Central A/C temp diff

Aug 07, 2007 6 Replies

Does anyone know what the temp difference should be between input and output (register closest to evaporator) air for a properly sized and properly functioning residential central a/c?



Does 20F - 25F sound reasonable 10 minutes after turning the unit on in the morning after being off all night? Note: condenser is in the shade.



The above temp diff looks good to me, but I wanted to get some other opinions.


Properly sized or not the Delta T for an A/C doesn't mean all that much. There are several other readings needed to properly diagnose a system. The delta T could look good for a system but that doesn't mean it is properly sized.

It's a good differential, but it is not a conclusive performance test without confirming the proper air flow.

Without complete operating data, everything would be a WAG.

Kjpro is right, W/O more info it is a WAG! The normal range depending on airflow CFM through the E-Coil per ton of coiling, & the percent of Relative Humidity in your home it could range from say 14-F to 28-F, and yet be within that particular application condition's tolerances. - udarrell

Kjpro is right, W/O more info it is a WAG! The normal range depending on airflow CFM through the E-Coil per ton of cooling, & the percent of Relative Humidity in your home it could range from say 14-F to 28-F, and yet be within that particular application condition's tolerances. - udarrell

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