I checked the following in the i/O manual
AirTerminal:SingleDuct:VAV:Reheat Field: Damper Heating Action
This object only has one field for the reheat heater used in the cooling mode and should have 'reverse' in this field.
There are two versions. The gas and electric heater version is what I have described.
The water coil version has another maximum value which can be set.
If the dead band temperature of the VAV box is below the heating set point value, the final zone temperature may stop at the heating setpoint instead of the cooling setpoint value of the zone thermostat, unless the program has a flag to indicate that the system is still in the cooling mode.
Dr. Li
To: energyplus_support@xxxxxxxxxxxxxxx
From: yli006@xxxxxxxxxxx
Date: Wed, 22 Aug 2012 13:11:55 -0400
Subject: RE: [EnergyPlus_Support] Damper action according to ASHRAE 90.1
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AirTerminal:SingleDuct:VAV:Reheat Field: Damper Heating Action
This object only has one field for the reheat heater used in the cooling mode and should have 'reverse' in this field.
There are two versions. The gas and electric heater version is what I have described.
The water coil version has another maximum value which can be set.
If the dead band temperature of the VAV box is below the heating set point value, the final zone temperature may stop at the heating setpoint instead of the cooling setpoint value of the zone thermostat, unless the program has a flag to indicate that the system is still in the cooling mode.
Dr. Li
To: energyplus_support@xxxxxxxxxxxxxxx
From: yli006@xxxxxxxxxxx
Date: Wed, 22 Aug 2012 13:11:55 -0400
Subject: RE: [EnergyPlus_Support] Damper action according to ASHRAE 90.1
Reverse or Forward (Normal) refers to response of a component with the control. It can be applied to the dampers, valves, or coils.
When the damper opening increases, and the controlled temperature decreases, rthe damper is in 'reverse' action and cooling mode. (More air, lower temperature) At this configuration, the closing (number decreases) of the damper would increase the temperature and it is still in the cooling mode. A cooling coil will show a similar result and is therefore in reverse mode.
Normally, an increase in control is expected to increase the resultant response. (Damper or coils in Heating mode)
For the VAV reheat heater, when it turns on when the damper is in 'reverse' (cooling) mode, it is in the cooling reduction mode and the heat involved is listed separatly as the reheat operation energy.
When the damper is in the normal (heating) mode, the reheat heater would not be turned on at the minimum damper position. This is the reason why I said the reheat heater does not follow the heating set point, and would operate to the cooling setpoint value (in the reverse mode)
When the damper is at the maximum in the cooling mode, the reheat heater would not come on, because more cooling is required. (Warning - setpoint not met condition).
When the damper is at the maximum in the heating mode (Normal), the reheat heater will act as a normal zone heater to continue heating the zone to the heating set point.
."It means that for VAV with reheat we have to use the option "Reverse" (Object: AirTerminal:SingleDuct:VAV:Reheat Field: Damper Heating Action), doesn't it?"
This question need not be related to the ASHRAE guideline. I am not sure of the answer. There may be two fields in the object. The cooling section should be "reverse", and the heating section should be "normal".
I have not yet look at the setpoint manager way to control the VAV damper with reheat. My hunch is that two cntrollers are required one for heating and one for cooling.
The reheat heater still increases the temperature. But the reverse is applied to the damper. That is why I call this heating the cooling reduction function, as the control had over-shot the cooling setpoint, and should continued to be controlled by the cooling setpoint..
I know I am long winded. This is the only way to learn.
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: direzionecontraria@xxxxxxxx
Date: Wed, 22 Aug 2012 10:59:37 +0000
Subject: [EnergyPlus_Support] Damper action according to ASHRAE 90.1
When the damper opening increases, and the controlled temperature decreases, rthe damper is in 'reverse' action and cooling mode. (More air, lower temperature) At this configuration, the closing (number decreases) of the damper would increase the temperature and it is still in the cooling mode. A cooling coil will show a similar result and is therefore in reverse mode.
Normally, an increase in control is expected to increase the resultant response. (Damper or coils in Heating mode)
For the VAV reheat heater, when it turns on when the damper is in 'reverse' (cooling) mode, it is in the cooling reduction mode and the heat involved is listed separatly as the reheat operation energy.
When the damper is in the normal (heating) mode, the reheat heater would not be turned on at the minimum damper position. This is the reason why I said the reheat heater does not follow the heating set point, and would operate to the cooling setpoint value (in the reverse mode)
When the damper is at the maximum in the cooling mode, the reheat heater would not come on, because more cooling is required. (Warning - setpoint not met condition).
When the damper is at the maximum in the heating mode (Normal), the reheat heater will act as a normal zone heater to continue heating the zone to the heating set point.
."It means that for VAV with reheat we have to use the option "Reverse" (Object: AirTerminal:SingleDuct:VAV:Reheat Field: Damper Heating Action), doesn't it?"
This question need not be related to the ASHRAE guideline. I am not sure of the answer. There may be two fields in the object. The cooling section should be "reverse", and the heating section should be "normal".
I have not yet look at the setpoint manager way to control the VAV damper with reheat. My hunch is that two cntrollers are required one for heating and one for cooling.
The reheat heater still increases the temperature. But the reverse is applied to the damper. That is why I call this heating the cooling reduction function, as the control had over-shot the cooling setpoint, and should continued to be controlled by the cooling setpoint..
I know I am long winded. This is the only way to learn.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: direzionecontraria@xxxxxxxx
Date: Wed, 22 Aug 2012 10:59:37 +0000
Subject: [EnergyPlus_Support] Damper action according to ASHRAE 90.1
In "User's Manual for ANSI/ASHRAE/IESNA Standard 90.1-2007" I found the following sentence:
"The simulation model for the baseline building shall include this air volume as the minimum to be delivered to the space during occupied periods and reheating of the cool air shall not occur until air has been reduced to this minimum, but the box may open up further for heating under high heating loads.".
It is relative to paragraph G3.1.3.13 of ASHRAE 90.1-2007.
It means that for VAV with reheat we have to use the option "Reverse" (Object: AirTerminal:SingleDuct:VAV:Reheat Field: Damper Heating Action), doesn't it?
Regards
"The simulation model for the baseline building shall include this air volume as the minimum to be delivered to the space during occupied periods and reheating of the cool air shall not occur until air has been reduced to this minimum, but the box may open up further for heating under high heating loads.".
It is relative to paragraph G3.1.3.13 of ASHRAE 90.1-2007.
It means that for VAV with reheat we have to use the option "Reverse" (Object: AirTerminal:SingleDuct:VAV:Reheat Field: Damper Heating Action), doesn't it?
Regards
__._,_.___
Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
The primary EnergyPlus web site is found at:
http://www.energyplus.gov
The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/
Attachments are currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
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