Aprilaire 600 & 700 User 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
the Aprilaire Humidifier Control to “OFF” or
lowest setting before servicing
Genuine Replacement Water Panel evaporators are available from your
installing contractor 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. Purchase only genuine Aprilaire
Water Panels to maintain performance.
© 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, com-
bines 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 maximum allowable com-
fort 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 is installed to operate in conjunction with
the furnace blower motor. When the Aprilaire Humidifier Control
calls for humidity and the blower motor is operating, water flows to
the distribution tray located at the top of the unit. The water is uni-
formly distributed across the width of the tray and through a scien-
tifically 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 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 not trapped by the replace-
able 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.
- 1 -

- 2 -
There are some homes where drain facilities are not accessible
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 temper-
ature is 20°. The smallest Aprilaire Humidifier under most operating
conditions, has this humidifying capacity. Trouble-free perfor-
mance and minimum maintenance are assured by the design fea-
tures of the Aprilaire Humidifier. All unit housing 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 con-
ditions.
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 evaporator 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 evap-
orator. 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 actu-
ally 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 dish-
washing detergent over the entire inside surface of the water distribu-
tion 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
There are 2 possible modes of operation of your Aprilaire Humidifier
Control and an explanation of both modes follows:
Automatic Mode:
(Manual Mode-see pg 5)
Your Aprilaire Humidifier Control is installed in the cold air return.
During the first heating season, your 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.

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.
- 4 -
Off
7
6
5
4
321
T
e
s
t
N
O
R
M
A
L
Automatic Mode
(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

- 5 -
Manual Mode:
(Automatic Mode – see pg 3)
Your Aprilaire Humidifier Control is installed 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 exam-
ple, 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 and to avoid condensation on your windows. For example, a
wintertime indoor RH of 50% may be considered ideal, but unfortu-
nately, 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 indica-
tion of too high relative humidities. This same condensation can
take place in other areas in your home with the possibility of dam-
age resulting.
As an example, if the outdoor temperature is 20º F, and, following step 3, the
humidifier turns off at “5” on the dial range, then the RH in your home is 35%.
(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

- 6 -
To check the humidifier operation, set the knob to “test”, make
sure that the water saddle valve is open and that there is electricity
to the unit. Generally, the furnace blower motor must be operating
for the Aprilaire Humidifier to function. After the humidifier has oper-
ated for one minute and water is entering the unit and coming out at
the drain, reduce the humidistat setting to the recommended inside
relative humidity, depending on the outside temperature. DO NOT
LEAVE IN TEST MODE AS HUMIDIFIER WILL NOT OPERATE. Follow the
suggested settings prior to a drop in the outside temperature.
MANUAL MODE
(Figure B)
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 you hear the solenoid valve
“click on”. At this point, read the
RH on the dial. This will be very
close to the actual RH in your
home. (See Figure B)
Outside Temperature Recommended RH
+40° 45%
+30° 40%
+20° 35%
+10° 30%
0° 25%
–10° 20%
–20° 15%
(Table 3) Outdoor-Indoor Relative Humidity

- 7 -
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 con-
densation 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 potential 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 softened 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 primarily
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 either
case, the Water Panel evaporator is usually changed once a year. In
the Model 448 Aprilaire Humidifier, 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 recommended with drain type units for increas-
ing capacity and for heat pump applications.
In the drain-equipped models, most of these solids are effectively
controlled by flushing them down the drain.

- 8 -
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.
• Purchase only Genuine Aprilaire Water Panels to maintain
performance.
V. ANNUAL SUMMER SHUTDOWN
1. For Models 448, 558, 568, and 600 close the bypassdamper if
provided. The Model 600 damper is built into the unit and is
easily closed with the small damper handle.
2. Shut off the water supply to the humidifier by closing the sad-
dle valve.
Humidifier Control:
There is no adjustment to the Humidifier Control required for
summer shutdown. (Applies to both Automatic and Manual
Mode.)
VI. PERIODIC PREVENTATIVE MAINTENANCE
NOTE: Periodic inspection and preventive maintenance
of your total heating system is important for efficient and safe opera-
tion. Your heating contractor should include humidifier service at the
same time.
All models are equipped with an in-line water strainer and orifice as
shown below. These parts should be inspected and cleaned periodi-
cally to assure continued proper unit performance.

- 9 -
Inspection and Service Instructions
1. Disconnect electrical power to the
furnace and shut off water supply.
2. Disconnect the water line at the inlet
compression nut.
3. Remove the in-line strainer from inside
the inlet side of the valve 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
compression nut.
7. Remove the orifice from the copper
or plastic 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.
OUTLET
COMPRESSION
NUT
ORIFICE
INLET
INLET
COMPRESSION
NUT
SOLENOID
VALVE
IN-LINE
STRAINER

MODEL 448
MAINTENANCE INSTRUCTIONS
for
APRILAIRE HUMIDIFIER MODEL 448
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 distribu-
tion 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 nec-
essary, 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 9 for reservoir and pump cleaning.
MODEL
448
1. Cover Knob
2. Top Cover
3. Feed Nozzle
4. Distribution Tray
5. Metal Frame
3
4
5
1
2
1
- 10 -

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 humidi-
stat 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:
Humidifier Control: Automatic 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.
- 11 -
MAINTENANCE INSTRUCTIONS
FOR MODELS 448
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

- 12 -
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 Scale Control Insert by twisting and flexing it to
loosen the calcium deposits, or use a putty knife. Inspect the Water Panel
evaporator (Stock No. 10 for Model 558 and Stock No. 35 for Model 568)
and replace with a new Genuine Aprilaire Water Panel if necessary. Slide
the Water Panel back into the Scale Control Insert 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:
Humidifier Control: Automatic 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 Humidifier Control to its original position.
MAINTENANCE INSTRUCTIONS
for
APRILAIRE HUMIDIFIER MODELS 558-568
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
7
56
8
9
1
2
34
MODELS 558-568

- 13 -
1. Note humidistat or control setting and turn dial to the “OFF” position.
2. Turn off water supply.
3. Press the tabs in the latches on the top and bottom of front cover (1) and pull cover off
base with both hands. 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 distribution tray (5) from the evaporative assembly by lifting straight
up from the scale control insert (8). 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 of calcium deposits with a putty knife. Inspect Water Panel evap-
orator (Stock No. 35 for Model 600) and substitute a new Genuine Aprilaire Water Panel
if necessary. Slide the Water Panel back into the scale control insert with the black col-
ored spot up and snap the black distribution 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 pressure and slip it back
onto the drain fitting.
9. Turn on the water supply.
10.
Check system operation:
Humidifier Control: (Automatic or Manual) Check system operation by set-
ting the knob to “Test.” With furnace blower operating and furnace calling
for heat, humidifier will operate for one minute. DO NOT LEAVE IN TEST
MODE AS HUMIDIFIER WILL NOT OPERATE.
11. Set Humidifier Control to its original position.
MAINTENANCE INSTRUCTIONS
for
APRILAIRE HUMIDIFIER MODEL 600
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
Evaporative Assembly
5. Distribution Tray
6. “V” Notches
7. Water Panel
8. Scale Control Insert
9. Drain Hose
10. Integral Damper
MODEL 600

4
5
6
7
8
9
1
2
3
- 14 -
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
Scale Control Insert by twisting and flexing it to loosen the calcium
deposits or use a putty knife. Inspect the Water Panel evaporator (Stock No. 35) and
replace with a new Genuine Aprilaire Water Panel if necessary. 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:
Humidifier Control: (Automatic or Manual) Check system operation by set-
ting the knob to “Test.” With furnace blower operating and furnace calling
for heat, humidifier will operate for one minute.
12. Set Humidifier or control to its original position .
MAINTENANCE INSTRUCTIONS
for
APRILAIRE HUMIDIFIER MODEL 700
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. Water Panel
4. Distribution Tray
5. ”V” Notches
6. Water Panel
7. Scale Control Insert
8. Drain Hose
9. Power Cord
MODEL 700

- 15 -
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 #10005406 Printed in U.S.A.
P.O. BOX 1467 • MADISON, WI 53701-1467
Products For Better Indoor Air Quality™