Page 21
On-Board Links
Note:
In communicating systems with a conventional out
door unit (non-communicating), the on-board clippable
links must be set to properly configure the system.
WARNING
Carefully review all configuration information pro
vided. Failure to properly set DIP switches, jumpers
and on-board links can result in improper operation!
On-Board Link W914 Dehum or Harmony (R to DS)
On-board link W914, is a clippable connection between ter
minals R and DS on the integrated control. W914 must be
cut when the furnace is installed with either the Harmony
III
t
zone control or a thermostat which features humidity
control. If the link is left intact the PMW signal from the Har
mony III control will be blocked and also lead to control
damage. Refer to table 12 for operation sequence in ap
plications including SL280UHNV, a thermostat which fea
tures humidity control and a single-speed outdoor unit.
Table 13 gives the operation sequence in applications with
a two-speed outdoor unit.
On-Board Link W951 Heat Pump (R to O)
On-board link W951 is a clippable connection between ter
minals R and O on the integrated control. W951 must be cut
when the furnace is installed in applications which include a
heat pump unit and a thermostat which features dual fuel
use. If the link is left intact, terminal “O” will remain ener
gized eliminating the HEAT MODE in the heat pump.
On-Board Link W915 2 Stage Compr (Y1 to Y2)
On-board link W915 is a clippable connection between ter
minals Y1 and Y2 on the integrated control. W915 must be
cut if two-stage cooling will be used. If the Y1 to Y2 link is
not cut the outdoor unit will operate in second-stage cool
ing only.
TABLE 12
OPERATING SEQUENCE
SL280UHNV, Non-Communicating Thermostat with Humidity Control Feature and Single-Speed Outdoor Unit
OPERATING
SEQUENCE
SYSTEM DEMAND
SYSTEM RESPONSE
System
Condition
Step
Thermostat Demand
Relative Humidity
Compres
sor
Blower
CFM
(COOL)
Comments
Y1
O
G
W
1
Status
D
NO CALL FOR DEHUMIDIFICATION
Normal Operation
1
On
On
On
Acceptable
24
VAC
High
100%
Compressor and indoor
blower follow thermostat
demand
BASIC MODE (only active on a Y1 thermostat demand)
Normal Operation
1
On
On
On
Acceptable
24
VAC
High
100%
ComfortSense
®
7500
thermostat energizes Y1
and de-energizes D on a
call for de-humidification
Dehumidification
Call
2
On
On
On
Demand
0
VAC
High
70%*
PRECISION MODE (operates independent of a Y1 thermostat demand)
Normal Operation
1
On
On
On
Acceptable
24
VAC
High
100%
Dehumidification mode
begins when humidity is
greater than set point
Dehumidification
call
2
On
On
On
Demand
0
VAC
High
70%*
Dehumidification
call ONLY
1
On
On
On
Demand
0
VAC
High
70%*
ComfortSense
®
7500
thermostat
will try to
maintain room humidity
setpoint by allowing the
room space to maintain a
cooler room thermostat
setpoint**
Jumpers at indoor unit with a single stage outdoor unit.
With Condensing unit - Cut W914 (R to DS) on SureLight
®
control.
With Heat Pump - Cut W914 (R to DS) & W951 (R to O) on SureLight
®
control
Use Dave Lennox ComfortSense
®
7500 thermostat Y2081 4 heat / 2 cool for this application
*Dehumidification blower speed is 70% of COOL speed for all units .
**In Precision mode, ComfortSense
®
7000 thermostat will maintain room temperature up to 2 °F (1.2°C) cooler than room setting.
