Fan schedule, minimum outdoor air schedule and possibly minimum flow
schedule in the zones. There are also the heating and cooling
availability schedules if needed.
I use the min flow schedules to be 70-100% open (depending on the control
strategy) and min OA schedule to keep OA off. Cannot use the heating
availability schedule since it effects the terminal units also.
Thanks
-Rohini
I have not tried this in eQuest, but from field observations, the typical
morning warm-up sequence, especially for Trane rooftop units with factory
controls is as follows:
The OA damper goes to the minimum position.
The VAV boxes open fully is so equipped. In any case, somehow or another the
HVAC system provides full airflow to the zones during morning warmup or morning
cool down.
The Supply fan VFD ramps up to 60 Hz.
The gas heat in the rooftop unit is enabled to maintain around 85 degrees supply
air temperature.
After the zones meet the zone set-points, the unit returns to cooling mode and
the VAV dampers will modulate accordingly.
I would think in eQuest, the VAV boxes should open fully since the zones are
below set-point. I would use a schedule to define the supply air set-point. I
think you can also use a schedule to define the supply fan speed.
I would be interested to hear how you solve this problem.
Morning warm up is a big source of unmet hours in eQuest, is that what you are having problems with? You can also have problems (if your start up is too late in the morning) with huge spikes in the first hour that are then used to incorrectly auto-size equipment. I generally try to spread the morning warm up over a couple hours by stepping up the thermostat 2 degrees an hour until I hit my set point. In the fan schedule you can also use the -999 flag to give the program a range where you would like the AHUs to start up and the program will pick where the optimum start up point is. Look in the help file for more detail.
Fan schedule, minimum outdoor air schedule and possibly minimum flow
schedule in the zones. There are also the heating and cooling
availability schedules if needed.
>> Christopher Jones, P.Eng.
I use the min flow schedules to be 70-100% open (depending on the control
strategy) and min OA schedule to keep OA off. Cannot use the heating
availability schedule since it effects the terminal units also.
Thanks
-Rohini
I have not tried this in eQuest, but from field observations, the typical
morning warm-up sequence, especially for Trane rooftop units with factory
controls is as follows:
The OA damper goes to the minimum position.
The VAV boxes open fully is so equipped. In any case, somehow or another the
HVAC system provides full airflow to the zones during morning warmup or morning
cool down.
The Supply fan VFD ramps up to 60 Hz.
The gas heat in the rooftop unit is enabled to maintain around 85 degrees supply
air temperature.
After the zones meet the zone set-points, the unit returns to cooling mode and
the VAV dampers will modulate accordingly.
I would think in eQuest, the VAV boxes should open fully since the zones are
below set-point. I would use a schedule to define the supply air set-point. I
think you can also use a schedule to define the supply fan speed.
I would be interested to hear how you solve this problem.
Paul Diglio, CEM, CBCP
Morning warm up is a big source of unmet hours in eQuest, is that what you are having problems with? You can also have problems (if your start up is too late in the morning) with huge spikes in the first hour that are then used to incorrectly auto-size equipment. I generally try to spread the morning warm up over a couple hours by stepping up the thermostat 2 degrees an hour until I hit my set point. In the fan schedule you can also use the -999 flag to give the program a range where you would like the AHUs to start up and the program will pick where the optimum start up point is. Look in the help file for more detail.
Brendan Hall