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- GENERAL MAINTENANCE FOR ALL MODELS
of Water Characteristics
MAINTENANCE INSTRUCTIONS FOR SPECIFIC MODELS
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.
|WARNING! 120 volts may cause injury from electrical
shock. Disconnect power and shut off water supply before
CAUTION! Sudden operation may cause personal injury
or property damage. Turn humidistat or Auto-TracTM
Control System, to "off" or lowest setting
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. Since Research Products does not sell service parts and/or
Water Panel® evaporators direct, please
proceed as shown in the maintenance section.
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 equipment 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.
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With your purchase of a humidification system, you have invested in an
automatic humidifier that operates on the evaporative principle -
nature's own way of adding moisture - and will provide the proper
relative humidity (see operating instructions) 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 maximum 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 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 maximum) 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 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 accessible or
available. For these situations, or where high water hardness is not a
problem, a specially designed Aprilaire Humidifier, Model 445, is
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
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 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 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 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, the design, the performance incorporated into your Aprilaire
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Auto-Trac Control System: (Manual
Your Auto-Trac control System is installed in the cold air return.
During the first heating season, your Auto-TracTM
Control System needs to be set initially to match your home's condition.
Please follow these steps when adjusting your Auto-Trac (refer to Figure
(Table 1) Operation Guide
- 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).
- 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
|Condensation on windows
||Reduce the setting on Auto-Trac dial
by 1 increment.
|Lack of humidity
||Increase setting on Auto-Trac dial by
|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.
||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.
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 settings in the event you temporarily
move the knob when performing annual maintenance of the Aprilaire
Your Aprilaire Humidifier, controlled by the Auto-Trac Control
System, is a high precision system that will accurately maintain the
relative humidity in your home. For every 1° change in outdoor
temperature, the Auto-Trac will automatically adjust the indoor relative
humidity by 1/2% (RH). If you would like to determine the relative
humidity in your home, follow these steps:
As an example, if the outdoor temperature is 20°F, and,
following step 3, the humidifier turns off at "5" on the dial
range, then the relative humidity in your home is 35%.
- Determine the outdoor temperature.
- Activate the furnace blower by setting your thermostat fan switch
to the "On" position, or setting your thermostat to a
- Turn the Auto-Trac 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.
- 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
- Return the thermostat and Auto-Trac to their original settings.
The Auto-Trac 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 relative humidity.
Manual Humidistat: (Auto-Trac
Your new Aprilaire Humidifier is controlled by an accurate 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
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 relative humidity
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 relative humidity of 50% may be considered ideal, but
unfortunately, it probably would result in damage to your home.
Observance of the recommended relative humidity 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
(Table 3) Outdoor-indoor Relative Humidity
The humidistat is a precision instrument that can be used to
determine the relative humidity 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 relative humidity on the dial. This will be very close to the actual
relative humidity in your home.
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 recommended inside relative humidity, depending on the outside
temperature. Follow the suggested settings prior to a drop in the
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 potential damaging excess moisture levels.
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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 445
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 increasing capacity
and for heat pump applications.
In the drain-equipped models, most of these solids are effectively
controlled by flushing them down the drain.
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For best performance, we recommend that you replace the water panel
evaporator in your Aprilaire Humidifier annually. Use only genuine
Aprilaire Stock No. 10, 12, or 35 replacement water panels.
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For the models 220, 224, 440,445A, 445, 550A, 550, 560A and 560, close
the bypass damper if provided. For the models 445A and 445, empty the
Auto-Trac Control System:
Humidifiers controlled by the Auto-Trac Control System require no
control adjustment. Shut off the water supply to the humidifier by
closing the saddle valve.
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.
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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. 445A 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 continued proper unit
|Inspection and Service Instructions
- Disconnect electrical power to the furnace and
shut off water supply.
- Disconnect the water line at the inlet compression
- Remove the in-line strainer from inside the inlet
fitting by using a small nail or wire.
- Flush the in-line strainer clean or replace with a
new strainer, Service Department, Part No. 4004.
- Replace the in-line strainer and reconnect the
inlet water line (Double Wrench To Prevent
- Disconnect the water line at the outlet
- Remove the orifice from the copper or plastic tube
and make sure this small opening is unplugged.
- Replace the orifice and reconnect the outlet water
line (Double Wrench To Prevent Leaking).
- Turn on water supply and reconnect electrical
power to the furnace.
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Your Research Products Corporation Aprilaire®
Humidifier unit is expressly warranted for one (1) year from date of
installation 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
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
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 WARRANTIES 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 incidental 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.
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© RESEARCH PRODUCTS CORPORATION 1998