hspf calculations energyplus

Hi,

I'm trying to get a house model done in E+. I need to model a heat pump (it can just be generic, but has to be something somewhat realistic). I'm using the AirLoopHVAC:UnitaryHeatPump:AirToAir:MultiSpeed object. It's for Quebec city, so region number 5 for HSPF calculation purposes.

I'm really struggling with the HSPF output. It is calculating a really low value not matter what I do. I started with the E+ database data, then I increased the rated COP of the heating coil to something impossible (like 7) and the best HSPF2 V I can get, is around 6.

I then changed the curves to data I had for a real heat pump, and I still get about the same.

I really don't know what to do. I've been trying for days to fix this but I have no idea what I'm doing wrong.

I should be able to get much higher values than 6.

Any help?

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.

Sebastien Brideau

answered 2024-01-24 10:02:31 -0500

14.1k

Aaron Boranian

updated 2024-01-25 10:34:52 -0500