Hi All,

I am trying to simulate an HVAC system on an hourly basis. I see that the
heat pumps, CHW Loop, HW Loop act in coherence with the outside ambient
conditions, thereby a variation is seen in the power consumption.

But I am unable to comprehend the working of FAN's alone, as they seem to
consume very high power during winters and very less power during summers.

I have modelled a supply Fan and a return Fan in the "Air-Side HVAC", with
variable speed and is operated for 24x7 across the year.

I also have an Air-Side Economizer, which starts pumping outside AIR, when
the outside Temperature falls below 65F.

Find the pdf attached, which depicts the power usage of Fan's.

January, February & December. And it drops to a low value, when it reaches
June & July.

I have also consolidated an excel that contains the Supply Air Flow,
Return Air Flow and Power consumed by the FAN's.

Find the attached excel file, which contains the above details for the
month Januray and June.

Of the 2 blocked rows, the Supply air flow volume suddenly increases from
4950.63 cfm to 12361.1cfm. But there is hardly any change in the outside
ambient conditions to have this big effect.

Also according to the results, the supply Air-flow rate is equal to the
return Air-flow rate throughout the year, but the Power consumed by Supply
Air Fan is never equal to the Return Air Fan.

Also give some inputs on how to make the Ratio of Outside Air to Total
Supply Air a constant.

Please let me know if I am missing some control variables.

Regards,
Siddharth Venkataraman