×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

air side economizer

air side economizer

air side economizer

(OP)
Anybody can help me where can I found good reference for air side economizer design and commissioning?

Thank you.

RE: air side economizer

An airside economizer is an attribute of an air handler that allows the unit to utilize "free cooling" when outside air temperature (or enthalpy) is lower than return air temperature (or enthalpy).  

When the unit activates its economizer mode, the outside air damper modulates inversely with the return air damper to provide a mixed air condition as close to the discharge air temperature setpoint as possible.  The unit is said to be in full economizer when the outside air damper is fully open, the return air damper is fully closed, the exhaust air damper fully open, the difference in supply airflow and exhaust airflow is just the air needed for pressurizing the building, and the supply air temperature setpoint is met.  This means that there is no need for the cooling coil to provide cooling - either by d/x or chilled water.  

Introducing this extra outside air brings up the need for more return air in order for the building pressure to stay at appropriate levels.  In order to bring back this increased airflow  there arises the need for an exhaust or return fan, depending on the static pressure loss of the return ductwork (if more than say 2 inches, the fan in the return position is probably the way to go.)  

I would say there are many factors in designing these systems that cannot be learned from a tutorial - it usually takes an experienced collegue or mentor to get you to the point where you understand air handler design.   

RE: air side economizer

if you are designing a specific project then the best way is to consult the HVAC unit manufucturer that you have selected.
they will give you good information about specific job for thier unit.
commssioning of the air side economizer is a part of the HVAC unit commissioning, it can be getten from manufucturer procedure.


 

RE: air side economizer

If you're not prepared to spend money on a proper maintenance then you're probably wasting your time because estimates indicate that only about one in four economizers works properly, with the remaining three provid¬ing sub-par performance or, worse yet, wasting prodigious amounts of energy. Failures are a result of maintenance deficiencies, improper con¬trol, or systemic problems. For a better understanding of what I'm talking about please read the following: http://www.energydesignresources.com/media/2919091/edr_designbrief_economizers.pdf

RE: air side economizer

Imok2,

If you aren't prepared to spend O&M money, anything the designer does is going to be crap in a few years anyway. I've seen OA dampers shut or barely cracked, with economizer disabled. Starting to think it is just cheapness.

RE: air side economizer

mauricestoker
Because I was a Refrigeration Fitter and worked in many areas of this industry doing construction and service I saw a lot of equipment that wasn't maintained properly because it was the first thing people did was cut the maintenance budget  and when they got the repair costs they beside themselves so something like econimizers require a lot of attention. Opps there I go again sorry I get carried away :>)   

RE: air side economizer

Contractor currently in the field.

90% of maintenance personell don't understand economizers and disable them when they quit functioning, or when they thing they don't want 100 degree air being pulled into the building, OR they use poor filters and the evaporator becomes filthy diminishing capacity.

Just saying I see it..almost every time.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources