1. Professional Member
Join Date
Sep 2004
Posts
527
Post Likes
Can someone tell me a formula for finding actual tonnage output on a chiller.

2. Professional Member
Join Date
Jun 2003
Location
in a tree looking in your window
Posts
1,428
Post Likes
This is is what I use, screwed it up the first time.

Delta T x gpm divided by 24 = tons

Tons x 24 divided by delta t = gpm

[Edited by chillrdude on 04-05-2006 at 12:16 AM]

3. Professional Member
Join Date
Feb 2006
Posts
203
Post Likes
500 x gpm x delta T

4. close but it is GPM x 500 x deltatemp divided by 12000BTU's

5. Professional Member
Join Date
Sep 2004
Posts
527
Post Likes
thanks journey man. My head was starting to hurt.Duhhh!!!!

6. how do you solve for gpm

7. Professional Member
Join Date
Sep 2004
Posts
527
Post Likes
Manufacturer should have curve chart for delta P that shows GPM.

8. Professional Member
Join Date
Sep 2002
Location
South Dakota
Posts
6,580
Post Likes

You can't solve for gpm unless you know the BTUH and you can't solve for BTUH without an accurate gpm. The most accurate way of getting gpm is using a flow meter which involves cutting pipe and installing the meter.

9. should be in ball park using pressure drop across barrel

10. Specific heat of water is essentially 1 Btu/lb-°F
There are about 8.337 lb water (60°F)/gal
8.337 * 1 = 8.337 Btu/gal-°F
There are 12,000 Btu/h or 200 Btu/min in a ton
200 Btu/min-ton / 8.337 Btu/gal-°F = 23.99 gpm-°F / ton

So multiply gpm by delta T and divide by 23.99 and you will get tons!

[Edited by Andy Schoen on 04-05-2006 at 12:04 AM]

11. Regular Guest
Join Date
Feb 2004
Posts
534
Post Likes
what if you have Glycol in system? will your formula change by adding glycol?

12. Professional Member
Join Date
Jan 2005
Posts
605
Post Likes
Yep, it'll change.

13. Originally posted by service guy
what if you have Glycol in system? will your formula change by adding glycol?
I see one source http://www.engineeringtoolbox.com/et...col-d_146.html which states specific heat of a 50/50 water ethylene glycol mix reduces specific heat to about 0.78 Btu/lb-°F (below 32°F) and has a specific gravity of 1.1. So we can figure:

8.337 * 1.1 * 0.78 = 7.153 Btu/gal-°F
There are 12,000 Btu/h or 200 Btu/min in a ton
200 Btu/min-ton / 7.153 Btu/gal-°F = 27.96 gpm-°F / ton
So in this case, multiply gpm by delta T and divide by 28 to get tons.

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•

## Related Forums

The place where Electrical professionals meet.