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38
VVT Zone Controller
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 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 (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 (supplied by the mechanical
design engineer).
•
The maximum cooling or heating (whichever is greater) CFM 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 requirements of all zones will generally exceed the air source's maximum CFM
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 is equal to the unit design CFM. 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
airflow of the zones until the sum equals the air source’s design CFM (+/-5%). Note each zone that you
included.
2
For each zone noted in step 1, go to
Properties
>
Equipment
>
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.
3
In the tree, select the Bypass controller, then go to
Properties
>
Equipment
>
Status
. Note the
Static
Pressure
value, then go to
Unit Configuration
>
Bypass Control
>
Details
tab.
○
If
Damper Position
is 0% or
VFD Output
is 100%, enter the static pressure in the
Duct Static
Pressure Setpoint
field.
○
If the
Damper Position
is not 0% or
VFD Output
is not 100%, enter the static pr.1” in the
Duct Static Pressure Setpoint
field. Wait 1–2 minutes, then verify that the
Damper Position
is 0% or
VFD Output
is 100%. If not, repeat the process, adding .05” to the previous
Duct Static Pressure
Setpoint
until the
Damper Position
is 0% or
VFD Output
is 100%.
Summary of Contents for OPN-VVTZC
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