Static pressure reduction on Face and Bypass Dampers

[ParadigmEnergy]

Greetings! I'm new to this forum but whenever I use Google to find engineering answers I find this forum.

I am recommending a face and bypass damper retrofit for a large (60,000 CFM) existing fan system with the intent of saving fan energy. I'm approaching this with the fan laws in hand and have original design static pressures available. I want to install one 2 foot tall damper section in the middle of three 2 foot tall coil sections and am trying to deduce a suitable SP reduction amount. My thinking is to use a number like 1/3 as a prediction (1/3 less SP). Does this sound reasonable? Does anyone have a better approach?

Thanks!

 

[mauricestoker]

Your energy savings would be assumed to be based upon reduction in static pressure.

http://www.peci.org/ftguide/ftg/Appendices/Appendix_C_Calculations.htm#C_2_2_Equations

Attached PECI site may be waht you are looking for.

 

[tys90]

I think he's looking for the estimated reduction in SP by bypassing the coils. He said he had the fan laws and design static pressures available.

That said, I think a manufacturer's help would be the best bet here. Have them select a coil similar to what you have then select one using a F&B system. The configuration/install of their factory F&B coil is probably going to be different than your retrofit but it might give you a good starting point. From the sound of it, the retrofit is like an external face and bypass coil rather than an integral one so be sure to mention that.

 

[ParadigmEnergy]

Thanks tys90 and mauricestoker. The FTG manual is new to me and looks like a fan-tastic resource ;-)