Lennox SIGNATURE SLP99DF070V36, Installation Instructions Manual

Page 34

7 -   One line voltage “EAC” 1/4” spade terminal is 

provided on the furnace integrated control. Any 

electronic air cleaner rated up to one amp can be 

connected to this terminal with the neutral leg of 

the circuit being connected to one of the provided 

neutral terminals. See FIGURE 50 for location of 

terminal. This terminal is energized when the indoor 

blower is operating.

8 -   One line voltage “HUM” 1/4” spade terminal is 

provided on the furnace integrated control. Any 

humidifier rated up to one amp can be connected to 

this terminal with the neutral leg of the circuit being 

connected to one of the provided neutral terminals. 

See FIGURE 50 for location of terminal. This 

terminal is energized in the heating mode when the 

indoor blower is is operating.

9 -   One 24V “H” terminal is provided on the furnace 

integrated  control  terminal  block.  Any  humidifier 

rated up to 0.5 amp can be connected to this 

terminal with the ground leg of the circuit being 

connected to either ground or the “C” terminal. See 

FIGURE 50 for location of terminal.

10 -  

Install the room thermostat according to the 

instructions provided with the thermostat. See 

TABLE 15 for thermostat connections. If the furnace 

is being matched with a heat pump, refer to the 

instruction packaged with the dual fuel thermostat.

NOTE - 

The discharge air temperature sensor is intended 

to be mounted downstream of the heat exchanger and air 

conditioning coil. It must be placed in free airflow, where 

other accessories (humidifiers, UV lights etc.) will not in

-

terfere with its accuracy. Wiring distance between the fur

-

nace and discharge air sensor should not exceed 10 ft. 

when wired with 18-gauge thermostat wire.

TABLE 13

Run Length — Non Communicating

Wire Run Length

AWG#

Insulation/Core Types

Less than 100’ (30m)

18

Color-coded, temperature 

rating 95ºF (35ºC) 

minimum, solid core. (Class 

II rated wiring)

More than 100’ (30m)

16

TABLE 14

Run Length — Communicating

Wire Run Length

AWG#

Insulation/Core Types

Maximum length 

of wiring for all 

connections on the 

RSBus is limited 

to 1500 feet (457 

meters).

18

Color-coded, temperature 

rating 95ºF (35ºC) 

minimum, solid core. (Class 

II rated wiring)

Thermostat Selection

The SLP99DFV is designed to operate in a variable 

rate capacity mode using a two-stage thermostat. The 

SLP99DFV will automatically adjust firing rate based upon 

thermostat cycle times.
A communicating thermostat must be used in communi-

cating applications. Refer to the instructions provided with 

the thermostat for installation, set-up and operation
For optimal performance in non-communicating applica-

tions, Lennox recommends use of a ComfortSense® 7500
high quality electronic digital thermostat or any other with 

adjustable settings for 1st stage / 2nd stage on / off differ

-

entials and adjustable stage timers.
Lennox recommends the following two-stage thermostat 

set-up for optimal variable rate capacity mode: First heat 

stage  differential  set  to  1/2  to  1  degree  F;  second  heat 

stage  differential  set  to  1/2  or  1  degree  F;  second  heat 

stage upstage timer disabled, or set to maximum (1 hr 

minimum).

Indoor Blower Speeds

NOTE - When the SLP99DFV is used with a commincat-

ing thermostat, proper indoor blower speed selections are 

made by the thermostat.

1 -   When the thermostat is set to “FAN ON,” the indoor 

blower will run continuously at a percentage of 

the second- stage cooling speed when there is 

no cooling or heating demand. The percentage is 

set using DIP switches 6 and 7. See TABLE 23 for 

allowable circulatuion speeds.

2 -   When the SLP99DFV is running in the heating 

mode, the integrated control will automatically 

adjust the blower speed to match the furnace firing 

rate. This speed can be adjusted up or down by 

7.5% or 15% using DIP switches 14 through 16 for 

the low heat speed and 17 through 19 for the high 

heat speed. See TABLE 23 for allowable heating 

speeds.

3 -   When there is a cooling demand, the indoor blower 

will run on the cooling speed designated by the 

positions of DIP switches 8 through 11.

Generator Use - Voltage Requirements

The following requirements must be kept in mind when 

specifying a generator for use with this equipment:

•   The furnace requires 120 volts + 10% (Range: 108 

volts to 132 volts).

• 

 The furnace operates at 60 Hz + 5% (Range: 57 Hz 

to 63 Hz).

•   The furnace integrated control requires both po-

larity and proper ground. Both polarity and proper 

grounding should be checked before attempting to 

operate the furnace on either permanent or tempo-

rary power.

•   Generator should have a wave form distortion of 

less than 5% THD (total harmonic distortion).