.Buildings.Controls.OBC.ASHRAE.G36.TerminalUnits.DualDuctSnapActing.Subsequences.SystemRequests

Information

This sequence outputs the system reset requests for snap-acting controlled dual-duct terminal unit. The implementation is according to the Section 5.11.8 of ASHRAE Guideline 36, May 2020.

Cooling SAT reset requests yZonCooTemResReq

1. If the zone temperature TZon exceeds the zone cooling setpoint TCooSet by 3 °C (5 °F)) for 2 minutes and after suppression period (uAftSupCoo=true) due to setpoint change per G36 Part 5.1.20, send 3 requests (yZonCooTemResReq=3).
2. Else if the zone temperature TZon exceeds the zone cooling setpoint TCooSet by 2 °C (3 °F) for 2 minutes and after suppression period (uAftSupCoo=true) due to setpoint change per G36 Part 5.1.20, send 2 requests (yZonCooTemResReq=3).
3. Else if the cooling loop uCoo is greater than 95%, send 1 request (yZonCooTemResReq=1) until uCoo is less than 85%.
4. Else if uCoo is less than 95%, send 0 request (yZonCooTemResReq=0).

Cold-duct static pressure reset requests yColDucPreResReq

1. If the measured airflow VColDucDis_flow is less than 50% of setpoint VColDuc_flow_Set while the setpoint is greater than zero and the damper position uCooDam is greater than 95% for 1 minute, send 3 requests (yColDucPreResReq=3).
2. Else if the measured airflow VColDucDis_flow is less than 70% of setpoint VColDuc_flow_Set while the setpoint is greater than zero and the damper position uCooDam is greater than 95% for 1 minute, send 2 requests (yColDucPreResReq=2).
3. Else if the damper position uCooDam is greater than 95%, send 1 request (yColDucPreResReq=1) until uDam is less than 85%.
4. Else if the damper position uCooDam is less than 95%, send 0 request (yColDucPreResReq=0).

Heating SAT reset requests yZonHeaTemResReq

1. If the zone temperature TZon is below the zone heating setpoint THeaSet by 3 °C (5 °F)) for 2 minutes and after suppression period (uAftSupHea=true) due to setpoint change per G36 Part 5.1.20, send 3 requests (yZonHeaTemResReq=3).
2. Else if the zone temperature TZon is below the zone heating setpoint THeaSet by 2 °C (3 °F) for 2 minutes and after suppression period (uAftSupHea=true) due to setpoint change per G36 Part 5.1.20, send 2 requests (yZonHeaTemResReq=3).
3. Else if the heating loop uHea is greater than 95%, send 1 request (yZonHeaTemResReq=1) until uHea is less than 85%.
4. Else if uHea is less than 95%, send 0 request (yZonHeaTemResReq=0).

Hot-duct static pressure reset requests yHotDucPreResReq

1. If the measured airflow VHotDucDis_flow is less than 50% of setpoint VHotDuc_flow_Set while the setpoint is greater than zero and the damper position uHeaDam is greater than 95% for 1 minute, send 3 requests (yHotDucPreResReq=3).
2. Else if the measured airflow VHotDucDis_flow is less than 70% of setpoint VHotDuc_flow_Set while the setpoint is greater than zero and the damper position uHeaDam is greater than 95% for 1 minute, send 2 requests (yHotDucPreResReq=2).
3. Else if the damper position uHeaDam is greater than 95%, send 1 request (yHotDucPreResReq=1) until uHeaDam is less than 85%.
4. Else if the damper position uHeaDam is less than 95%, send 0 request (yHotDucPreResReq=0).

Heating-fan requests

Send the heating fan that serves the zone a heating-fan request as follows:

1. If the heating loop is greater than 15%, send 1 request until the heating loop is less than 1%.
2. Else if the heatling loop is less than 15%, send 0 requests.

Revisions

• August 1, 2020, by Jianjun Hu:
  First implementation.