Lennox Harmony III Installation Instructions Manual page 10

3. Determine heating PIAB and total heating air CFM
delivered during a heating call Calculate these to-
tals using the formulas and example in Table 7. The ex-
ample uses the following assumptions:
Zone 1 Jumper
D
Zone 2 Jumper
D
D Zone 3 Jumper
Zone 4 Jumper
D
Zones calling for heat
D
D Heat reduction jumper
Maximum CFM
D
Minimum CFM
D
Table 7
Determine Total Heating CFM Delivered
Formulas:
Total PIAB =
(Sum of Calling Zones
Jumper Positions)
Heating PIAB =
Total PIAB x (1 − Heating air reduction setting)
Total Heating CFM =
Heating PIAB x (CFM Max − Min) +
1st− Find Total PIAB:
[Jumpers 30% +0% +40% +0%]
+ [2 zones −1]/3 . . . . . . . . . . . . . . . . . . . .
TOTAL . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Blower cannot support 103%; uses 100%
2nd− Find Heating PIAB:
[Total PIAB] . . . . . . . . . . . . . . . . . . . . . . .
x [1−Heating air reduction setting]
TOTAL . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3rd− Find Heating Total CFM:
[Heating PIAB] . . . . . . . . . . . . . . . . . . . . .
x [CFM (Max) 2220 − (Min) 720]
+ [Min CFM] . . . . . . . . . . . . . . . . . . . . . . .
TOTAL . . . . . . . . . . . . . . . . . . . . . . . . . . . .
505023M 04/06
30%
50%
40%
OFF
1 & 3
20
2220
720
(# of Zones Calling − 1)
+
3
(Min CFM)
. . . . . . .30 +.00 +.40 +.00
+. 33
1.03
. . . = 1
b
1
. . . . . x 1−.2
= .8
b
.8
. . . . . . . x 1500
+ 720
= 1920 CFM
4. Determine total air delivered during a continuous
blower call Calculate these totals using the formu-
las and example (Table 8) which uses the same as-
sumptions as table 7, except with zones 1, 2 and 3 call-
ing for cooling, and with 25% air reduction:
Determine Total Continuous CFM Delivered
Formulas:
Total PIAB =
(Sum of Calling Zones
Jumper Positions)
Continuous Air PIAB =
Total PIAB x (1 − Cont. air reduction setting)
Total Continuous CFM =
Cont. Air PIAB x (CFM Max −
Min)
1st− Find Total PIAB:
[Jumpers 30% +50% +40% +0%]
+ [3 zones −1]/3 . . . . . . . . . . . . . . . . . . . .
TOTAL . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Blower cannot support 186%; uses 100%
2nd− Find Continuous Air PIAB:
[Total PIAB] . . . . . . . . . . . . . . . . . . . . . . .
x [1−Continuous air reduction setting]
TOTAL . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3nd− Find Total Continuous CFM:
[Continuous Air PIAB]
x [CFM (Max) 2220 − (Min) 720]
+ [Min CFM] . . . . . . . . . . . . . . . . . . . . . . .
TOTAL . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IMPORTANT
If any changes are made to the blower speed selec-
tions on the SureLight
control PIAB calculations must be performed again
to ensure proper airflow.
Page 10
Table 8
(# of Zones Calling − 1)
+
3
+ (Min CFM)
. . . . . .30 +.50 +.40 +.00
+. 66
1.86
. . . = 1
b
1
. . 1−.25
= .75
b
. . . . . . . . . . . . . . .75
. . . . . . . x 1500
+ 720
= 1845 CFM
®
or BDC3 boards, the zone