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505232 06/07

Page 10

Humiditrol

Accessory

If a Humiditrol

accessory is present in the equipment at hand, then the

SignatureStatt thermostat must be configured to properly operate the Hu-

miditrol

accessory as follows (see Figure 6 for the Humiditrol operation

flowchart):

1. From the Home screen, press MENU. Then select INSTALLER SET-

TINGS. Select HUMIDITROL, then select ENABLE. Verify that the

HUMIDITROL ON is displayed in the INSTALLER SETTINGS menu.

2. Select MAIN MENU. Then select DEHUMIDIFY. Select MODE, then

select HUMIDITROL. The SignatureStatt thermostat is now config-

ured to operate the Humiditrol

accessory.

NOTE − Humiditrol

operation requires use of an outdoor sensor. If sensor

is not connected and Humiditrol

is enabled, OUTSIDE ERR" is displayed

on the main screen.

SignatureStatt thermostat operation with Humiditrol

enabled

Cooling onlyDehumidification will only occur if a dehumidification de-

mand is present, a cooling demand is not present, outdoor temperature is

less than 95ºF, and the indoor temperature is not cooler than:

Heating setpoint + 2ºF (IF the difference between cooling and heating

setpoints is greater than the deadband)

Cooling setpoint – deadband + 2ºF (IF the difference between cooling

and heating setpoints is less than the deadband)

In this case, the 24 VAC is removed from the D" terminal and the Y2" ter-

minal (if available) becomes activated with 24VAC. This will cycle the in-

door variable speed motor to the dehumidification speed and cycle Y2 On"

to the outdoor unit Cooling calls have priority over Humiditrol

calls.

Heating onlyThermostat will cycle heating On" and Off  to maintain

heating setpoint. Dehumidification functions are disabled.

Calculating maximum allowable overcooling in cooling-only

mode START

Maximum allowable over-

cooling is equal to the

cooling setpoint minus

the deadband plus 2ºF

Is the

cooling setpoint

minus

heating setpoint

greater than the

deadband

YES

Maximum allowable over-

cooling is equal to the

heating setpoint plus 2ºF

Values below were calculated

following this flow diagram

"2" in calculations below is for over-

cool," up to 2°F above heating setpoint.

Heating

Only Set-

point

Cooling

Only Set-

point

Deadband Set-

ting (Range 3

to 8°F)

Maximum Allowable Overcool-

ing:

75 °F 75 °F 4 °F 75 – 4 + 2 = 73°F (difference is

less than deadband setting)

80 °F 77 °F 5 °F 77 – 5 + 2 = 74°F (difference is

less than deadband setting)

74 °F 79 °F 6 °F 79 – 6 + 2 = 75°F (difference is

less than deadband setting)

70 °F 79 °F 6 °F 70 + 2 = 72°F (79 –70 = 9 > 6

therefore use heating setpoint)

AutochangeoverDehumidification will only occur if a dehumidification

demand is present, a cooling demand is not present, outdoor temperature

is less than 95°F, and the indoor temperature is not cooler than 2ºF above

heating setpoint.

In this case, the 24 VAC is removed from the D" terminal and the Y2" termi-

nal (if available) becomes activated with 24VAC. This will cycle the indoor

variable speed motor to the dehumidification speed and cycle Y2 On" to

the outdoor unit. Cooling calls have priority over Humiditrol

calls. Humidi-

trol® mode is allowed to overcool up to 2°F above the heating setpoint.

Note: If the last thermostat demand was a heating demand, the thermostat

does not require a cooling demand before Humiditrol

operation.

Brand	Lennox
Model	SignatureStat 81M26
Category	Thermostat
Language	English

Lennox SignatureStat 81M26 User Manual

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Questions and Answers:

Lennox SignatureStat 81M26 Specifications

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