Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
Problem solved. I had AHU fan schedule on/off set to '0' during unoccupied hours, so even though my setback temp is 64F, the system is set to 0 (off) during unoccupied times, so its setpoint is the eQuest default for '0', -999F. Hopefully this helps someone down the road.
| | 2 | No.2 Revision |
Problem solved. I had AHU fan schedule on/off set to '0' during unoccupied hours, so even though my setback temp is 64F, the system is set to 0 (off) during unoccupied times, so its setpoint is the eQuest default for '0', -999F. Hopefully this helps someone down the road.
Edit: The actual problem was NIGHT-CYCLE-CTRL in the AHU fan settings under "Night Cycle Fan Control". I had to switch it to "Cycle On Any". In doing so, you can leave fan schedule "0's" during unoccupied hours. Here is the info from the help file: The U-name of the SCHEDULE instruction giving the time periods (hours and days) during which this system's fans (supply, return, and exhaust) are operating and not operating. If the hourly values in the SCHEDULE that is referenced by FAN-SCHEDULE are positive, such as 1, the fans are on. If the hourly SCHEDULE values are 0, the fans are off but may be turned on by NIGHT-CYCLE-CTRL if ZONE temperatures warrant it. If the hourly SCHEDULE values are negative, such as -1, the fans are not permitted to be on for any reason. If you don't specify a SCHEDULE, the program will assume the fans run continuously. When the fans are scheduled to be off, baseboard units (if specified) can be operational.
| | 3 | No.3 Revision |
Problem solved. I had AHU fan schedule on/off set to '0' during unoccupied hours, so even though my setback temp is 64F, the system is set to 0 (off) during unoccupied times, so its setpoint is the eQuest default for '0', -999F. Hopefully this helps someone down the road.
Edit: The actual problem was IN addition, it seems you need to change NIGHT-CYCLE-CTRL in the AHU fan settings under "Night Cycle Fan Control". I had to switch it to "Cycle On Any". In doing so, you can leave fan schedule "0's" during unoccupied hours. . Here is the info from the help file: The U-name of the SCHEDULE instruction giving the time periods (hours and days) during which this system's fans (supply, return, and exhaust) are operating and not operating. If the hourly values in the SCHEDULE that is referenced by FAN-SCHEDULE are positive, such as 1, the fans are on. If the hourly SCHEDULE values are 0, the fans are off but may be turned on by NIGHT-CYCLE-CTRL if ZONE temperatures warrant it. If the hourly SCHEDULE values are negative, such as -1, the fans are not permitted to be on for any reason. If you don't specify a SCHEDULE, the program will assume the fans run continuously. When the fans are scheduled to be off, baseboard units (if specified) can be operational.
