Heat Pump, Dual-Fuel, Dual-Fuel Tempering And Balance Points; Balance Points - Heat Pump; Low Balance Point; High Balance Point - Lennox iComfort Wi-Fi Setup Manual

Heat Pump, Dual-Fuel, Dual-Fuel Tempering and Balance Points

IMPORTANT - The Balance Points feature requires that a
sensed outdoor temperature is provided to the thermostat. This
can be either a connection to Wi-Fi (for local temperature
information) or a connection to an outdoor sensor (included in all
communicating iComfort
temperature sensor X2658 for non-communicating heat pumps).

BALANCE POINTS - HEAT PUMP

The LOW and HIGH set points may be controlled by
®
theiComfort Wi-Fi thermostat using the LOW and HIGH
Balance Points feature. To enable the Balance Points feature,
go to the installer section equipment button. Scroll down to the
System screen, select edit and scroll down to Balance Points
Controls. Use arrows to select Enabled and then press save.
See figure 42 for a simplified explanation of how balance
points control system operation.

LOW BALANCE POINT

If the outside temperature is below the programmed low balance
point (set by default at 25°F), compressor operation is not
allowed. Since the heat pump is not as effective at a lower
outdoor temperatures, it may be more comfortable to use the
auxiliary electric heat or the furnace (in dual fuel systems, it may
be more economical) to satisfy a demand for heat. The low
balance point options are from -20°F to the high balance point
temperature. The set point can be adjusted in 1.0°F steps.

HIGH BALANCE POINT

If the outside temperature is above the programmed high
balance point (set by default at 50°F), auxiliary electric heat
operation or furnace operation (in dual fuel system) is not
allowed. This ensures that the lower cost heat pump operation
will satisfy the heating demand, rather that the more expensive
auxiliary electric heat. The high and low balance points will not
lock out both compressor heat and auxiliary heat/furnace at the
same time.
507343-01
®
heat pumps; optional outdoor
DUAL-FUEL APPLICATIONS
The following information is applicable to communicating
systems only.
1. Staged Operations
Dual-fuel applications, which include both a Heat Pump
(XP17 or XP21 only) and a gas furnace, will provide
multiple stages of heating. For example, a two-stage heat
pump would deliver two stages of heat. The gas furnace
can add two to four more stages of heat. Figure 42 flow
chart illustrates Dual Fuel operation with Balance Points.
2. Variable Capacity (Modulating) Operations
Dual-fuel applications, which include both a variable
capacity heat pump (XP25) and a variable capacity gas
furnace (SLP98), will provide variable capacity heating.
3. Tempering — Staged Furnace
Dual-fuel tempering staged furnace employs no sensor
implementation. Furnace cycles on and off at first stage
rate.
• First cycle on-time is longer than subsequent times to
bring temperature up.
• Subsequent
temperature.
4. Tempering —
Furnace (SLP98)
Dual-fuel tempering staged furnace employs no sensor
implementation. Furnace starts heating at minimum heat
rate while defrost is active.
• Testing has shown the entering air is within
acceptable limits.
• During defrost the airflow will run at second-stage
CFM.
Page 36
times are shorter
Variable Capacity (Modulating)
to maintain