.Buildings.Controls.OBC.ASHRAE.G36.TerminalUnits.Reheat.Subsequences.Alarms

Information

This block outputs alarms of terminal unit with reheat. The implementation is according to the Section 5.6.6 of ASHRAE Guideline 36, May 2020.

Low airflow

  1. If the zone is in occupied mode and after the AHU supply fan has been enabled for staTim, if the measured airflow VDis_flow is less than 70% of setpoint VActSet_flow for 5 minutes (lowFloTim) while the setpoint is greater than zero, generate a Level 3 alarm.
  2. If the zone is in occupied mode and after the AHU supply fan has been enabled for staTim, if the measured airflow VDis_flow is less than 50% of setpoint VActSet_flow for 5 minutes (lowFloTim) while the setpoint is greater than zero, generate a Level 2 alarm.
  3. If a zone has an importance multiplier (staPreMul) of 0 for its static pressure reset Trim-Respond control loop, low airflow alarms shall be suppressed for that zone.

Low-discharging air temperature

  1. If the zone is in occupied mode and if heating hot-water plant is proven on (u1HotPla=true), and the discharge temperature (TDis) is 8 °C (15 °F) less than the setpoint (TDisSet) for 10 minuts (lowTemTim), generate a Level 3 alarm.
  2. If the zone is in occupied mode and if heating hot-water plant is proven on (u1HotPla=true), and the discharge temperature (TDis) is 17 °C (30 °F) less than the setpoint (TDisSet) for 10 minuts (lowTemTim), generate a Level 2 alarm.
  3. If a zone has an importance multiplier (hotWatRes) of 0 for its hot-water reset Trim-Respond control loop, low discharing air temperature alarms shall be suppressed for that zone.

Airflow sensor calibration

If the fan serving the zone has been OFF (u1Fan=false) for 10 minutes (fanOffTim), and airflow sensor reading VDis_flow is above 10% of the cooling maximum airflow setpoint VCooMax_flow, generate a Level 3 alarm.

Leaking damper

If the damper position (uDam) is 0% and airflow sensor reading VDis_flow is above 10% of the cooling maximum airflow setpoint VCooMax_flow for 10 minutes (leaFloTim) while the fan serving the zone is proven on (u1Fan=true), generate a Level 4 alarm.

Leaking valve

If the valve position (uVal) is 0% for 15 minutes (valCloTim), discharing air temperature TDis is above AHU supply temperature TSup by 3 °C (5 °F), and the fan serving the zone is proven on (u1Fan=true), gemerate a Level 4 alarm.

Revisions


Generated at 2024-11-23T19:25:52Z by OpenModelicaOpenModelica 1.24.2 using GenerateDoc.mos