Lennox Harmony III Installation Instructions

TROUBLESHOOTING
Page 58
505023M 08/11
Troubleshooting Air Delivered By Blower
The actual CFM delivered to each zone will be determined
by the zone control system settings, blower motor control
board settings, zone thermostat demand status (calling for
heating, cooling, continuous fan, or no demand [zone
damper closed]), and the air distribution system’s duct
size.
When the zone control system is set for a particular zone,
heating reduction jumper, and/or continuous air reduction
settings determine the total CFM available from the unit as
follows:
1. Determine Total Unit PIABUsing the formula in
Table 11, calculate the Total Percent into Adjustment
Band. This illustrates the percentage into the adjust-
ment band that the motor runs when more than one
zone is calling for conditioning.
2. Determine Total CFM DeliveredContinuing from
the previous example and assumptions, and using the
formula in Table 11, calculate the total CFM delivered.
The max. and min. CFM values used in the formula
should correspond to the jumper settings on the blow-
er control board. This value represents the volume of
air received if all zones were calling for cooling.
3. Determine heating PIAB and total heating air CFM
delivered during a heating callCalculate these to-
tals using the formulas and examples in Table 12.
4. Check "CFM" LED or 7−Segment LED on indoor unit
to obtain approximately CFM the indoor unit is operat-
ing at.
5. Determine total air delivered during a continuous
blower callCalculate these totals using the formu-
las and examples in Table 13.
Table 11. Determine total PIAB & total CFM delivered
Example values
Jumpers CFM
Zn1 Zn2 Zn3 Zn4
Cont. Air
Reduction
Heating
Air Red.
Min. Max.
30% 10% 20% OFF 25% 20% 720 2200
Gray zones are calling.
Total PIAB Formula
(# of zones calling − 1)
3
(Sum of calling zones 1 to 4
jumper positions)
+
1. Using example values above, find Total PIAB:
Jumper positions .10 +.20 .30. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(# of Calling zones minus 1) divided by 3 (2−1)/3 +.33. . . . . . . . . .
Total (motor runs 63% into adjustment band of motor) . 63. . . . . .
Total CFM Formula
Total PIAB x (CFM max. − CFM min.) + (min. CFM)
2. Then find Total CFM:
Total PIAB from step 1. .63. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CFM max. − CFM min. (2220−720) x1500. . . . . . . . . . . . . . . . . . . . . .
CFM into adjustment band 945. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Total CFM (CFM min + CFM into adjustment band) 1665. . . . . . . .
IMPORTANT
If any blower speed settings (furnace or air handler)
are changed, the zone control PIAB calculations
must be performed again to ensure proper airflow.

Lennox Harmony III Specifications

General

Brand	Lennox
Model	Harmony III
Category	Control Systems
Language	English