×
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

Chilled water system expansion

Chilled water system expansion

Chilled water system expansion

(OP)
Does anyone out there have a rule of thumb for calculating the size of a standard expansion tank (non-bladder) for a chilled water system?  For hot water systems the rule of thumb I use is 2.0 gallons of capacity per boiler horse power for small systems and 1.5 for large systems.  I know some say you don't need expansion for chilled water systems but they're still installed.

Thanks

RE: Chilled water system expansion

I don't use rules of thumb for most things, I like to run the numbers through appropriate equations or software.
Most expansion tank catalogs will have the calculation procedure in the back.
Another option is to visit websites:
Bell and Gossett has their ESP Software that has Hydronic Specialties including sizing compression/ expansion tanks.

Wessels has downloadable software at: http://www.westank.com/index.php?page=tank

Good luck

RE: Chilled water system expansion

For a chilled water system with a closed non bladder tank if you multiply the total system volume by 2.21% you should be about right, that's good for about 100*F. Now if you go to
http://www.automatedbuildings.com/ and click on software library, go down to HVAC Engineering calculators online and click on 'Tank Volume"  it will calculate the tank size for you

RE: Chilled water system expansion

skylane,

Although the expansion of water is of a lesser magnitude in a chilled water system vs. a hot water system, you still need to accommodate fluid expansion.  If your chillers shutdown, your loop can go from chilled water temperature to ambient (or higher), with a corresponding increase in system pressure.  In any closed loop without a path for expansion, pressure rises very quickly with temperature.  Your system may have a relief valve, but it should not be your means of pressure control.

Is there a reason that you are not considering a bladder or diaphragm style tank?

---KenRad

RE: Chilled water system expansion

Take into account the glycol (if applicable) expansion rates also.

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