Zoning Sequence Of Operations; Heating / Cooling Changeover - Lennox iHarmony 10C16 Installation And Setup Manual

Table 23. Smart Hub Parameters
Parameter Description
The maximum airflow CFM is the factory default value for each
particular unit. Depending on each unit's configuration, the default
values may be applied by the gas furnace, the heat pump unit, or
the air handler electric heating value.
The per zone CFM value is the equal division of the number of
zones into the maximum airflow default CFM.
These values will be verified and/or adjusted in the procedure listed
in "Mapping the Design" on page 9.
Specific maximum airflow and per zone CFM is achieved by
selecting the mid-range temperature rise values from the CFM
Zone 1 through 4
Heating CFM tables listed under "Zoning CFM Tables" on page 17, that will
operate <79% IDBP during the test procedures listed under "Testing
the Zones" on page 11 and "Sizing the System" on page 10.
iHarmony minimum CFM listed below will exceed proper
temperature rise operating ranges. Do not use any value less than
the absolute minimum CFM listed in the blower tables regardless of
tonnage value.
The minimum CFM is 250 CFM for 3-ton, 380 for 4-ton or 450 CFM
for 5-ton to the maximum .
Adjustment are in 5 CFM increments.
This parameter setting compensates for a rapid change of the
discharge air temperature due to fast changing conditions. It
examines the change in the discharge air temperature for the
Zoning Anticipated
previous two minutes and extrapolates or looks forward by the
Discharge Air
number of seconds set in the parameter and uses this as the DATS
Temperature
value for staging. This parameter setting helps prevent limit trip/
Adjustment
frozen coil from occurring.
Range is 0 to 120 seconds. Default is 0 seconds. Adjustments are
in increments of 5 seconds.
At the end of a gas cycle, the Heat Blower Off-Delay may not be
long enough to completely cool the heat exchanger. This may result
in a primary limit trip then, or at the beginning of the next heat
demand. This parameter allows the blower to run after a gas heat
Zoning Gas
call ends until the discharge air temperature sensor (DATS) cools to
Heating DAT Cool
Down Target the temperature set in the parameter. If the temperature is set too
low this will cause the temperature in the room to overshoot.
Range is 80 to 90°F (26.67 - 32.22°C). Default is 90°F (32°C).
Adjustments are in increments of 1°F (0.56°C).
In zoning systems, the furnace was upstaging before the discharge
air sensor reached a steady-state value and it would sometimes trip
a limit due to staging up the gas before the blower would even come
on (as occurs during pressure switch calibration).
Zoning Initial The furnace has satisfied the original call for heating and may
Staging Hold Time
still have residual heat in furnace when a second heat demand
for Gas Heating
is called for. This parameter will not allow for the second call of
heating before the delay timer has expired. This parameter allows
an adjustment on top of the initial delay for a heating call. Range is
3.0-8.0 minutes with a default of 5.0 minutes. Can be adjusted in
1-minute increments
Zoning Minimum Range is 90 to 600 seconds. Default is 120 seconds. Adjustments
Zone Run-Time
are in increments of 30 seconds.
Table 23. Smart Hub Parameters
Parameter Description
In cooling mode, this setting sets the discharge air temperature
low limit. Below this temperature, the cooling is turned off. During
cooling testing set the Zoning Supply Air Temp Limit for Cooling low
Zoning Supply
enough (far enough away) so that the outdoor unit does not have
Air Temp Limit
nuisance low pressure switch trips caused by a sudden drop in
for Cooling
supply air temperature as dampers close.
Range is 35 to 45°F (1.67 - 7.22°C). Default is 40°F (4.44°C).
Adjustments are in increments of 1°F (0.56°C).
In heating mode, this setting sets the target discharge air
Zoning Supply Air
temperature.
Temp Limit for Gas /
Range is 120 to 160°F (48.88 to 54.44°C). Default is 125°F (52°C).
Electric Heating
Adjustments are in increments of 5°F (2.78°C).
In cooling mode, this setting sets the target discharge air
temperature.
Zoning Target
Supply Air Temp
Range is 40 to 60°F (4.44 - 15.56°C). Default is 45°F (7.22°C)
for Cooling
plus 7 degrees operating range in all units above this setting.
Adjustments are in increments of 1°F (0.56°C).
In heat pump heating mode, this setting sets the target discharge air
temperature.
Zoning Target
Supply Air Temp
Range is 85 to 110°F (29.44 to 43.33°C). Adjustments are in
for HP Heating
increments of 1°F (0.56°C). Default 90°F (32°C) plus 10 degrees
overshoot for both stage and variable capacity systems.
Range is 100°F to 130°F with 5 degree increment adjustable. In
heating mode, this setting sets the target discharge air temperature.
Zoning Target Supply
Air Temp for Gas/ Default 100°F (38°C) plus 20 degrees (staged units) 10 degrees
Electric Heating
(modulating units) overshoot for both stage and variable capacity
systems.

Zoning Sequence of Operations

When power is first applied, the green Status LED will flash, indicating that the
damper control is functioning normally. When the control is first powered on,
there is a 5 minute minimum time delay during which only the fan output will
respond.

Heating / Cooling Changeover

The following is an example of how the system operates during a heating
/ cooling changeover. When the system is satisfying a call from zone 1 for
heating and receives a call for cooling from zone 2, the following will occur:
• Then system will continue to fulfill the demand from zone 1 until satisfied, or
a maximum time of 20 minutes has occurred.
• If after 20 minutes the system is still operating based on satisfying the heating
demand from zone 1, the system will terminate that demand.
• The system will then shut system down for five (5) minutes. This will allow for
system temperatures and operating pressures to stabilize.
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