With a PSZ or PVVT system type in eQUEST, is it possible to define a different supply airflow in heating vs cooling mode (ex. 800 CFM in cooling mode; 550 CFM in heating mode)? If so, how can this be done? Thanks!
Hi Phil,
No, not exactly. But you can specify different system MIN-FLOW-RATIOs for cooling mode and heating mode.
For your example, you can set HMIN-FLOW-RATIO to 550/800 = 0.6875.
You would also need to change the FAN-CONTROL to something other than CONSTANT-VOLUME for PSZ systems.
For VAVS and PVAVS systems, you also have the option of specifying an HMAX-FLOW-RATIO, but not greater than 1.0.
You can change these values at the zone level as well.
Regards,
~Bill
William Bishop, PE, BEMP, BEAP, CEM, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer
[cid:image007.jpg at 01D316AF.D61A6BE0] [cid:image008.jpg at 01D316AF.D61A6BE0]
134 South Fitzhugh Street Rochester, NY 14608
T: (585) 698-1956 F: (585) 325-6005
bbishop at pathfinder-ea.com www.pathfinder-ea.com
[http://png-5.findicons.com/files/icons/977/rrze/720/globe.png]Carbon Fee and Dividend - simple, effective, and market-based.
How about, for PVVT, is it possible to set a unique supply flow per cooling (or heating) stage? Could the hourly value of the COOL-STAGE keyword be used in a BDL expression to dictate SUPPLY-FLOW?
Phil, what you're describing as an expression that reads in an hourly variable is I believe what my predecessors in doe2 history would coin as an Input Function. Not something we can do in doe 2.2+ (presently), but it comes up from time to time as something some would like to see resurface and become a feature accessible through the eQUEST interface. Further reading and examples of functions are available in your help file (doe2 reference manual) under the entry Volume 3: Topics > Building Description Language > Input Functions.
Short of rolling back and doing your project with such an Input Function in 2.1e, I don't think there is a way to accomplish this for PVVT.
VAVS and PVAVS systems have the option of using HMAX-FLOW-RATIO to define heating mode supply air ratios at a central/zonal level, but since PVAVS is distinct from PVVT in not really being able to supply heated air from the central unit based on heating/cooling mode as PVVT is designed, I don't think you want to switch system types.
And just to be sure, I checked and confirmed that HMAX-FLOW-RATIO has zero impact on PVVT systems with a dummy model.
~Nick
[cid:image001.png at 01D31C1D.898DFE90]
Nick Caton, P.E., BEMP
Senior Energy Engineer
Regional Energy Engineering Manager
Energy and Sustainability Services
Schneider Electric
D 913.564.6361
M 785.410.3317
F 913.564.6380
E nicholas.caton at schneider-electric.com
15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States
Phil,
I suggest experimenting with the AIR/TEMP-CONTROL settings available for PVVT systems. Try STAGED-VOLUME and adjust the capacity fractions to try to match the desired air flows.
If you want convenient access to the NUM-COOL-STAGES and NUM-HEAT-STAGES keywords (applicable to STAGED-VOLUME PVVT systems), modify your eQUEST installation as follows:
- Go to your eQUEST 3-64 or 3-65 Data folder
- Open the Screens folder
- Save a backup version of the BDLDialogs.txt file such as "BDLDialogs-backup.txt"
- Open your BDLDialogs.txt file with a text editor
- Search for the string, "HEAT-STAGES-DT , 3". It occurs twice.
- Insert the lines in the attached file to this email, right above the ENDCASE that follows the HEAT-STAGES-DT lines.
- Repeat the insert step for both occurrences of "HEAT-STAGES-DT , 3"
- Save the BDLDialogs.txt file
- Your Staged-Volume tab will look like this when you use STAGED-VOLUME control:
[cid:image005.png at 01D31CD4.CBDC8E30]
Regards,
~Bill
William Bishop, PE, BEMP, BEAP, CEM, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer
[cid:image006.jpg at 01D31CD4.CBDC8E30] [cid:image008.jpg at 01D31CD4.CBDC8E30]
134 South Fitzhugh Street Rochester, NY 14608
T: (585) 698-1956 F: (585) 325-6005
bbishop at pathfinder-ea.com www.pathfinder-ea.com
[http://png-5.findicons.com/files/icons/977/rrze/720/globe.png]Carbon Fee and Dividend - simple, effective, and market-based.
Hi Phil,
No, not exactly. But you can specify different system MIN-FLOW-RATIOs for cooling mode and heating mode.
For your example, you can set HMIN-FLOW-RATIO to 550/800 = 0.6875.
You would also need to change the FAN-CONTROL to something other than CONSTANT-VOLUME for PSZ systems.
For VAVS and PVAVS systems, you also have the option of specifying an HMAX-FLOW-RATIO, but not greater than 1.0.
You can change these values at the zone level as well.
Regards,
~Bill
William Bishop, PE, BEMP, BEAP, CEM, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer
[cid:image007.jpg at 01D316AF.D61A6BE0] [cid:image008.jpg at 01D316AF.D61A6BE0]
134 South Fitzhugh Street Rochester, NY 14608
T: (585) 698-1956 F: (585) 325-6005
bbishop at pathfinder-ea.com www.pathfinder-ea.com
[http://png-5.findicons.com/files/icons/977/rrze/720/globe.png]Carbon Fee and Dividend - simple, effective, and market-based.
Thanks, Bill.
How about, for PVVT, is it possible to set a unique supply flow per cooling (or heating) stage? Could the hourly value of the COOL-STAGE keyword be used in a BDL expression to dictate SUPPLY-FLOW?
Thanks,
Phil
Phil, what you're describing as an expression that reads in an hourly variable is I believe what my predecessors in doe2 history would coin as an Input Function. Not something we can do in doe 2.2+ (presently), but it comes up from time to time as something some would like to see resurface and become a feature accessible through the eQUEST interface. Further reading and examples of functions are available in your help file (doe2 reference manual) under the entry Volume 3: Topics > Building Description Language > Input Functions.
Short of rolling back and doing your project with such an Input Function in 2.1e, I don't think there is a way to accomplish this for PVVT.
VAVS and PVAVS systems have the option of using HMAX-FLOW-RATIO to define heating mode supply air ratios at a central/zonal level, but since PVAVS is distinct from PVVT in not really being able to supply heated air from the central unit based on heating/cooling mode as PVVT is designed, I don't think you want to switch system types.
And just to be sure, I checked and confirmed that HMAX-FLOW-RATIO has zero impact on PVVT systems with a dummy model.
~Nick
[cid:image001.png at 01D31C1D.898DFE90]
Nick Caton, P.E., BEMP
Senior Energy Engineer
Regional Energy Engineering Manager
Energy and Sustainability Services
Schneider Electric
D 913.564.6361
M 785.410.3317
F 913.564.6380
E nicholas.caton at schneider-electric.com
15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States
[cid:image002.png at 01D31C1D.898DFE90]
Phil,
I suggest experimenting with the AIR/TEMP-CONTROL settings available for PVVT systems. Try STAGED-VOLUME and adjust the capacity fractions to try to match the desired air flows.
If you want convenient access to the NUM-COOL-STAGES and NUM-HEAT-STAGES keywords (applicable to STAGED-VOLUME PVVT systems), modify your eQUEST installation as follows:
- Go to your eQUEST 3-64 or 3-65 Data folder
- Open the Screens folder
- Save a backup version of the BDLDialogs.txt file such as "BDLDialogs-backup.txt"
- Open your BDLDialogs.txt file with a text editor
- Search for the string, "HEAT-STAGES-DT , 3". It occurs twice.
- Insert the lines in the attached file to this email, right above the ENDCASE that follows the HEAT-STAGES-DT lines.
- Repeat the insert step for both occurrences of "HEAT-STAGES-DT , 3"
- Save the BDLDialogs.txt file
- Your Staged-Volume tab will look like this when you use STAGED-VOLUME control:
[cid:image005.png at 01D31CD4.CBDC8E30]
Regards,
~Bill
William Bishop, PE, BEMP, BEAP, CEM, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer
[cid:image006.jpg at 01D31CD4.CBDC8E30] [cid:image008.jpg at 01D31CD4.CBDC8E30]
134 South Fitzhugh Street Rochester, NY 14608
T: (585) 698-1956 F: (585) 325-6005
bbishop at pathfinder-ea.com www.pathfinder-ea.com
[http://png-5.findicons.com/files/icons/977/rrze/720/globe.png]Carbon Fee and Dividend - simple, effective, and market-based.