Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
ok - I think I figured something out.
In Coil:Heating:DX:MultiSpeed, there is a field "Minimum Outdoor Dry-Bulb Temperature for Compressor Operation" which I had set, but there is also a "Outdoor Dry-Bulb Temperature to Turn On Compressor" which I had left blank. The manual doesn't talk about the second one. The Energy+.idd defines the second field as:
"The outdoor temperature when the compressor is automatically turned back on following an automatic shut off because of low outdoor dry-bulb temperature. This field is only used for the calculation of HSPF. If this field is not provided, then outdoor bin temperature used in the HSPF calculation is always considered to be greater than this temperature and 'Minimum Outdoor Dry-Bulb Temperature for Compressor Operation' field described above. This assumption is based on AHRI standard 210/240 (2008) and can introduce significant error in the final value of HSPF."
I had assumed that I could leave it blank, but it gave me low HSPF. When I put a very low temperature value (for a CCASHP) it gives me better (higher) HSPF. I'm going to see if I can get similar values as a real heat pump for which I have some data curves.
I'm hoping that this can help someone with a similar problem in the future.
| | 2 | No.2 Revision |
ok - I think I figured something out.
In Coil:Heating:DX:MultiSpeed, there is a field "Minimum Outdoor Dry-Bulb Temperature for Compressor Operation" which I had set, but there is also a "Outdoor Dry-Bulb Temperature to Turn On Compressor" which I had left blank. The manual doesn't talk about the second one. The Energy+.idd defines the second field as: as:
"The
The outdoor temperature when the compressor is automatically turned back on following an automatic shut off because of low outdoor dry-bulb temperature. This field is only used for the calculation of HSPF. If this field is not provided, then outdoor bin temperature used in the HSPF calculation is always considered to be greater than this temperature and 'Minimum Outdoor Dry-Bulb Temperature for Compressor Operation' field described above. This assumption is based on AHRI standard 210/240 (2008) and can introduce significant error in the final value of HSPF."HSPF.
I had assumed that I could leave it blank, but it gave me low HSPF. When I put a very low temperature value (for a CCASHP) it gives me better (higher) HSPF. I'm going to see if I can get similar values as a real heat pump for which I have some data curves.
I'm hoping that this can help someone with a similar problem in the future.
