CET airflow tracking (CetAirFlTck11)

Trend for room supply air volume flow

None/Active

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Trend for room extract air volume flow

None/Active

☑

Trend for room fume hood air volume flow

None/Active

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Trend for room transferred air volume flow

None/Active

☑

Monitoring room transferred air volume flow alarm

None/Active

☑

Trend for room transferred air volume flow alarm

None/Active

☑

Trend for supply air volume flow determination

None/Active

☑

Additional supply air volume flow

▶ If some ventilation equipment adds air to the room that is not measured by a room controller or collected from a segment on a separate controller, indicate that flow with this object. Only applies if the flow is considered constant. If the flow changes, use AirFlSuEffAdd.

AirFlSuAdd

ACnfVal

0.0 [m³/h]
0.0 [ft³/min]
0.00 [l/s]

Additional extract air volume flow

▶ If some extract device removes air from the room that is not measured by a room controller or collected from a segment, indicate that flow with this object. Only applies if the flow is considered constant. If the flow changes, use AirFlExEffAdd.

AirFlExAdd

ACnfVal

0.0 [m³/h]
0.0 [ft³/min]
0.00 [l/s]

Transferred air volume flow setpoint

▶ Controller maintains this value as the difference between supply and extract flow. Set as a positive number.

SpAirFlTrn

ACnfVal

10 [m3/h]

Number of supply air VAV boxes

▶ Enter the number of supply terminals coordinated by this room. For a simple, tracking pair, the value is 1.
For a more complex configuration, include all supply terminals that are in segments of the room. This is the same as the number of supply terminals connected as Group Members.
Do not include airflow values represented as “additional”.

NumVavSu

1

Number of extract air VAV boxes

▶ Enter the number of exhaust coordinated by this controller. For a simple, tracking pair, the value is 1.
Include terminals that are controlled by other controllers, but included in the airflow balance. Do not include fume hoods. This is the same as the number of extract terminals connected as Group Members.
Do not include airflow values represented as “additional”.

NumVavEx

1

Number of fume hoods

▶ Enter the number of fume hoods coordinated by this controller. For a simple, tracking pair, there are no hoods; the value is 0.
For a more complex configuration, include all exhaust devices that are part of this controller’s airflow balance, but the flow rate is set independently of this room controller. This is the same as the number of fume hoods connected as Group Members.
Do not include airflow values represented as “additional”.

NumFh

0

Room pressurization mode

▶ Set the direction of pressurization for the room, and the direction of net air transfer between the room and surrounding spaces.

1:Neutral
▶ Supply flow and exhaust are equal. Contamination is not controlled. Alarm is disabled.
2:Positive pressure
▶ Supply flow is more than extract. Used to keep contaminants out of the room.
3:Negative pressure
▶ Extract flow is more than supply. Used to contain contaminants in the room.

PRMod

1:Neutral

Tracking mode

▶ Select the flow tracking algorithm according to project specifications. If it is not specified, select according to PRMod.

1:Supply air tracks extract air
▶ Typically chosen for negatively pressurized rooms. Controller calculates exhaust flow setpoint from room demands and calculates supply flow setpoint from exhaust.
2:Extract air tracks supply air
▶ Typically chosen for positively pressurized rooms. Controller calculates supply flow setpoint from room demands and calculates exhaust flow setpoint from supply.

TckMod

1:Supply air tracks extract air

Tracking method

▶ This is a detail of the flow tracking algorithm. Use the default value unless project specifications clearly direct otherwise. Setpoint tracking is both faster and more stable than flow tracking. Some people choose flow tracking for the certainty of tracking the actual flow.

1:Setpoint
▶ Typically chosen setting. Use setpoint of leading flow to calculate setpoint of tracking flow.
2:Air volume flow
▶ Use measured value of leading flow to calculate setpoint of tracking flow.

TckMthd

1:Setpoint

Time for increasing air volume flow request
▶ Rate limiting feature - the amount of time needed to increase the supply airflow demand from 0 to maximum. (applies to changes driven by ventilation or temperature control; does not apply to changes driven by fume hoods)

This parameter regulates the rate of change when changes in room airflow are sudden. A longer time makes the changes more gradual and reduces the chance of temporary imbalance of supply and extract. If the customer is concerned about briefly reversing pressurization, consider longer time.

Adjust this parameter if the room does not maintain correct pressurization during transition of ventilation or temperature setpoints.

TiIcrAflReq

10 [s]

Time for decreasing air volume flow request
▶ Rate limiting feature - the amount of time needed to decrease the supply airflow demand from maximum down to 0. (for additional information see TiIcrAflReq)

Adjust this parameter if the room does not maintain the correct pressurization during transitioning ventilation or temperature setpoints.

TiDcrAflReq

10 [s]

Room supply response to failed supply air volume flow

▶Specifies action at all supply terminals in the room, if flow data is unavailable from one of them. No affect if there is only 1 supply terminal.
"Unavailable" means flow sensing object shows unreliable condition or communication with the segment is lost.

In some facilities failure modes are carefully engineered and tested to produce a very reliable system. In those cases, the HVAC design engineer should choose this failure response.

For customers less interested in operating details, the default Hold setting is often a good choice as the least disruptive response. This maintains setpoint at the level it had before the failure.

Normal continues performing algorithms without regard for the failure.

Max or Min may be selected as the surest way to maintain the desired direction of pressurization. However, the pressurization level and flow levels in the room may be extreme.

Zero is selected for facilities where the desired failure mode is to isolate the room. The setpoint goes to zero and the damper closes.

1:Normal
2:Maximum
3:Minimum
4:Zero
5:Hold

SuRAirFlFailSu

5:Hold

Room supply response to failed extract air volume flow
▶ Specifies action at all supply terminals in the room, if flow data is unavailable from one of the extract terminals. "Unavailable" means the flow sensing object shows unreliable condition or that communication with the segment is lost.

Enumeration see SuRAirFlFailSu

SuRAirFlFailEx

5:Hold

Room extract response to failed extract air volume flow
▶ Specifies action at all extract terminals in the room, if flow data is unavailable from one of them (no effect if there is only 1 extract terminal). "Unavailable" means the flow sensing object shows unreliable condition or that communication with the segment is lost.

Enumeration see SuRAirFlFailSu

ExRAirFlFailEx

5:Hold

Room extract response to failed supply air volume flow
▶ Specifies action at all extract terminals in the room, if flow data is unavailable from one of the supply terminals. "Unavailable" means the flow sensing object shows unreliable condition or that communication with the segment is lost.

Enumeration see SuRAirFlFailSu

ExRAirFlFailSu

5:Hold

Transferred air volume flow alarm configuration
▶ Set according to customer’s need to monitor room pressurization.

1:Disabled
▶ Alarm never trips. May be a good choice if customer uses some other means to monitor pressurization. May be selected temporarily for special circumstances such as maintenance or mechanical breakdown.
2:Alarm on high value
▶ Only alarms when transfer is too high, but not when it’s too small or in the wrong direction. Usually not necessary, because excess airflow transfer does not usually cause contamination problems. May be useful in scenarios with complex levels of pressurization among spaces. In such a case, too much net transfer flow could reverse flow at one of the boundaries. This is unusual.
3:Alarm on low value
▶ Usually the best choice for monitoring pressurization. Sets the alarm when transfer flow is too small or in the wrong direction. Does not alarm when transfer flow is higher than necessary.
4:Alarm on high or low value
▶ Usually not necessary, because excess airflow transfer does not usually cause contamination problems. May be useful in scenarios with complex levels of pressurization among spaces.

AirFlTrnAlmCnf

1:Disabled

Delay for transferred air volume flow alarm

▶ Set according to customer’s need to monitor room pressurization. In most applications a brief lapse in transfer flow is not a contamination control issue.
Set the delay long enough that normal dynamic flow changes do not cause unnecessary alarms.

DlyAirFlTrnAlm

30 [s]

Tolerance for transferred air volume flow alarm

▶ Set according to customer’s need to monitor room pressurization. Set large enough that normal variations in flow measurements do not trip the alarm.
Set small enough that operating staff are informed when the system is out of working order.
A value of approximately 50% of SpAirFlTrn is often appropriate.

TolAirFlTrnAlm

70.0 [m³/h]
41.2 [ft³/min]
19.44 [l/s]

Transferred air volume flow warning configuration
▶ Set according to customer’s need to monitor room pressurization.
1:Disabled
▶ Warning never trips. May be a good choice if customer uses some other means to monitor pressurization. May be selected temporarily for special circumstances such as maintenance or mechanical breakdown.
2:Warning on high value
▶ Only warns when transfer is too high, but not when it’s too small or in the wrong direction. Usually not necessary, because excess airflow transfer does not usually cause contamination problems.
3:Warning on low value
▶ Usually the best choice for monitoring pressurization. Sets the warning when transfer flow is too small or in the wrong direction. Does not warn when transfer flow is higher than necessary.
4:Warning on high or low value
▶ Usually not necessary, because excess airflow transfer does not usually cause contamination problems. May be useful in scenarios with complex levels of pressurization among spaces.

AflTrnWarnCnf

1:Disabled

Delay for transferred air volume flow warning
▶ Set according to customer’s need to monitor room pressurization. In most applications a brief lapse in transfer flow is not a contamination control issue.
Set the delay long enough that normal dynamic flow changes do not cause unnecessary warnings.

DlyAflTrnWarn

30 [s]

Tolerance for transferred air volume flow warning
▶ Set according to customer’s need to monitor room pressurization. Set small enough that operating staff can be informed that the system is not performing optimally and may need adjustment.

TolAflTrnWarn

35.0 [m³/h]
20.7 [ft³/min]
9.72 [l/s]

Reset fume hood setpoint configuration
▶ Set to Yes to allow the room to request additional exhaust from fume hoods. The room will only request additional exhaust from the fume hoods if the extract terminals are at maximum and the temperature or ventilation demands are not being met. The parameters in FhSpEh for each fume hood also need to be configured for this feature to function.

0:No
1:Yes

RstSpFhCnf

0:No

Fume hood use exceeded configuration
▶ Set to Yes to enable fume hood use alarm.

Typically used when there are multiple fume hoods in a room and the room supply cannot provide enough makeup air if all the fume hoods are open.

If set to Yes and the total fume hood exhaust air flow for the room is greater than FhAirFlUseLm the fume hood ODP will provide an indication that the limit has been exceeded and the fume hood exhaust air volume should be reduced (close the sash).

0:No
1:Yes

FhUseExcdCnf

0:No

Fume hood air volume flow use limit

▶ Value specified / chosen by customer. Alarm is indicated when sum of fume hood flows in the room exceeds this value.

FhAirFlUseLm

0.0 [m³/h]
0.0 [ft³/min]
0.00 [l/s]

Air volume flow unit

▶ Defined by selected engineering unit – do not change.

AirFlUnit

[m³/h]
[ft³/min]
[l/s]