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–20°F. –29°C. 15% +10°F. –12°C. 30%
–10°F. –23°C. 20% +20°F. – 7°C. 35%
0°F. –18°C. 25% Above 20° –7°C. 40%
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Principle of Operation
Your White-Rodgers Humidifier uses the same method of evaporation you observe in
nature after a summer shower. Mother Nature’s technique is simple: warm air passes
over a thin layer of water spread over a large area, causing the water to evaporate
and raising the level of humidity. Your humidifier creates the same natural response
with an evaporator pad that dispenses water evenly in front of a warm air stream.
You’ll notice that the evaporator pad has many holes and connecting strands. These
significantly increase the surface from which water can evaporate. This warm air
evaporative process, is intensified by the warm air from your furnace, this is what
makes your humidifier perform efficiently.
The system is controlled by a humidistat that monitors the relative humidity in your
home, and activates or deactivates the humidifier accordingly. Water evaporated from
the humidifier leaves behind all its impurities (e.g., calcium, iron, lime, bacteria, etc.),
thus creating a purified vapor that doesn’t pollute your indoor air. As a result, your
home will be free from these contaminants… and your family will almost certainly
be healthier and more comfortable.
How Your Humidifier Works. . .
Model HFT2100 & HFT2700. When your home’s air is dryer than the selected
level of humidity, the humidistat activates the low-voltage solenoid in your humidi-
fier, allowing water to flow across the unit’s media. Warm, dry air is then forced
through the humidifier cabinet by the furnace blower. As the warm air evaporates
the water, the resulting moist (or humidified) air is circulated throughout your home
by the heating system.
Model HFT2900FP. (White-Rodgers Model HFT2900FP operates identically to
Model HFT2100 & HFT2700, except that warm air is forced through the humidifi-
er cabinet by a humidifier fan rather than by the furnace blower.)
Operating Instructions
Your new humidifier is controlled by a humidistat that is installed either on the cold
air return of your furnace, or on an interior wall of your home. The recommended
settings for this control may seem illogical until you understand the principle behind
them....
As you can see from the Humidistat Settings chart below, the recommended setting
goes down as the outside temperature decreases—just the opposite of how
your furnace’s thermostat operates. To understand the reason for this, think of what
happens to an ice-cold drink when it’s outside on a hot summer day… water
(or condensation) forms on the outside of the glass. Condensation occurs because
the hot summer air contains humidity, and the cold surface of the glass cools the
surrounding air. Once cooled, the air molecules become smaller and can no longer
hold as much moisture. The result is that water droplets accumulate on the glass.
The same principle applies to your home during the winter, when the outside
temperature drops and the inside air remains warm and humid. In order to retain
moisture in your home and prevent condensation, it’s necessary to turn your
humidistat down as outside temperatures fall.
About Your White-Rodgers Humidifier
Checking the Humidifier for Proper Operation
To check your humidifier for proper operation after servicing or winter start-up,
follow these procedures:
1. Turn the furnace blower to the OFF position, making sure the solenoid valve
is closed.
2. Turn the furnace blower ON and set the humidistat to the full on position. The
solenoid valve should open.
3. Make sure the water flow from the solenoid falls directly into the distribution
tray. (The solenoid valve should limit the flow to approximately four gallons per
hour at a line pressure of 60 P.S.I.)
4. To avoid overflow, run the humidifier long enough to be sure the drain tubing is
carrying water to the waste line.
WARNING: DO NOT SET HUMIDITY CONTROL TOO HIGH. Use the
recommended settings shown on humidistat nameplate.
Recommended Humidistat Settings
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