AHU Pulley Change & Motor Size

[iken]

Hi all,

I have a spreadsheet that I would like some input on (checking of my theory).

This is a simple spreadsheet for changing the pulley size to acheieve the required air flow. What I would like to know is if my cacluation of the power requirement and running amps are correct (power requirements more of concern).

Any input/suggestions would be graet.

Thanks,

 

[willard3]

I'm not going to click your link but will say this is all covered in the fan laws.

 

[iken]

I have based my spreadsheet on the fan laws. However what is being submitted upon commissioning doesn't come close to what has been calculated (running amps). The mechancial contractor has also advised a motor needs to be up sized (along with all other ancillary items) as they consider the motor will be undersized wehn a pulley change is made. Hence I need to determine (or very close to) what the actual motor kW requriements are.

All this without fan curves etc due to the age of the fan/motor etc.

The link is 100% ok.

 

[MechEngNCPE]

So you are sheaving it down about 500 rpm, why would you need to upsize the motor? You will require less brake horsepower.

 

[iken]

The spreadsheet does not show current situation. All white boxes are variables which can be (and have been) changed.

I were after a review on the spreadsheet function / calcs etc.

Thanks,