the
Water Panel evaporative assembly (4). Pull this assembly out by grasping at
top and tipping out.
5. Remove the black plastic distribution tray (5) from the evaporative assembly
by unsnapping the white plastic holding strips from the tabs at the end of
the tray. Lightly scrape out any calcium deposits and clean the “V”notches
(6), but do not scrape off the granular coating from the bottom. This
textured surface helps ensure even water flow for maximum performance.
See page 2 if removed.
6. Slide the Water Panel evaporator (7) out from the white plastic Scale
Control Insert (8). Clean the insert frame by twisting and flexing it to loosen
the calcium deposits, or use a putty knife. Inspect the Water Panel evapo-
rator (Stock No. 10 for Model 550 and Stock No. 35 for Model 560) and
substitute a new one if necessary. Slide the pad back into the insert frame
with the black colored spot up and snap the black distributor tray back into
place.
7. Re-install the Water Panel evaporative assembly into the unit by fitting its
drain tube into the round receptacle at the base of the unit. Push the
assembly in at the top against the beveled tabs that will hold it in place.
Push the end of the feed tube back firmly into the nozzle and replace the
front cover.
8. Remove the drain hose (9) from the bottom of the unit and bend and flex it
to loosen the internal calcium deposits. Then flush it with water under pres-
sure and slip it back onto the black drain fitting.
9. Turn on water supply.
10. Check system operation:
Manual Humidistat: Turn up humidistat to highest setting and make sure
the furnace blower is operating. Humidifier will operate if RH is less than
50%.
Automatic Humidifier Control: Check system operation by setting the
knob to “Test.”With furnace blower operating and furnace calling for
heat, humidifier will operate for one minute.
11. Set humidistat or Control to its original position.
MAINTENANCE INSTRUCTIONS
for
APRILAIRE HUMIDIFIER MODELS 558-550-568-560
CAUTION! Sudden operation may cause personal injury or property damage. Turn
humidistat or control to “off” or lowest setting before servicing.
1. Front Cover
2. Feed Tube
3. Nozzle
4. Water Panel Evapo-
rative Assembly
5. Distribution Tray
6. ”V”Notches
7. Water Panel
8. Scale Control Insert
9. Drain Hose
1
56
8
9
1
2
34

- 10 -
MODELS 768-760
1. Note humidistat or control setting and turn dial to the “OFF”position.
2. Disconnect electrical power and turn off water supply.
3. Unlatch humidifier cover assembly (1) from base assembly (2) at the bottom of the
cover, lift, and set aside.
4. Pull out the evaporative assembly (3) by grasping at the top and tipping out.
5. Remove the black distribution tray (4) from the evaporative assembly (3) by unsnap-
ping the white plastic holding strips from the tabs at the end of the tray. Lightly scrape
out any calcium deposits and clean the “V”notches (5) but do not scrape off the
granular coating from the bottom. This textured surface helps ensure even water
flow for maximum performance.
6. Slide the Water Panel evaporator (6) out from the white plastic scale control insert (7).
Clean the insert frame by twisting and flexing it to loosen the calcium deposits or use
a putty knife. Replace Water Panel evaporator annually with a new Water Panel evapo-
rator (Stock No. 35). Slide the Water Panel evaporator back into the scale control insert
with the red colored spot up and snap the black distribution tray (4) back into place.
7. Re-install the evaporative assembly (3) into the base assembly (2). Push the evaporative
assembly (3) in at the top between the retaining ribs that hold the assembly in place in
a vertical position.
8. Remove the drain hose (8) from the bottom of the unit. Bend and flex it to loosen the
internal calcium deposits. Then flush it with water under pressure and slip it back onto
the drain fitting.
9. Reinstall cover assembly (1) by hooking at the top of the base assembly (2) and
latching at the bottom.
10. Reconnect electrical power (9) and turn on the water supply.
11.
Check system operation:
Manual Humidistat: Turn up humidistat to highest setting and make sure the
furnace blower is operating. Humidifier will operate if RH is less than 50%.
Automatic Humidifier Control: Check system operation by setting the knob
to “Test.”With furnace blower operating and furnace calling for heat,
humidifier will operate for one minute.
12.
Set humidistat or control to its original position .
MAINTENANCE INSTRUCTIONS
for
APRILAIRE HUMIDIFIER MODELS 768-760
WARNING! 120 volts may cause serious injury from electrical shock. Disconnect
power and shut off water supply before servicing.
1. Front Cover
2. Base
3. Evaporative
Assembly
4. Distribution Tray
5. ”V”Notches
6. Water Panel
7. Scale Control Insert
8. Drain Hose
9. Power Cord
4
5
6
7
8
9
1
2
3

MODELS 440-448-445
MAINTENANCE INSTRUCTIONS for
APRILAIRE HUMIDIFIER MODEL 440
CAUTION! Sudden operation may cause personal injury or property damage. Turn
humidistat to “off” or lowest setting before servicing.
1. Note humidistat setting and turn dial to the “Off”position.
2. Remove two aluminum knobs (1), swing up and remove top cover (2) from
humidifier.
3. Place finger under white plastic water outlet (3) at top of black water distribution
pan (4). Lift up to pop outlet loose from hole and notch in black distribution pan.
4. Tip forward and lift the complete plastic framed evaporative assembly out of the
humidifier.
5. To remove black plastic water distribution pan from evaporative assembly,
push down on pan and out on white plastic frame (Scale Control Insert). Clean “V”
openings in water distribution section of upper housing but do not scrape off
granular coating from bottom. This helps to ensure proper even water flow for
maximum performance.
6. Remove Water Panel evaporator from Scale Control Insert and clean Insert by flexing
or using putty knife. Inspect Water Panel evaporator (Stock No. 12) and replace if
necessary with colored spot up. Snap plastic water distribution pan back in place.
7. Reinstall evaporative section
in the humidifier with notch
and hole in black plastic
water distribution pan
toward you. Pop nozzle fit-
ting on end of feed tube into
black plastic water distribu-
tion pan.
8. To reinstall top cover, hook
back under lip of metal frame
(5), drop in place and tighten
two aluminum knobs.
9. Remove drain hose and flush
with water under pressure.
Lime in hose may be loos-
ened by flexing hose.
10. Reattach drain hose.
11. Turn up humidistat to highest
setting and make sure the
furnace blower is operating.
Humidifier will operate if RH
is less than 50%.
12. Set humidistat to its original position.
MAINTENANCE INSTRUCTIONS for
APRILAIRE HUMIDIFIER MODELS 448-445
WARNING! 120 volts may cause serious injury from electrical shock. Disconnect
power and shut off water supply before servicing.
1. Note humidistat or control setting and turn dial to the “Off”position.
2. Disconnect electrical power and turn off water supply.
3. Remove two aluminum knobs (1), swing up and remove top cover (2) from humidifier.
4. Place finger under white plastic water outlet (3) at top of black water distribution pan
(4). Lift up to pop outlet loose from hole and notch in black distribution pan.
5. Tip forward and lift the complete plastic framed evaporative section out of the humidifier.
6. To remove black plastic water distribution pan from evaporative section, push down
on pan and out on white plastic frame (Scale Control Insert). Clean “V”openings in
water distribution panel but do not scrape coating off bottom surface.
7. Remove Water Panel evaporator and Scale Control Insert. Remove Water Panel
evaporator from Insert and clean insert by flexing or using putty knife. Inspect Water
Panel evaporator and replace with a new Water Panel evaporator, if necessary, with
colored spot up.
8. Re-install black water distribution pan. Reinstall evaporative section in the humidifier,
with notch and hole in distribution pan toward you. Pop hose fitting on end of feed
tube into distribution pan.
9. See page 12 for reservoir and pump cleaning.
MODELS
440, 448 & 445 1. Cover Knob
2. Top Cover
3. Feed Nozzle
4. Distribution Tray
5. Metal Frame
3
4
5
1
2
1
- 11 -

A. TO CLEAN RESERVOIR
1. Hold bottom of reservoir (IT IS FILLED WITH WATER) and loosen retainer
knob. Carefully lower reservoir, disengaging from metal frame.
2. Empty water, remove partition and reservoir liner.
3. Clean or replace reservoir liner. Reinstall partition in liner. To replace
reservoir, hook back of reservoir over lip of dark metal frame and
tighten knob.
B. TO CLEAN HOSE
1. Disconnect hose from pump and pull hose up through hole.
2. Flex hose to loosen scale and flush clean with a stream of water.
3. Clean nozzle at the same time.
C. TO CLEAN PUMP
1. Remove pump impellor cap (1) by pushing down on projecting sides (2).
2. Clean scale from inside of cover and impellor (3) with dull blade.
3. Clean flow control (4) in pump outlet with 5/32”bit.
4. Snap pump impellor cap (1) back in place.
5. Pull water hose down through hole, connect to pump, and attach
nozzle into water distribution pan.
D. TO CLEAN FLOAT
1. Clean scale off float (5) and arm mechanism (6) with dull blade.
2. Work arm mechanism (6) up and down to dislodge any scale buildup.
E. TO OIL MOTOR
1. Disconnect water line at valve inlet and swing line free. Disconnect
the humidistat leads.
2. Remove the three screws from the brown motor cover and remove.
3. Use two drops SAE 20 oil in the yellow hole on top and inside the
yellow mark on the side of the motor.
F. TO REASSEMBLE
1. Replace motor cover.
2. To reinstall reservoir, hook back of reservoir over lip of dark brown
metal frame and tighten knob.
3. Reconnect water at valve inlet.
4. To reinstall top cover, hook back under lip of dark brown metal
frame and tighten two knobs.
5. Reconnect humidistat or control leads and electrical power.
6. Turn on water supply and fill reservoir in the fall.
7. Check unit operation.
8. Check system operation:
Manual Humidistat: Turn up humidistat to highest setting and make
sure the furnace blower is operating. Humidifier will operate if RH is
less than 50%.
Automatic Humidifier Control: Check system operation by setting the
knob to “Test.”With furnace blower operating and furnace calling for
heat, humidifier will operate for one minute.
9. Set humidistat or Control to its original position.
- 12 -
MAINTENANCE INSTRUCTIONS
FOR MODELS 448-445
RESERVOIR PUMP SECTIONS
WARNING! 120 volts may cause serious injury from electrical shock. Disconnect
power and shut off water supply before servicing.
IMPORTANT: Clean and refill reservoir, hose, pump and float every 30 days during
heating season.
1. Pump Impellor Cap
2. Cap Sides
3. Impellor
4. Cap Flow Control
Opening
5. Float
6. Arm Mechanism
6
2
1
3
4
5
2

- 13-
1. Disconnect electrical power and turn off water supply.
2. Remove screws of the inlet grille (1). The grille can now be removed
from the metal housing (8).
3. Lift the complete plastic framed evaporative section out of the humidifier
housing.
4. To remove the distribution tray (2) from evaporative assembly (9), push
down on tray and pull out on white plastic frame (Scale Control Insert)
(3). To clean the “V”openings of the tray, it will be necessary to gently
pry the distribution tray cover (4) from the tray. In this cleaning procedure
do not scrape off the granular coating from the bottom of the tray.
This helps insure proper, even waterflow for maximum performance. See
page 2 if removed.
5. Remove Water Panel evaporator (5) from the Scale Control Insert (3).
Scrape the Insert with a putty knife or similar tool and flush clean with
water. Install new Water Panel evaporator (Stock No. 35) with black
colored spot up. Snap plastic cover into tray and tray into Scale
Control Insert.
6. Remove the drain hose from the bottom of the unit and bend and flex it
to loosen the internal calcium deposits. Then flush it with water under
pressure and slip it back onto the black drain fitting (6).
7. Re-install complete plastic framed evaporative section and intake grille.
8. Reconnect electrical power.
9. Turn on water supply and check unit operation.
MAINTENANCE INSTRUCTIONS
for
APRILAIRE HUMIDIFIER MODELS 350-360
WARNING! 120 volts may cause serious injury from electrical shock. Disconnect
power and shut off water supply before servicing.
1. Inlet Grille
2. Distribution Tray
3. Scale Control Insert
4. Distribution Tray Cover
5. Water Panel
6. Drain Spud
7. Power Cord
8. Metal Housing
9. Evaporative Assembly
3
4
5
6
7
8
9
1
2
MODELS 350-360

- 14 -
MODELS 110-112
1. Disconnect electrical power and turn off water supply.
2. Disconnect: a) 120 volt electrical service. b) Copper water supply line
(1) & feed tube (2). c) Drain line. d) 24 volt leads.
3. Turn two swing locks (3), one at either side of lower housing off humidifier
flange.
4. Lift humidifier straight up until bottom of unit clears lip of lower housing.
Pull unit out at bottom, lower and remove.
5. Slide off three closure clips (4 & 5) that holds 2 halves of unit together.
6. Remove upper half of unit.
7. Remove Water Panel evaporator and Scale Control Insert. Remove
Water Panel evaporator from Insert and clean Insert by flexing or using
putty knife. Inspect Water Panel evaporator and replace with a new
Water Panel evaporator (Stock No. 10 for Model 110 and Stock No. 12
for Model 112), with colored spot up.
8. Remove the plastic drain hose from the bottom of the unit and bend
and flex it to loosen the internal calcium deposits. Then flush it with
water under pressure and slip it back onto the black drain fitting.
9. Remove the water distribution pan cover (6) and clean “V”openings
in water distribution section but do not scrape off granular coating
from bottom. This helps to insure proper, even water flow for maximum
performance. See page 2 if removed.
10. Oil motor with 2 drops of SAE 20 oil in oil holes at each end of motor
housing.
11. IMPORTANT: When installing Scale Control Insert and Water Panel
evaporator in the humidifier, the Insert spout must discharge directly
into unit drain.
12. Reassemble unit, position feed tube in compression fitting, tighten
compression nuts and secure copper feed tube to upper housing with
feed tube clamp.
13. In reverse order, complete steps 1 and 4 to reinstall your humidifier,
and check unit operation.
MAINTENANCE INSTRUCTIONS
for
APRILAIRE HUMIDIFIER MODELS 110-112
WARNING! 120 volts may cause serious injury from electrical shock. Disconnect
power and shut off water supply before servicing.
1. Water Supply Line
2. Feed Tube
3. Swing Locks
4. Closure Clip
5. Closure Clip
6. Distribution Pan Cover
3
4
6
1
2
4
5

- 15 -
MODEL 220-224
1. Turn off water supply and turn down humidistat.
2. Remove three “Z”clips (1) that hold top half of unit to furnace plenum.
3. Slide off four closure clips (2 & 3) that hold two halves of unit together.
4. Loosen compression fitting (4) on copper feed tube (6) and remove.
5. Remove top screw holding sheet metal elbow to humidifier.
6. Remove top half of unit (lift straight up).
7. Remove the water distribution pan cover (5) and clean “V”openings in
water distribution section but do not scrape off granular coating
from bottom. This helps to insure proper, even water flow for maximum
performance. See page 2 if removed.
8. Remove Water Panel evaporator and Scale Control Insert. Remove
Water Panel evaporator from Insert and clean Insert by flexing or using
putty knife. Inspect Water Panel evaporator and replace with a new
Water Panel evaporator (Stock No. 10 for Model 220 and Stock No. 12
for Model 224), with colored spot up.
9. Remove the drain hose from the bottom of the unit and bend and flex it
to loosen the internal calcium deposits. Then flush it with water under
pressure and slip it back onto the black drain fitting.
10. IMPORTANT: When installing the Scale Control Insert and Water Panel
evaporator in the humidifier, the Insert spout must discharge directly
into unit drain.
11. Reassemble unit, position feed tube in compression fitting, tighten
compression nuts and secure copper feed tube to upper housing with
feed tube clamp. Attach to furnace plenum.
12. Turn on water supply, turn up humidistat and check unit operation.
MAINTENANCE INSTRUCTIONS
for
APRILAIRE HUMIDIFIER MODELS 220-224
CAUTION! Sudden operation may cause personal injury or property damage.
Turn humidistat to “off” or lowest setting before servicing.
1. “Z”Clip
2. Closure Clip
3. Closure Clip
4. Compression Fitting
5. Distribution Pan Cover
6. Feed Tube
33
4
5
6
1
1
22

- 16 -
LIMITED WARRANTY
Your Research Products Corporation Aprilaire®Humidifier
unit is expressly warranted for one (1) year from date of instal-
lation to be free from defects except, however, for the
disposable water panel which will have to be replaced from
time to time depending upon the amount of use.
Research Products Corporation’s exclusive obligation
under this warranty shall be to supply, without charge, a
replacement for any part of the humidifier which is found to
be defective within one (1) year period and which is returned
not later than thirty (30) days after said one (1) year period by
you to either your original supplier or to Research Products
Corporation, Madison, Wisconsin 53701, together with the
model number, manufacturing code number and installation date
of the humidifier.
THIS WARRANTY SHALL NOT OBLIGATE RESEARCH
PRODUCTS CORPORATION FOR ANY LABOR COSTS
AND SHALL NOT APPLY TO DEFECTS IN WORKMANSHIP
OR MATERIALS FURNISHED BY YOUR INSTALLER AS
CONTRASTED TO DEFECTS IN THE HUMIDIFIER ITSELF.
IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE SHALL BE LIMITED IN
DURATION TO THE AFORESAID ONE YEAR PERIOD.
RESEARCH PRODUCTS CORPORATION’S LIABILITY
FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES, OTHER
THAN DAMAGES FOR PERSONAL INJURIES, RESULTING
FROM ANY BREACH OF THE AFORESAID IMPLIED WAR-
RANTIES OR THE ABOVE LIMITED WARRANTY IS EXPRESSLY
EXCLUDED. THIS LIMITED WARRANTY IS VOID IF DEFECT(S)
RESULT FROM FAILURE TO HAVE THIS UNIT INSTALLED BY A
QUALIFIED HEATING AND AIR CONDITIONING CONTRACTOR.
IF THE LIMITED WARRANTY IS VOID DUE TO FAILURE TO USE
A QUALIFIED CONTRACTOR, ALL DISCLAIMERS OF IMPLIED
WARRANTIES SHALL BE EFFECTIVE UPON INSTALLATION.
Some states do not allow limitations on how long an
implied warranty lasts or the exclusion or limitation of inciden-
tal or consequential damages so the above exclusion or
limitations may not apply to you.
This warranty gives you specific legal rights and you may
also have other rights which vary from state to state.

The Aprilaire®Indoor Air Comfort System is an integrated group
of air quality enhancement products designed to work with your
heating and cooling system to make your home more comfortable.
For the best in indoor air quality, ask your heating and cooling
contractor about these fine Aprilaire products, or visit us
at www.aprilaire.com to solve your Indoor Air Comfort needs.
Aprilaire®
Automatic Humidifiers
The Best Cure For Dryness®
The world’s first computer-equipped,
completely automatic humidifier.
Aprilaire®
High Efficiency Air Cleaners
Nobody Makes Clean Air Easier®
Delivers the cleanest, healthiest air ever
available from a whole-house air cleaner.
THE BEST IN INDOOR AIR COMFORT
®
Aprilaire®
Zone Control Systems
Custom Comfort Throughout Your Home®
The most reliable way to achieve temperature
control in every area of your home.
Aprilaire®
Fresh Air Exchangers
Only The Freshest Homes
Have April Air™
Your best value for a constant,
controlled supply of fresh air with
energy-recovery.
Aprilaire®
Electronic Thermostats
Energy Efficiency Never
Looked So Good™
Ultra-thin, easy-to-use digital,
programmable, and communicating
controls featuring pinpoint accuracy.

SERVICE AND WATER PANEL
REPLACEMENT RECORD
Date Dealer Name
DP #10003882 5.9.00 Printed in U.S.A.
P.O. BOX 1467 •MADISON, WI 53701-1467
Products For Better Indoor Air Quality™