AHU / Retun air fan speed control 1

[remp]

If I have 1 AHU for one return air fan in a VAV system is it ok to ramp the supply air fan and return air fan up and down prportionally.? If so if I have 2 AHUs and 1 return air fan is it ok to do the same...e.g If the 2 AHUs (same size) ramp down by 50% can I ramp down the retunr air fan by 25%.??

 

[remp]

ChasBean1

Just a few things,

I agree,the Trane article is ridiculously complex, particularly on Damper Optimisation. I would not use it. If some one is smart enough out there to come up with a control sequence, good on them. It is interesting and sounds great in theory. I just put it on the website for information purposes only and I am not trying to ram it down your throat. If you dont like it please dont be so agressive in your responce.

Also Chasbean1, your paragraph on return fan speed is wrong. You said "Control return fan speed to maintain the current return air plenum pressure set point” – wow. Well, when the relief dampers open because of the building pressure sensors sensing too high a value, the relief plenum pressure drops and the return fan cranks up. When the return fan is at full speed, the building pressure drops due to higher relief airflow. This will cause the building pressure sensor to command the relief air damper more open" ....Incorrect mate! this will cause the relief air damper to close...think about it!!!


You dont seem to like air flow stations on outsdie air dampers, but you use them in your script on fan tracking on the return air fan....funny that, isnt it!!

Chasbean1, we are only trying to help each other not score points at this web site so why dont you give us all a break.

Enough said.

 

[ChasBean1]

billyg, you seemed content to walk away with the wrong solution and I was simply trying to steer you the right way. Didn't mean to get agressive.

Maybe I did have a GCE - It was a one shot post & send before looking it over. So scratch point 4, but not 1-3.

I still don't like flow stations on OA dampers unless there's a straight run. Not sure where you interpreted otherwise.

Hey, at least Lilliput liked my post! What's HVAC talk without a little passion?