Table 12 — Secondary Damper Service Configuration Screen
DESCRIPTION | DEFAULT | POINT NAME |
Zone Pressure Control | Dsable | ZPCNTL |
Dual Duct Type | 0 | DDTYPE |
Secondary Duct Size |
|
|
Inlet Diameter | 6.0 in. | SRNDSZ |
Inlet Area | 0.0 sq. in. | SSQA |
Probe Multiplier | 2.443 | SPMF |
Calibration Gain | 1.000 | CAL_GAIN |
Offset | 0 cfm | SOFFSET |
CW Rotation | Close | DMPDIR |
Secondary Duct Size — The Secondary Duct Size setting is used to input the inlet diameter of the terminal, if used with a round inlet. The Inlet Area configuration is used for oval or rectangular inlets. The zone controller will use the larger value for CFM calculations if both values are configured.
Secondary Duct Size |
|
(Inlet Diameter): Units | Inches |
Range | 3.0 to 24.0 |
Default Value | 6.0 |
Inlet Area — The Inlet Area configuration is used if the termi- nal has an oval or rectangular inlet. The Primary Inlet Size configuration is used for round inlets. The zone controller will use the larger value for CFM calculations if both values are
configured. |
|
|
Inlet Area: | Units | Square Inches |
| Range | 0.0 to 500.0 |
| Default Value | 0.0 |
Probe Multiplier — This configuration is used to input a fac- tor for the velocity pressure probe characteristics installed in the inlet. All averaging probes will have some aerodynamic characteristics which will amplify the pressure difference read at the inlet of the terminal. The default of 2.443 is the correct value to use if the probe is a Carrier probe in a 35 or 45 Series terminal.
The formula for calculating velocity using an Ideal probe is: Velocity = 4005* SQRT (Velocity Pressure)
Most manufactures will provide a probe constant for the probe supplied. For example, Velocity = 2213*SQRT(Velocity Pressure). To calculate the number to input in this decision (Probe Multiplier) use the formula. (4005/2213)2 = 3.3. So you would use 3.3 in place of 2.443 for a probe with a probe con- stant of 2213.
An easy way to determine the probe constant for a probe without documentation is to measure the velocity pressure with a Magnahelic gage. Open the damper and adjust the static pres- sure until you have one inch of velocity pressure on the Magna- helic gage. Measure the total CFM of air being produced. The CFM just measured divided by the inlet area in feet should equal the probe constant for the formula. Velocity = (CFM just measured/inlet area) * SQRT (1.0). Now use the constant that was empirically derived to determine the probe multiplier (4005/(CFM at 1.0 Inch/Inlet area))2 = Probe Multiplier.
Probe Multiplier: Range | 0.250 to 9.999 |
Default Value | 2.443 |
Calibration Gain — Air terminal testing by industry standards is done with straight duct, upstream of the terminal. Since most applications do not get installed in this manner, the actual air- flow from the terminal at balancing may not equal the reading from the zone controller.
The calibration gain is used for the fine tuning adjustments which might need to be made to the airflow calculation.
If the Calibration Gain must be configured manually. It is determined as a percentage up or down that the CFM indicated
will be offset. A number of .95 will cause the maximum air- flow calculated to be reduced to 95% of the value. A Calibra- tion Gain of 1.00 will cause no change. A number of 1.05 would cause readings to become 5% higher.
Any error in reading at minimum airflow is adjusted by cal- culating the Offset configuration value.
Calibration Gain: Range | 0.000 to 9.999 |
Default Value | 1.000 |
Offset — The Offset configuration is included for precision applications where the minimum airflow is critical and not zero. The cfm will be offset by the value entered in the Mini- mum Cfm variable and will zero at the value entered in the Maximum Cfm variable. There will be a linear relationship be- tween the two set points.
Offset: | Units | cfm |
| Range | |
| Default Value | 0 |
Clockwise Rotation — This configuration is used to define what effect a clockwise rotation of the actuator will have on the damper. If the actuator rotates clockwise to closed position, the configuration should be set to Close. If the actuator rotates clockwise to open, the configuration should be set to open. This configuration is used to change the rotation of the actuator so that the damper transducer calibration will work properly. The actuator does not have to be reinstalled nor any switches changed to reverse the action.
Clockwise |
|
|
Rotation: | Range | Close/Open |
| Default Value | Close |
Maintenance Table Menu Screen — The Mainte- nance Table Menu screen allows the user to select one of 4 available maintenance tables: the Linkage Maintenance Table, the Occupancy Maintenance Table, the Zone Air Balance Table, and the Zone Maintenance Table.
LINKAGE MAINTENANCE TABLE — The Linkage Maintenance table is used to view the zone linkage variables. See Table 13.
→Air Source Bus Number — This variable will display the bus number of the air source that the zone controller will be com- municating Linkage to, if this zone is the Linkage Master.
Air Source |
|
|
Bus Number: | Range | 0 to 239 |
| Default Value | 0 |
| Network Access | None |
→Air Source Element Number — This variable will display the Element Address of the Air Source that the zone controller will be communicating Linkage to, if this zone is the Linkage Master.
Air Source |
|
Element Number: Display Range | 1 to 239 |
Default Value | 0 |
Network Access | None |
43 | 501 |
