11
Zone Weight Calculation
A H Threshold Set-Point
Stage-up occurs when:
100%
All 4 Zones call together
80%
Zones 1, 2 & 4 call together
70%
Any 3 Zones call together
55%
Zone 2 with either 1 or 4 call together
Zone weight settings should provide maximum airflow to zones calling, without creating objectionable air noise
at the registers. Since many systems serve a single zone the majority of the time, low stage energy savings
will be achieved.
Y2 (High Stage) blower and W2 (High Stage) FF Furnace capacity will be engaged any time the
accumulated, served zone weight is equal to or greater than the AH Threshold setting in the Set-
Up Wizard.
Alternate “AH Threshold” setting for the above example:
The following is an example of “Zone Weight” and “Air Handler Threshold” set-up to demonstrate the functionality
behind the settings you choose.
The application below is a two story home being served by four independent zones. The zone
weights are determined by simply dividing the number of runs in each zone by the total number of
runs in the system.
Total zone weight does not need to add up to 100%
and may, in fact, be over
or under weighted to produce the desired results.
Zone 1
Living area, 1st Fl
(5-6” runs/20 = 25%)
Zone 2
Living area, 1st Fl
(6-6” runs/20 = 30%)
Zone 3
Master Bdrm Suite, 2nd Fl (4-6” runs/20 = 20%)
Zone 4
Bedrooms, 2nd Fl
(5-6” runs/20 = 25%)
Total: 20-6” runs
