What should the split temps be inside and outside?


Old 10-13-12, 09:08 AM
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Join Date: Aug 2012
Posts: 28
What should the split temps be inside and outside?

I realize it may vary and the larger the split the better, but is there a ballpark figure minimum for the desired split difference for the inside and outside? Are they suppose to match almost?

Thank you.
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Old 10-14-12, 06:50 AM
hvactechfw's Avatar
Join Date: Jan 2011
Posts: 6,245
split between supply and return inside should be 15-20F
Old 10-19-12, 05:48 AM
Join Date: May 2008
Location: Wisconsin USA
Posts: 715
You size cooling equipment by the split between outdoor & indoor temps & the indoor humidity load & the summer design for your climate area.

Additionally, a room by room heat-gain calc needs to be performed to determine equipment & duct system design & sizing.

The indoor design target is normally 75-F & 50% or less relative humidity; the outdoor design temp will determine the sensible split; 90-F outdoors 75-F indoors is a 15-F sensible split, etc.

At 50% relative humidity, with tight ductwork, the indoor split at an airflow 400-CFM should normally be 19 to 21-F; higher humidity levels will result in lower indoor SA/RA temp-splits & higher condenser temp-splits compared to outdoor temps.

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