Understanding the Discrepancy in Horsepower Ratings for Air Conditioning Units

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SUMMARY

The discussion centers on the discrepancy in horsepower ratings for air conditioning units, specifically those from manufacturers like Carrier and Panasonic. A 1.5 horsepower air conditioning unit is listed with a cooling output of 13,000 KJ/h, which equates to 12,000 BTU/h or 1 ton of refrigeration. However, calculations reveal that this cooling output corresponds to approximately 4.7 horsepower, leading to confusion regarding the input and output energy ratings. It is clarified that the 1.5 horsepower rating refers to the input mechanical work, not the cooling output, and the apparent violation of energy conservation is addressed by acknowledging that other energy inputs are involved.

PREREQUISITES
  • Understanding of BTU and KJ conversions in HVAC systems
  • Familiarity with horsepower and its relation to electrical power
  • Knowledge of the Coefficient of Performance (COP) in refrigeration
  • Basic principles of energy conservation in thermodynamics
NEXT STEPS
  • Research the Coefficient of Performance (COP) and its implications in HVAC efficiency
  • Explore the relationship between horsepower, watts, and BTU in air conditioning systems
  • Investigate the energy input sources in HVAC systems beyond electrical power
  • Learn about the standards and regulations governing horsepower ratings in air conditioning units
USEFUL FOR

HVAC engineers, energy efficiency consultants, and anyone involved in the design or evaluation of air conditioning systems will benefit from this discussion.

riezer
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A manufacturer like Carrier or Panasonic listed their 1 Horsepower Aircon as having 9,500 KJ/h and 1.5 Horsepower Aircon as 13,000 KJ/h. But it doesn't tally with the BTU conversion.

1 ton refrigeration = 12000 Btu/Hour = 12,661 kJ/Hour = 3.517 kW

now 1 watt = 0.00134102209 horsepower therefore 3.517 kW = 4.7 Horsepower!

But the Carrier/Panasonic manufacturer listed 1.5 Horsepower Aircon has having 13,000 KJ/hour which is equivalent to 12000 Btu/Hour or 1 ton. Yet calculation of this data show 4.7 Horsepower. Why did Carrier/Panasonic, etc. listed them as 1.5 Horsepower Aircon?

I've been searching in net for this for hours but can't find the reason. Anyone got any idea why?
 
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1.5 hp is the input mechanical work, not the cooling output.
 
russ_watters said:
1.5 hp is the input mechanical work, not the cooling output.

You mean 3517 Watts (equivalent to 4.7 Hp) is the cooling output? Can you use watts as cooling output (the input being 1.5 hp as you mentioned)?
 
Yep. And power is power - you can use watts, horsepower, btu/hr, tons etc.
 
If the input is 1.5 HP (1200 watts) and the output is 4.7 HP (3517 watts). Doesn't it violate law of conservation of energy because the output is greater than the input?
 
No. The input electrical energy isn't the only energy input. Please read Chris's link...
 

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