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08-09-2007, 11:11 AM #1
If this has been discussed before then I apologize but I could not find anything using the search feature.
I've read the discussions regarding the pro's and con's of using the temperature split (supply -vs- return temps) on freon based a/c systems. Earlier this week I inspected a fairly expensive hi-rise condo unit that used a chiller for the a/c system. The building purchased btu's from the city, ran city chilled water thru a heat exchanger for the entire building and then circulated the resulting secondary chilled water thru-out the building for each unit's individual a/c. For lack of a better method I used the temp split as an indicator of the proper performance of that system. My question is, can I use the 14° to 21° split that I normally use for a freon based split system as a guide for a chiller system? If not, then what split temp or other method should I have used to judge the performance of the system?
08-09-2007, 01:21 PM #2
Re: ChillersMy question is, can I use the 14° to 21° split that I normally use for a freon based split system as a guide for a chiller system? If not, then what split temp or other method should I have used to judge the performance of the system?
As that split you posted is simply a "rough approximation", the simple answer to your question is, "No". Temperature spilts are but only one indicator of A/C performance.
08-09-2007, 01:37 PM #3
In other words, so many other things affect the TD that TD is of little use without all the other conditions being known.
Here are two examples:
1) The coil (or filter) is blocked. The TD will be artificially high, but could be 'within range'. The system, however, needs service.
2) The coil (or filter) may be brand-spanking-new clean with a open duct in the attic (or fan speed set too high). The TD will be artificially low, but could be 'within range'. The system, however, needs service.
I quit taking TDs years ago as they meant and indicated so little that they were of no indication of the systems operation.
I believe DavidR can (hopefully will) expand on this. He has before and he knows his stuff.
08-09-2007, 03:37 PM #4
Like I said in my original post, I've read and understand all the pros/cons of temp splits or differentials. I get it....now, how would one judge the performance of a chiller based a/c like described?