AHU Oversize

[terthong]

Hi all, recently i have got my existing AHU replaced from 60RT to 80RT. From the replacement, the motor kW, chilled water supply demand, etc... have indirectly increased too. However i am having my doubt on the AHU performance, whether my supplier has oversize the 80RT AHU.

By comparing the measured pressure drop with the PD inside the catalog, how much deviation in the reading should i get to determine whether the AHU is oversize or undersize, and please enlighten me should there be other ways which i can determine whether my AHU is oversize. Btw, my AHU is being tagged onto a VSD.

Would appreciate for any kind input.

Thank You.

[Tesla]

You need to measure a lot more than static press. All measurements should be made with VSD at 100% and VAVs at 100%. Need to measure air volumes L/S, SPress b4 filt, b4 coil, b4 fan, aft fan and areas. With and without fresh air. Measure fan speed and compare with manufactures data. Then the duct measurements. It's not a small task and should involve a consultant with balancing tech taking measurements. Of course when the AHU is increased so will motor kW and CW. Is the VSD rated for increased motor? I have taken all these measurements for a consultant who passed them onto and engineer for design.