Is there any real difference in efficiency and cost between a single phase air conditioning unit and a three phase unit?

Thanks,

JPGREEN

Air conditioning efficiency is rated by SEER value.

From http://www.eia.doe.gov/glossary/glossary_s.htm:

Seasonal energy efficiency ratio (SEER): Ratio of the cooling output divided by the power consumption. It is the Btu of cooling output during its normal annual usage divided by the total electric energy input in watt hours during the same period. This is a measure of the cooling performance for rating central air conditioners and central heat pumps. The appliance standards required a minimum SEER of 10 for split-system central air conditioners and for split-system central heat pumps in 1992. (The average heat pump or central air conditioner sold in 1986 had an SEER of about 9.)

Three phase power is not going to offer any efficiency as compared to single phase. 3 Phase is available for usually larger units that single phase units will not be exist.

Also review:Air Conditioner Efficiency Standards: SEER 13 vs (http://www.eesi.org/publications/Fact%20Sheets/acfactsheet.htm)

Smaller units you will find both 1 & 3 phase available because both electrical systems are available. But as the tonnage gets larger, single phase units may stop being made say at 5 ton, and any unit larger will only be available in 3 phase.

A 5 ton unit 1 phase will be similar in watt load as a 5 ton 3 phase unit.

What you need to look for is the highest SEER rating you can find, in the voltage /phase you have available. If you have 3 phase available, even thou a single phase unit will work on 3 phase, always use three phase whenever possible, as this will help not stress your electrical system.