Testing The Zones - Lennox iHarmony 10C16 Installation And Setup Manual

- Verify IDBP <79% and record value.
- Verify DAT has approached cooling target temp setting without
exceeding it during 100% cooling rate.
◊ If not, return to equipment and lower high cooling airflow CFM
to achieve maximum cooling capacity at a lower discharge air
temperature
◊ The DAT should be approximately 2° above the setting to allow
for air filter loading
- If any heating or cooling test results in IDBP >79% return to the
dealer control center. A higher IDBP >79% is an indication of a high
static duct system or loaded filter.
- Select > equipment.
◊ Select furnace and lower the high heating airflow CFM accord-
ing to the amount assumed needed and retest until IDBP value
is confirmed <79%.
◊ Select the associated outdoor unit and lower the high cooling
and/or heat pump heating airflow to match the heating CFM val-
ue.
- Equipment maximum capacity is now properly sized to the duct
system.
- Return to thermostat's home screen.

Testing the Zones

Verify proper operation of each or combination of zones.
• Heating test per zone.
From the thermostat's home screen, navigate to the smallest zone.
»
» Select modes and schedules and select heat only.
Initiate a 5° heating call and wait for "heating" status on the display
»
Then navigate to settings> advanced settings > dealer control
-
center > diagnostics > select all > start diagnostics.
Select Furnace
-
◊ Verify heating rate = 70% typical starting rate
◊ For modulating furnace:
> Heating rate will change to the approximate percentage val-
ue of CFM per zone divided by max airflow setting.
> If discharge air temperature (DAT) is less than target air
temp the gas valve will increase in 5% increments until tar-
get air temp is achieved.
> If increased gas valve rate exceeds the overshoot operating
temp range the gas valve will decrease by 5% increments
until the thermal balance point is established in the ade-
quate air range of the zoning map.
◊ For staged units:
> Heating rate will remain at 70% unless DATS does not re-
port advancement of the DAT quickly enough (approximate-
ly 180 seconds) then second-stage will initiate at that time.
> Second stage will drop out at overshoot operating temp
range.
> The DAT will seek a thermal balance point based on the
ratio of minimum CFM to minimum capacity BTU above the
overshoot temp.
◊ Verify CFM demand is the value selected in setup.
> The 50% cutback values are related to wiring terminal
points, dirty voltage, and excessive IDBP >79%.
> Once a 50% cutback mode is learned by the ECM due to
excessive IDBP it will always begin at 50% cutback.
> This mode is often associated with the alert code E250.
> Alert code E250 will occur on every heating call due to inad-
equate air as the zoning map indicates.
> Various small percentage cutbacks are most often associat-
ed with thermostat wires connected on the damper control
module and not on the indoor unit control's terminals.
◊ The indoor blower power is helpful in determining if the zone
ductwork has a high static pressure that the blower may not be
able to overcome and cause the blower to run in cut back mode.
> Verify Indoor Blower Power is <79%.
+ Lower velocity range is 1% - 30%.
These have a quiet operation but may require duct bal-
ancing for uniform room distribution.
+ Moderate velocity range is 30% - 65%.
These have more noticeable operation but may help
overcome path of least resistance duct design.
+ High velocity range is 65% - 79%.
These are very noticeable but an alternative to remod-
eling the duct system without experiencing blower cut-
back alert codes E291, E311 and E312.
+ Excessive velocity range is 79%-83%.
These are not recommended due to unwanted veloc-
ity and possible blower fluctuation with cutback mode
operation. Occasional success may sometimes occur
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