Humidification - Lennox L7742U Programming And Application Manual

Humidification

INSTALLER SETTINGS
Humidification (adding moisture to air) is provided only when the ther-
mostat is in heat mode. The humidification signal (H terminal) to the hu-
midifier (off when the thermostat is in the COOL mode) controls humidi-
fication. When the thermostat is powered, the H terminal is normally
inactive (open circuit) in any mode (HEAT, COOL, OFF). When a hu-
midification demand is present, H terminal and G terminal are ener-
gized (24V).
HUMIDITY SETTING default OFF. Installer settings must be
turned on before the user will have control over the humidity. The
mode selected determines how the user can adjust the relative humid-
ity (RH). The installer settings include BASIC, PRECISION, DEW-
POINT, and OFF.
BASIC & PRECISION these thermostat modes allow the user to con-
trol the relative humidity (RH) between 15 and 45%. The following con-
ditions must be met for either mode to operate:
S
humidification mode has been enabled, and
S
the unit is in HEAT mode, and
S
humidification demand exists (24V present at H), and
Additionally, the BASIC mode requires:
S
heat demand exists (W energized [for gas heat, W may be ener-
gized with G de−energized]).
Scroll to HUMIDITY SETTINGS; press ENTER. Press the box below
HUMIDIFY.
HUMIDITY SETTINGS
HUMIDIFY DEHUMIDIFY
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Use up/down arrows to select BASIC or PRECISION; press ENTER.
HUM MODE SETTING
DEF(OFF) PRECISION
Default setting is 45% RH. Use up/down arrows to define what NEW
SETPOINT IS (between 15 to 45%); then press SAVE.
HUM SETPOINT
DEFAULT (45%)
DEWPOINT Dewpoint adjustment mode will change the humidifica-
tion setpoint based on the outdoor temperature and a user−defined dew
point adjustment setting.
NOTE − In dew point adjustment mode, the humidification setpoint has
no effect whatsoever on unit operation. Only the user−defined dew point
adjustment setting affects operation per the following formula:
Outdoor Temp (ºF)
RH =
setpoint
RH
Where:
user dew point adjustment
RH
setpoint
Scroll to HUMIDITY SETTINGS; press ENTER.
HUMIDITY SETTINGS
HUMIDIFY DEHUMIDIFY
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Press the box below HUMIDIFY. Use up/down arrows to select DEW-
POINT; press ENTER.
HUM MODE SETTING
DEF(OFF) DEWPOINT
Use up/down arrows to select NEW DEWPOINT ADJ setpoint (be-
tween +15 to −15%); then press SAVE.
DEW POINT ADJ
DEFAULT (O%)
NOTE − Dewpoint adj available only when outdoor sensor is attached.
Page 18
4O%
RH
user dew point adjust -
+ 25 +
2
cannot exceed +/−15% and
minimum is 15% and cannot exceed 45%.
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−5%
ment