Page 59
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 congure the system.
WARNING
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 Dehum or Harmony (R to DS) On-
board link W914, is a clippable connection between termi-
nals R and DS on the integrated control. W914 must be
cut when the furnace is installed with either the Harmony
III zone control or a thermostat which features humidity
control. If the link is left intact the PMW signal from the
Harmony III control will be blocked and also lead to control
damage
Refer to TABLE 17 for operation sequence in applications
including EL297UHV, a thermostat which features hu-
midity control and a single-speed outdoor unit. TABLE 18
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
terminals 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 re-
main energized 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
terminals 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
cooling only.
TABLE 17
OPERATING SEQUENCE
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
Compre
ssor
Blower
CFM
(cool)
Comments
Y1 O G W1 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-
call
2 On On On Demand 0 VAC High 70%
PRECISION MODE (operates independent of a Y1 demand)
Normal Operation 1 On On On Acceptable
24
VAC
High 100%
mode begins when
humidity is greater
than set point
Call
2 On On On Demand 0 VAC High 70%
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
Dave Lennox ComfortSense® 7000 thermostat to use for this application - Y2081 4 heat / 2 cool
*Dehumidication 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.
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