Trying to compare SEER with amp draw is like trying to compare apples and oranges. It just don't compute. SEER is an average usage number based on theoretical Btu removal, amp draw, and temperature drop across a coil during a 6 minute of 10 period.

Different amp draws do not tell you anything. If you compare the amount of pumping capacity within the initial 6 minutes, then the amp draw may have some meaning.

Different amp draws tell you basic size of a compressor if all else is the same. It doesn't compare anything that has any comparative value.

For this reason, I have preached the inaccuracies of SEER rating system. Depending on the system pressure at a specific temperature would be a better rating, to tell work capability of system.

The SEER system is a rating that does not equate to real savings. When the pressure can be delayed for many minutes, the system will have a higher seer. The amp draw of a compressor is a rating that also does not have any useful meaning. Since it can change by pressure or temperature. While I love to see the lower rated compressor of Goodman, I would imagine that it is variable, depending on when the measurement is made. Goodman does have one feature that is impressive IMO. The basic system is rated without a TXV valve. When the TXV valve is used the rating goes up.

A TXV valve can be compared to fuel injection and a carburetor. It is a more accurate meter of Freon into the coil, based on the temperature of the coil and the air traveling over the coil.

Thanx for the reply, Bob.

"Different amp draws tell you basic size of a compressor if all else is the same."
- Maybe that's the issue. Manufacturers are using different sized compressor motors in same sized units.

"It doesn't compare anything that has any comparative value".
- A compressor motor that uses less amps to run costs less to operate. Yes/no?

You're trying to compare apples and oranges. Scrolls and recips pump differently - Could be the scroll pumps twice as much in the same amount of time as the recip, so if it's amp usage is less than twice that of the recip, it's still cheaper to run

Don

I went thru thru this same thought process in the mid 1990's. I was trying to understand a waterspray that I was experimenting with. The numbers just don't add up. I hold a BS in electronics, and have done many load calculations, from average power to instaneous power usage at a specific time. I am familiar with electricity and have considerable work in this field. One year, I rebuilt or replaced about 50 motors used in Dry Cleaning. I built a 3-phase generator for a customer from an old motor. I designed and built a linear generator motor for a special project I am working on.

Unless you track the amp usage vs the ambient temperature during the day, including the time the motor has been running at the calculation point, you cannot determine squat from the listed specifications. This is specific to your building also.

The SEER rating system has more twists and turns than a snake. A slight modification can change SEER by a point or more, yet the actual power usage does not change. The very high SEER systems are a crock of sh*t. The compressors are expected to run continuously all of the time. This is not good for any equipment. SEER ratings use the peak power needed, not the total power needed to keep a house cool.

I had always thought that proper sizing, installation and maintenance is far more important than amps and SEER. Keeping your coils and filters clean is the most important step to making your equipment run more efficiently and last longer. I agree with Bob too that the best thing for an air cooled condenser on a really hot day is a water mist spray.

The power consumed is the product of volts, amps, and power factor.
Without knowing the power factor (and if it is being corrected) you cannot use amps as an indication of anything.

Not sure that amp draw has any meaning in reality. My HP has a FLA of 24.5A. Never seen it draw more than 14 when running.

This is why I said you have to measure the amps rather than use the nameplate rating.

Some systems have nameplate ratings that do not have any relationship to actual amp draw, while other units are very close when measured, to the nameplate rating.

One factor, is when a compressor takes 5 minutes to reach maximum, and another unit takes only a few seconds, the unit that takes longer will draw less current, but will be ineffective longer; in a hot climate it will fail quicker than the previous example, because it will operate longer to achieve the same work.

While in school, I learned this rule as the 'law of diminishing returns' It seems to be appropiate in SEER rating tests.

Maybe the data plates state a higher amp draw to cover the manufacturers from liability in case of a circuit that is under-rated?

"This is why I said you have to measure the amps rather than use the nameplate rating."

You can measure the current till the cows come home, without the power factor you cannot compute the actual power being consumed.
P = VI cos(theta), where theta is the angle between the current and voltage waveforms, the cos(theta) term is called power factor.
Resistive loads have no phase shift and a power factor of 1.
Purely inductive loads have a 90 degrtee phase shift and a power factor of 0.
A motor has a power factor that varies with the applied load, and without adjustment (AKA correction) is usually around 0.70