Step 3: Set The System Static Pressure - Carrier VVT Zone II Installation And Startup Manual

Start-up
6
Click Vent to set the zone damper to its ventilation position. Type the desired damper position next to Vent to
adjust the airflow to the design value. If you do not have a design value, leave the value at 50% for minimum
ventilation.
7
Series Fan Zone Terminals only - If the zone maximum heating airflow design requirements are the same as
cooling, the Heating Max Damper Position should be 100%, same as the Cooling Max Damper Position. If
the heating requirement is less than the cooling requirement, type the appropriate value in Heating Max
Damper Position per the design requirements.
8
If the terminal has ducted reheat, click Reheat Min to force the zone to its reheat damper position. Type the
desired damper position next to Reheat Min to adjust the airflow to its design reheat position.
9
If the zone maximum heating airflow design requirements are the same as cooling, skip this step. If they are
less than cooling, click Heat Max to force the zone to its maximum heating position. Check the zone for
design heating maximum airflow using certified measuring devices. Type the damper position next to Heat
Max.
10 To set the heating minimum airflow, click Heat Min, then type the damper position. We recommend that the
sum of this setting for all zones in the system be equal to the minimum heat CFM (liters/second)
requirements of the air source.
11 Repeat steps 1 through 10 for each zone until all zones have been balanced.

Step 3: Set the system static pressure

For the air source to deliver the required airflow, you must set the bypass controller's static pressure setpoint high
enough to provide the demand but low enough to maintain reasonable noise levels. The bypass controller
maintains static pressure by controlling a damper or a supply fan VFD. You need the following data to set the
static pressure:
•
The air source's design maximum airflow in CFM (liters/second) (manufacturer's data)
•
The system's design external static pressure (inches or water). This is the amount of static pressure that the
air source is designed to deliver at its maximum design airflow in CFM (liters/second) (supplied by the
mechanical design engineer).
• The maximum cooling or heating (whichever is greater) CFM (liters/second) requirements for all zones
connected to the air source
NOTE The air source fan must have been tested and certified that it can deliver the above requirements.
The sum of the maximum CFM (liters/second) requirements of all zones will generally exceed the air source's
maximum CFM (liters/second) rating by 10 to 20%. This is by design and based on a factor known as diversity. It
works on the basis that under normal design heating and cooling conditions, not every zone will be 100% open.
Knowing this, you will need to force open only zones whose sum CFM (liters/second) is equal to the unit design
CFM (liters/second) . With the bypass damper fully closed (0%) or supply fan VFD at 100%, the bypass controller's
static pressure should be the controlling setpoint.
To set the static pressure:
1
Starting with zone furthest from the air source and working towards it, add up the maximum design CFM
(liters/second) airflow of the zones until the sum equals the air source's design CFM (liters/second) (+/-5%).
Note each zone that you included.
2
For each zone noted in step 1, go to Properties > Control Program > Configuration > Service Configuration >
Pressure Dependent Control > Details tab. Click Cool Max or Heat Max (whichever has the highest design
max airflow) to force the damper to its maximum open position.
VVT Zone II Controller
Installation and Start-up Guide
44
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