Mowing How much horse power is sufficient for A/C?

[BubbaJr]

Last summer I bought a Kubota B2650 w/cab & A/C. This tractor has 3 cylinders and 26 HP, and with my 72" MMM, I can run the A/C without any disruption of power or performance of the MMM. This is based on actual usage and not on theory or conjecture.

Your mileage may Vary.

Joe

 

[marchanna]

No offense to Jeff....but I agree...I hear some statements on here that are made that people just DO NOT need to worry about.....and 1 huge one is a diesel engine loosing horsepower.

I am also having a hard time buying (although I can't back it up) that a small tractor A/C uses 4 diesel horsepower to run.

It’s surprising how much an AC compressor can draw. It all depends on how it’s sized. Even though a cab on a tractor is small, it’s got a lot of glass and acts like a greenhouse. The mechanical energy required to transfer heat out of there is completely independent of the engine size of the tractor, but rather the amount a heat that keeps transfer in from the sun, engine, and operator.

 

[MossRoad]

No offense to Jeff....but I agree...I hear some statements on here that are made that people just DO NOT need to worry about.....and 1 huge one is a diesel engine loosing horsepower.

I am also having a hard time buying (although I can't back it up) that a small tractor A/C uses 4 diesel horsepower to run.

According to this study on the effects of air conditioning and fuel economy in cars...
https://www.nrel.gov/docs/fy00osti/28960.pdf

"The power necessary to operate a vehicle air-conditioning compressor is significant - it can be greater than the engine power required to move a mid-sized vehicle at a constant speed of 56 km/h (35 mph)."

From perusing several other articles, the general consensus is the AC in a car uses about 4HP.

On another note.... what's diesel horsepower? Horsepower is horsepower is horsepower. Doesn't matter what produces it, it's the same.

 

[marchanna]

Diesel horsepower is a misnomer which people have been referring to for decades. It’s really the combination of hp, torque and gearing that is unique to diesels. Gives it the feeling of disproportionately high amount of work that can be performed with relatively low hp. But yes HP is HP - measure of consumption of energy.

 

[Old Red]

Yes, after reading this thread and responding to it I did a google search. I have found opinions on the subject but no real research on it (although I did not look hard as the general consensus was about 4hp). I was thinking I saw a mythbusters on it once but that might have been windows up and windows down....Anyway...interesting. Would love to see something published about Diesel engine and torque/horsepower being used to run an HVAC compressor. I also know that startup of an HVAC compressor uses farm more energy that running it.

I know that my old 3ton A/C running KW was close to 3KW which equates to 4 horsepower. I cannot imagine a tractor having a 3TON hvac in it....but what do I know?

 

[marchanna]

Yes, after reading this thread and responding to it I did a google search. I have found opinions on the subject but no real research on it (although I did not look hard as the general consensus was about 4hp). I was thinking I saw a mythbusters on it once but that might have been windows up and windows down....Anyway...interesting. Would love to see something published about Diesel engine and torque/horsepower being used to run an HVAC compressor. I also know that startup of an HVAC compressor uses farm more energy that running it.

I know that my old 3ton A/C running KW was close to 3KW which equates to 4 horsepower. I cannot imagine a tractor having a 3TON hvac in it....but what do I know?

That would assume that the larger the vehicle the more cooling capacity it would need. But it’s actually based on the air volume of the cab, insulation, and sources of heat. I think it’s quite possible that your truck doesn’t need as much cooling capacity as your tractor because is better insulated and has tinted windows which block out heat from the sun.

 

[zzvyb6]

You can run a play where you power a window air conditioner with a small generator. Those that have tried it with Honda 1000w inverter units say that it can run a 1000 btu A/C but the compressor won't start in ECO mode. It has to be in high rpm mode. But, it will run/cool in eco mode once the compressor comes up to speed. With more hp it will be able to cycle the compress. To me that translates to 2 hp to run but 4 to light up the compressor because the starting torque is higher. (Torque being the rate of change of power metric),

 

[marchanna]

The paper linked above, states that most auto a/c are 400-500w load. That’s only about 0.75hp.

 

[dovetail]

Thanks, everyone for a variety of answers, I'll just have to make a judgement call, might need to test drive one in August?!

 

[RaydaKub]

I would guess that if it couldn't cool the cab, they would put in a bigger unit. If they include AC, it's probably big enough to do the job. How would you tell if you were mowing that it bogged down because of the AC and not because of the heavy grass? The power is all coming from the same place. With the compressor running at a constant, you'll likely get used to the feel of things and when it bogs at all, you'll look at the grass and say "yup, it's getting thick" but never give the AC a second thought.