.Buildings.Controls.OBC.ASHRAE.G36.FanCoilUnits.Subsequences.PlantRequests

Information

This sequence outputs the system reset requests for fan coil unit. The implementation is according to the Section 5.22.8 of ASHRAE Guideline 36, 2021.

If there is a chilled-water coil (have_chiWatCoi=true), chilled water reset requests yChiWatResReq

1. If the supply air temperature TAirSup exceeds the supply air temperature set point TSupSet by 5.56 °C (10 °F) for 5 minutes, send 3 requests.
2. If the supply air temperature TAirSup exceeds TSupSet by by 2.78 °C (5 °F) for 5 minutes, send 2 requests.
3. Else if the chilled water valve position uCooCoi_actual is greater than 0.95, send 1 request until uCooCoi_actual is less than 0.85.
4. Else if the chilled water valve position uCooCoi_actual is less than 0.85, send 0 requests.

If there is a chilled-water coil and chilled water plant, chiller plant request yChiPlaReq

Send the chiller plant that serves the system a chiller plant request as follows:

1. If the chilled water valve position uCooCoi_actual is greater than 0.95, send 1 request until the uCooCoi_actual is less than 0.1.
2. Else if the chilled water valve position uCooCoi_actual is less than 0.1, send 0 request

If there is a hot-water coil (have_hotWatCoi=true), hot-water reset requests yHotWatResReq

1. If the supply air temperature TAirSup is 17 °C (30 °F) less than the supply air temperature set point TSupSet for 5 minutes, send 3 requests.
2. Else if the supply air temperature TAirSup is 8 °C (15 °F) less than TSupSet for 5 minutes, send 2 requests.
3. Else if the hot water valve position uHeaCoi_actual is greater than 0.95, send 1 request until the uHeaCoi_actual is less than 0.85.
4. Else if the hot water valve position uHeaCoi_actual is less than 0.85, send 0 request.

If there is a hot-water coil and heating hot-water plant, heating hot-water plant requests yHotWatPlaReq

Send the heating hot-water plant that serves the air handling unit a heating hot-water plant request as follows:

1. If the hot water valve position uHeaCoi_actual is greater than 0.95, send 1 request until the hot water valve position is less than 0.1.
2. If the hot water valve position uHeaCoi_actual is less than 0.1, send 0 requests.

Revisions

• May 6, 2022, by Karthik Devaprasad:
  First implementation.