Installation Guide
24
11-HD15D1-5-EN
Example for determining System Mode:
ZONE 1 ZONE 2 ZONE 3 ZONE 4
Zone LV
60 (clg)
50 (clg)
60 (htg)
50 (htg)
Zone Size
.30
.45
.30
.65
Weighted LV
18
22.5
12
32.5
Cooling Sum
40.5
Heating Sum
44.5
System Mode
Heating
8.3.2 Capacity request (System LV)
System LV is used to determine how much capacity will
be requested. System LV is determined by the zone with
largest load value in the current mode of operation. See
Section 6.2 Load Value for heating and cooling tables for
additional information regarding the load value ranges for
different systems.
Example for determining System Load Value:
ZONE 1 ZONE 2 ZONE 3 ZONE 4
Zone LV
60 (clg)
50 (clg)
80 (clg)
50 (clg)
System LV
80
For VSPD outdoor units and modulating furnaces the
System LV is scaled:
•
SysLV
≤
80 = Raw LV x 1.25
•
SysLV > 80 = (Raw LV x .8333) + 33.33
•
Zone LV is not scaled, only System LV
Example for determining Scaled System Load Value:
ZONE 1 ZONE 2 ZONE 3 ZONE 4
Zone LV
60 (clg)
50 (clg)
80 (clg)
50 (clg)
System LV
80
Scaled System LV
System LV (80) x 1.25 = 100
When zoning is applied the System LV may be inhibited for
the following reasons:
•
The sum of the calling zones is less than or equal to the
current stage of capacity (compressor and gas furnace
operation only)
•
(VSPD systems only) Auxiliary Heat Clamp is enabled
and the sum of the calling zones is less than or equal
to the clamp setting (Installer Settings>Clamp LV for
Auxiliary Heat)
For VSPD systems the speed of the compressor will be
limited based on the air flow capacity of the calling zones.
Oil return or other protection algorithms may override this
clamp
8.3.3 Damper position
The position of the modulating dampers is determined by
the amount of capacity each zone is requesting.
The damper position for each same mode calling zone
follows the calculation below:
•
Zone LV/ System LV = damper position
The minimum opening position is always 25% to reduce air
whistling from a partially opened damper
Zones in the opposite or “off” mode are closed unless the
system has calculated excess air.
Example of how Damper Positions are calculated for non-
VSPD and VSPD systems:
NON-VSPD
ZONE 1 ZONE 2 ZONE 3 ZONE 4
Zone LV
60 (clg)
50 (clg)
40 (clg)
50 (clg)
System LV
60
Damper Position
100%
83%
67%
83%
For non-VSPD systems one damper will always be full open
on a call for capacity and the other dampers will modulate
based on their load value.
VSPD
ZONE 1 ZONE 2 ZONE 3 ZONE 4
Zone LV
60 (clg)
50 (clg)
40 (clg)
50 (clg)
System LV
60
Scaled System LV
Sytem LV (60) x 1.25 =
75
Damper Position
80%
67%
53%
67%
For VSPD cooling or compressor heating the scaling of
the system load value will result in the dampers being in
a less open position than non-VSPD systems. This partial
restriction helps maintain static pressure for improved air
flow distribution.
8.3.4 excess Air Management
The 1050 Control manages excess air without the need
for bypass dampers, dump zones or position stops in the
supply dampers.
The first method of managing excess air is to eliminate or
reduce the excess through equipment stage control and air
flow modulation
•
Equipment Stage Control – For systems with capacity
control, the 1050 Control will limit the capacity request
based on the sum of the calling zones size…insert
chart
•
For systems with capacity control, if the sum of the
calling zones sizes are less than or equal to the
current stage of capacity the system load value will
be inhibited disallowing the next stage of operation
•
For VSPD systems, the speed of the compressor
will be limited based on air flow capabilities of the
calling zones. This inhibit may be overridden during
oil return mode or if the sum of the calling zones
is less than the minimum compressor speed at the
