Zone Equipment PTHP rated conditions warning and AHRI test conditon warning
I have created a zone equipment PTHP for the first time and applied it to a zone with default values. After running the model I received a few suspicious warnings [below]. My questions are:
- How can I resolve these warnings?
- What are E+ conditions for pthp rated heating capacity?
GetDXCoils: Coil:Heating:DX:SingleSpeed="PTHP 1 SPD DX HTG COIL" curve values * ~~~ * ... Heating Capacity Function of Temperature Curve Name = OS:CURVE:BIQUADRATIC 11 output is not equal to 1.0 (+ or - 10%) at rated conditions. Curve output at rated conditions = 0.786
Coil:Heating:DX:SingleSpeed=PTHP 1 SPD DX HTG COIL: Heating Seasonal Performance Factor calculated is not at the AHRI test condition. Review the Standard Ratings calculations in the Engineering Reference for this coil type. Check limits in Total Heating Capacity Function of Temperature Curve, Curve Type = Curve:Biquadratic, Curve Name = OS:CURVE:BIQUADRATIC 11. Check limits in EIR Function of Temperature Curve, Curve Type = Curve:Biquadratic, Curve Name = OS:CURVE:BIQUADRATIC 12
Biquadratic 11 in my model refers to the "Total Heating Capacity Function of Temperature Curve Name" field, while Biquadratic 12 refers to "Energy Input Ratio Function of Temperature Curve Name" field.
To my knowledge I had not changed the values of OS:CURVE:BIQUADRATIC 11 - they are as follows: - Coefficient1 Constant = 0.7587 - Coefficient2(x); Coefficient3(x2) = 0 - Coefficient4y = 0.027626 - Coefficient5y2 = 0.0001487 - Minimum Value of x, y = 0 - Maximum Value of x,y = 1
To my knowledge I had not changed the values of OS:CURVE:BIQUADRATIC 12 - they are as follows: - Coefficient1 Constant = 1.19248 - Coefficient2(x) = -0.03004 - Coefficient3(x2) = 0.00103745 - Coefficient4y = 0 - Coefficient5y2 = 0 - Min/Max Value of x = {-20,20} - Min/Max Value of y = {0,1}
I've scanned around pg 1785 of E+ IO Reference Manual and could not find a definition of rated conditions. I learned from IO reference the Total heating Capacity Function of Temperature curve is normalized to 1, with x and y being indoor and outdoor temperatures.
I looked at a PTAC example file with same curve type and the x and y values were greater than 1. To mimic this, I tried increasing the max/min 'y' value to a more reasonable temperature number like 20/0 degC for CURVE 11 and that has resolved the first error. I find it a bit suspicious that the default max value would be 1 if it were incorrect so I'm a bit confused.
- Did I accidentally change this, or is there some reason why the max 'y' value defaults to 1 for curve 11?
