A/C Horsepower requirements?

Dick2 · May 27, 2015

Back in the 70's with the compressors used at that time, the normal HP drain was about 7HP.

I haven't seen the HP drain on the current generation of compressors, but have been told that it is less than what we used in the 70's. Does anyone know?

buickanddeere · May 27, 2015

What a vehicle mounted mobile air conditioner or a building air conditioner ?

Dick2 · May 27, 2015

Vehicle mounted, like the old 2-cylinder compressors that Ford and Chrysler used in the 70's.

notjustair · May 27, 2015

I had looked into adding a modern system to my old car - I believe they said it was less than 2 horsepower due to the compressor efficiency.

glennster · May 27, 2015

last a/c class we had, the hp draw on the new compressors was between 3 and 6 hp, depending on the size of compressor and vehicles interior space.

Geo-TH,In · May 27, 2015

The crazy thing, the term horsepower is over rated my some, like briggs and straton, vacuum sweepers, electric chainsaws, table saws. Very few people really know what hp is, how it's calculated, measured mechanically, converted to watts, rated in torque and radians per second, ft-lb/s.

Back in the beginning of refrigeration, a horsepower compressor was a one ton unit, it made a ton of ice in a day, or 12,000 btu's/hr. So one way to determine horsepower would be to calculate how many BTU's the A/C is putting out. Then you will only getting the theoretical, not the actual hp.

Texasmark1 · May 27, 2015

One HP is a horse raising a 33,000# weight 1 ft. in 1 minute using a frictionless pulley and rope, courtesy Mr. James Watt....aka Watts like Volts x Amps, PF = 1 for ac circuits. You have to be specific on here when you post or the boo bird(s) will come out in drove(s) and chastise you.....not naming any names......... For figuring how much work an electric motor consuming 746w./hp with a PF of unity and internally lossless has to do, Google: How much work is required to move/process one ton of heat (12k BTU/Hr.) and you will get a very informative response from the "energyvanguard.com" posting.

Jon Hagen · May 27, 2015

Depends on the compressor, remember the old 50's-60's GM A6 compressors that would drop engine idle 150 rpm and chirp the belt ?
You never heard that kind of difference with a Ford York.

I have one on a portable air compressor powered by a 3 hp B&S engine.
The Briggs just plays with that load , starting it at 150 pounds pressure, so I would guess 2-3 HP unless you are running crazy (350+) high side pressure.

Bob · May 28, 2015

I dunno... Compressor efficiency may have increased a bit, but the newer refrigerants have a higher condensing pressure for a given temp. So where's the decreased HP requirements?

JMOR · May 28, 2015

(quoted from post at 01:30:32 05/28/15) I dunno... Compressor efficiency may have increased a bit, but the newer refrigerants have a higher condensing pressure for a given temp. So where's the decreased HP requirements?

greed, Bob and further, people need to stop trying to compare automotive to home/commercial, as the auto has to operate idle to 6000 rpm & in a crappy environment by comparison, meaning that the hp required for a given BTU output will in fact be greater in the auto application. Original posters 5 -7 are well documented for that era & by most studies I have read there is little improvement today. Maybe a hand full of percentage points.

Texasmark1 · May 29, 2015

Speaking of crappy environment, the AC in my '07 65 hp Branson is rated at 14k BTU/hr. Factoring in the sun and engine/drive train
heat is obvious that it takes more capacity to do the job as compared to my house. I can cool a lot of my house with that value.

A/C Horsepower requirements?

Dick2

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buickanddeere

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Dick2

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notjustair

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glennster

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Geo-TH,In

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Texasmark1

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Jon Hagen

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Bob

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JMOR

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Texasmark1

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